PREPARED FOR:
Nestucca / Neskowin Watershed Council

PREPARED BY:
Steve Trask
Bio-Surveys,LLC.
Po Box 65
Alsea, Or.
97324

FUNDED BY:
Oregon Watershed Enhancement Board

USDA – Forest Service WY020 and WY2-005

RAPID BIO-ASSESSMENT 2004

INTRODUCTION

             A Rapid Bio-Assessment inventory was conducted for the Nestucca / Neskowin Watershed Council (NNWC) during the summer of 2004. This inventory included the Nestucca, Neskowin and Sand Lake basins and marked the final year of a three year project. The intent of the project was to gather information on the status of juvenile salmonid summer distributions and summer rearing densities. The inventory consists of extensive snorkel surveys in each basin that begin at the head of tidal influence and continue to the end of juvenile Coho distribution in each stream and its tributaries (the mainstem Nestucca began at the confluence of Beaver Cr. during 2002 and 2003 and at the confluence of Boulder Cr. during 2004).  These surveys were conducted using funds granted to the NNWC by OWEB.  The intent of these surveys is to develop base line data for each of three successive cohorts and to eventually identify long term trends in the distribution and abundance of juvenile Coho, Steelhead, Cutthroat and Chinook at the 6^th field level in response to restoration and watershed management issues.

            The escapement of adult Coho in all of the surveyed basins during the 2001, 2002, and 2003 brood years has remained insufficient to adequately seed the summer habitat currently available on a watershed scale throughout the four 5^th fields in the NNWC management area. For many of the basins and subbasins, adult escapement is the primary limiting factor for production. The trend in the adult escapement of Oregon Coast Natural (OCN) Coho since 1990 has been positive for all of the NNWC basins with the highest recorded escapement in the last 13 years occurring in 2002.     The agreement in trends between the ODFW adult SRS data and the RBA juvenile estimates for the Nestucca basin mutually support the ability of each method to assess inter annual trends. This agreement in methodology is largely a function of appropriate sampling effort for the size of the target basin. Conversely there was a radical divergence in trends within the Sand Lake / Neskowin complex when comparing these two methods. There is a weakness in the SRS sampling effort within small basins that can lead to conclusions in adult abundance and trend analysis that do not appear to be supported by the abundance of summer rearing juveniles (see table 1). This effect is discussed in more detail in the Neskowin Basin introduction.

            The 2001-2003 adult Coho estimates exhibit dramatic increases in abundance and are indicators of recent improvements in ocean conditions. ODFW’s long term SRS monitoring of adult Coho escapement suggests that the 14 year trend for the North Coast monitoring area is one of only two statistically significant trends observed in the five coastal monitoring areas. This statistically significant trend was also detected in the more intensive monitoring associated with the Oregon Plan conducted between 1997 and 2001 (E-Map). Both methods suggest that the trend is driven primarily by abundance in the Nehalem River but that a significant positive trend is also quantifiable in the Nestucca.

It is important to recognize the significant role that changes in adult escapement can have on the observed distributions and densities of juvenile salmonids.  The resultant distribution data from 2004 still does not describe all of the accessible and suitable spawning and rearing habitats for salmonids because of continued under-escapement.

 (Table 1) Adult escapement and normalized summer parr estimates for Coho

Survey                   Nestucca Basin                                    Neskowin / Sand Lake

Year        Adult escapement    Summer Parr          Adult escapement     Summer Parr

2002               3,940 (01)           189,865                          71 (01)                10,745  

2003             13,003 (02)           353,045                          16 (02)                12,700

2004               8,929 (03)           295,320                            0 (03)                12,375

             The juvenile survey method was designed to look at a sub-sample (20%) of rearing habitats using a Rapid Assay technique that could cover large distances and succeed in describing the current distribution of Coho and quantify the rearing densities of Coho and the relative abundance of Cutthroat, Steelhead, and Chinook in all of the surveyed streams and their tributaries.

            The 2004 database contains the results of 187.6 stream miles that were surveyed. This includes the full extent of Coho distribution in Sand Lake (7.1 miles), Neskowin (12.4 miles) and Nestucca basins (161.5miles), except for the segment of the mainstem Nestucca between the head of tidal influence and the bridge just below Boulder Cr., as well as the majority of West Beaver (inadequate visibility). The start point for the mainstem Nestucca survey was moved upstream 5.4 miles from Beaver Cr. in 2004 due to a funding shortfall and the observed low Coho production in this reach during 2002 and 2003. 2.8 miles of the upper Nestucca mainstem, between the Cedar Cr. bridge and the Walker Cr. confluence, were surveyed for the first time in 2004 to assess the effects on adult passage from the channel alterations which took place in the gorge just above Cedar Creek. Walker Cr. was also surveyed. If a stream is not included in the database it was not surveyed. This will occur only in situations where a mapped tributary was dry or where there was a lack of suitable visibility for the survey methodology.

METHODS

             The basins and sub-basins surveyed were selected and prioritized by ODFW, BLM, USFS and NNWC technical advisors.  Survey crews were concentrated within a basin to complete the sampling activity within a concise window of time.  This approach led to transportation efficiency and eliminated any possibility of population shifts in response to changes in flow or temperature. This strategy was altered for the mainstem Nestucca where local knowledge from the technical advisory panel of the NNWC indicated that visibility in the lower mainstem could degrade during the summer months because of temperature driven algal blooms. This resulted in a hiatus of 24 days between surveys on the mainstem Nestucca between the first 10.7 miles surveyed in June above the confluence of Beaver Cr. and the remaining 22.2 miles surveyed in July and August to the end of Coho distribution.

            Land owner contacts were made for all of the private, industrial and public ownerships that existed on both sides of every stream reach surveyed.  Developing these contacts involved extensive research in the county tax assessor’s office and then a personal contact to describe the survey and request permission for access. The land owner information was recorded (name, contact #, tax lot # and location) and will be available in subsequent years as a byproduct of this contract.

            Most surveys were initiated by randomly selecting any one of the first five pools encountered.  The protocol however was altered for small tributaries (2^nd order) where Coho presence or absence was undetermined, in these tributaries, the first pool above the confluence was selected as unit number one. This alteration in protocol was adopted to identify minor upstream temperature dependant migrations that may not have extended more than a few hundred feet. The identification of this type of migratory pattern in juvenile salmonids is critical for understanding potential limiting factors within the basin (temperature, passage, etc.). Some surveys were initiated at a point above brackish water influence or above agricultural influence where visibility conditions shifted from poor to good. In these surveys the start point of the survey will be indicated separately on the USGS quads available through the NNWC.                                                                                                                                                 

            The survey continued sampling at a 20% frequency (every fifth pool) until at least two units without Coho were observed.  In addition, pools that were perceived by the surveyor as having good rearing potential (beaver ponds, complex pools, tributary junctions) were selected as supplemental sample units to insure that the best habitat was not excluded with the random 20 percent sample. This method suggests that the data existing in the database could tend to overestimate average rearing density if these non-random units were not removed prior to a data query (the selected units are flagged as non-random in the database).

In subbasins with low rearing densities, there were situations where Coho were not detected for more than two sampled units.  These situations were left to the surveyor’s discretion, whether to continue or terminate the survey. There is a possibility that very minor, isolated populations of juvenile Coho could be overlooked in head water reaches of small 2^nd order tributaries. This tributary would have to include a strong beaver population that would impound emergent fry and truncate their normal downstream fry distribution patterns.

            Pools had to meet minimum criteria of being at least as long as the average stream width. They also had to exhibit a scour element (this factor eliminates most glide habitats) and a hydraulic control at the downstream end. There were no minimum criteria established for depth.  Only main channel pools were sampled.  Side channel pools, back waters and alcoves were not incorporated into the surveyed pool habitats. The primary reasons for not including these secondary and off channel pools is that they are typically not highly productive summer rearing locations and they compromise the consistency of measuring, summarizing and reporting lineal stream distances.

            The lineal distances represented in the database were estimated by pacing from the beginning of one sampled unit to the beginning of the next sampled unit.  The length of the sampled pool is an independent quantity, which was always measured and not estimated.  A minimum of three lineal estimates were also measured with a hip chain for each surveyed stream to develop a calibration factor for each surveyors estimate of distance.  Total distances represented in the database are consistently greater than map wheeled distances using USGS 1:24,000 series maps. This is related to the level of sinuosity within the floodplain that is not incorporated in mapping. If you are attempting to overlay this database on existing stream layer information there would be a need to justify lineal distances with known tributary junctions (these can be found in the comments column). In addition, the USFS under contract to the NNWC will be producing a digitized stream layer of Coho distribution for incorporation into the current GIS database.

Pool widths were generally estimated.  Because pool widths vary significantly within a single unit, a visual estimate of the average width was considered adequate.  Pool widths were typically measured at intervals throughout the survey to calibrate the surveyor’s ability to judge distance.

            The snorkeler entered the pool from the downstream end and proceeded to the transition from pool to riffle at the head of the pool.  In pools with large numbers of juveniles of different species, multiple passes were completed to enumerate by species. (Coho first pass, 0+ trout second pass, etc. ). This allowed the surveyor to concentrate on a single species and is important to the collection of an accurate value. In addition, older age class Steelhead and Cutthroat were often easier to enumerate on the second pass because they were concentrating on locating food items stirred up during the surveyors first pass and appeared to have less of their initial avoidance behavior.

            In large order stream corridors (mainstem Nestucca), two snorkelers surveyed parallel to each other, splitting the difference to the center from each bank.

            A cover/complexity rating was attributed to each pool sampled. This rating was an attempt to qualify the habitat sampled within the reach. The 1 - 5 rating is based on the abundance of multiple cover components within a sampled unit (wood, large substrate, undercut bank, overhanging vegetation). Excessive depth (>3 ft) was not considered a significant cover component. The following criteria were utilized:

1          0 cover present

2          1-25   %   of the pool surface area is associated with cover

3          26-50 %   of the pool surface area is associated with cover

4          51-75 %   of the pool surface area is associated with cover

5          > 75   %   of the pool surface area is associated with cover

            A point to consider here is that the frequency of higher complexity pools increases with a decrease in stream order. This inverse relationship is primarily a function of average channel width and the resultant ability of narrow channels to retain higher densities of migratory wood. Channel morphology begins to play a much more significant role in this relationship during winter flow regimes where increases in floodplain interaction and the abundance of low velocity habitat may become as significant as wood complexity.

 A numerical rating was given to each sampled unit for the surveyor’s estimate of visibility. The following criteria were utilized:

Visibility                                                                

1          excellent                                                    

2          moderate                                                   

3          poor                                                           

             This variable delivers a measure of confidence to the collected data. Survey segments with a measure of 1 can assume normal probabilities of detection (the observed is within 20 percent of the actual for Coho). Segments with a measure of 2 suggest that less confidence can be applied to the observed number (uncalibrated) and segments with a visibility rating of 3 suggest that the observation can probably be used for only an assessment of presence or absence.

            There was also commentary recorded within each of the surveyed reaches that included information on temperature, tributary junctions, culvert function, the abundance of other species and adjacent land use. This commentary is included in only the raw Access database under the “comments” field and not in the Excel cd.

            The database contains fields designed to facilitate the development of a GIS data layer. These are LLID location numbers that are unique for each stream segment and latitude and longitude coordinates collected for unique features. Lat / Long coordinates are reported in degrees, minutes and seconds. Latitude and longitude values were not collected for start points because these values already exist in the actual LLID number used to initiate a surveyed reach.

GENERAL OBSERVATIONS

  The distribution and abundance of Coho juveniles observed during the 2004 summer field season in the Nestucca and Neskowin basins was the result of a wide spread decrease in adult escapement during the 2003 brood year. This resulted in general reductions in juvenile abundance when compared to the strong response observed the previous year from the 2002 Coho cohort.

The summation of data from three years of inventory in these watersheds illustrates the relative production significance and spawning location preferences between each of three separate cohorts, or generations, of Coho returning to each basin. The pattern that emerges for the Nestucca clearly shows the 2001 adult brood as the smallest, the 2002 adult brood as nearly twice as large, and the 2003 adult brood in the middle nearer to the size of the larger (table 1). The changes in adult estimates for these years in the Nestucca basin appear to closely match the changes in summer rearing estimates which lends validity to this comparison.

The pattern observed for Coho in the Neskowin / Sand Lake complex is not as clear. The trends observed in adult estimates disagree with the trends observed in juvenile estimates. Adult estimates have been steadily decreasing for these two basins while combined summer parr abundance over three years has increased by 15%. Juvenile abundance patterns in the Neskowin basin appear to follow those from the Nestucca more closely than those from Sand Lake.

Juvenile abundance estimates from Sand Lake appear to stand alone, exhibiting a trend in abundance unique from either the Nestucca or Neskowin basins. The 2002 adult brood appeared to represent the smallest cohort in Sand Lake, based on 2003 summer parr estimates. The 2001 adult brood was approximately 41% larger, and the 2003 adult brood was the largest of the three cohorts, about 72% larger than the 2001 brood. The unique patterns encountered in the Sand Lake basin are in part a function of their depressed and erratic states of production but also may be a function of the specialized adaptations for survival and rearing that the specific Sand Lake habitats dictate through natural selection. More discussion of these factors is included in each basin’s respective introduction.    

The above patterns only compare differences (strengths and weaknesses) between the three separate Coho cohorts. In order to follow how each cohort fairs individually at over winter survival, ocean survival, and spawning success another three consecutive years of monitoring would be necessary (i.e. the fourth year of data would reflect the life cycle success of the first year, its “cohort”). A weak or strong cohort may be uniquely affected by a number of factors including yearly differences in ocean conditions, stream flow patterns, catch limits, and hatchery straying.

Most habitats are still not seeded to capacity in the inventoried systems and there remains extensive summer habitat available to salmonids that is currently under-utilized. There were some exceptions - Baxter, Bear, East Beaver, Elk, Louie, Sourgrass, and Trib F / Nestucca (2004) exhibited a fully seeded condition for Coho during both the 2002 and 2003 inventories (Trib F for 2004 also). These tributaries represent important anchor habitats for OCN Coho. For the following review, we are considering 1.5 fish / sq.meter a fully seeded density for Coho. There are concerns from many biologists that this estimate of fully seeded does not represent the production potential that exists in completely functional Coho habitat that is benefiting from the nutrient loading of adult spawning salmonids (eggs, carcasses). There are excellent examples from 2003 in Elk Cr., Baxter Cr., and East Beaver Cr. of stream reaches that far exceeded the level of 1.5 fish/sq.m. of pool surface area (up to 3.0 fish/sq.m. in Baxter and Elk). The intent of establishing this target of full seeding is to provide a platform for comparing stream reaches to each other and to themselves over time. The graphics available in the Nestucca / Neskowin cd utilize this value to normalize scaling.

            The average density for a surveyed reach is an excellent measure of trend that can be monitored from year to year. However, it tends to portray only a general description of the current status within a reach. Understanding how each reach is functioning is more accurately interpreted in a review of how the rearing density changes within the reach. The graphics provided in electronic format with this summary are essential for the proper interpretation of this review (refer to 2004 Nestucca / Neskowin cd, NNWC).

 Distribution profiles 

            The distribution of juveniles and their observed rearing densities for each surveyed reach provide a basis for understanding how each reach is functioning in relation to the remainder of the basin or subbasin. These profiles can help identify spawning locations, identify potential barriers to upstream adult and juvenile migration, identify the end point of Coho distribution and they may also indicate how juvenile salmonid populations are responding to environmental variables such as increased temperature. You will find a review of these distribution profiles within this document for each of the major basins and subbasins surveyed during the 2004 field season.

Location of spawning destinations

 The approximate locations of spawning pairs was observable in many of the sampled sub basins by the presence of a distinct spike in rearing density that trailed off rapidly just upstream. The physical location of a spawning destination has a range of variance plus or minus 4 pools due to the 20 percent sample methodology.  Depending on the average distance between pools, this typically describes a maximum lineal distance that varies between 150 ft. in a small 2nd order tributary to 800 ft. in a fourth order tributary. To utilize the database to identify spawning destinations, an additional precaution is necessary. Surveyed lineal distances are typically longer than calculated distances (map wheel, GIS, etc.) due to the sinuosity of the active channel that is not displayed in the 1:24,000 series USGS maps. To accurately evaluate site specific locations it is important to utilize the digitized map layer that has been justified to known end points and tributary junctions. This layer was developed by the USFS in 2002 and 2003 and is available from the Nestucca / Neskowin Watersheds Council.

            The average densities generated represent a snapshot in time of the current condition that can be compared to known levels of abundance that exist in fully seeded and fully functional Coho habitats. These densities also provide a method for quantifying changes in rearing densities by reach or subbasin over time. Average densities utilized as a metric in this analysis are calculated for pool surface areas only. Lower levels of Coho abundance exist in fast water (riffle/rapid) and glide habitats. Replicate surveys conducted in these same reaches in subsequent years will function as an indicator of response to future restoration and enhancement strategies and potential changes in land use. It does not however, provide any indication of actual smolt production because of the distinct relationship between juvenile Coho survival and the abundance of high quality winter habitat.

Adult and Juvenile Barriers

                Adult migration barriers are verified by determining that no juvenile production is occurring above a given obstruction (culvert, falls, debris jam, beaver dam, etc.). There are many barriers, both natural and manmade that impact the migration of salmonids in coastal basins. Some are definitive barriers that are obvious obstructions (such as the bedrock falls on the Little Nestucca below the confluence of Fall Cr., which is a migration barrier to juveniles?) Many barriers however, only impede adult salmonid migrations during low flow regimes. Summer juvenile inventories allow us to definitively quantify whether passage was obtained at any point during the season of adult migration.

            Juvenile salmonids typically migrate upstream for a variety of reasons (temperature, winter hydraulic refuge, food resources). Hydraulic refuge and food resources are typically fall, winter and spring migrations that would not be detectable during summer population inventories. Temperature however, is probably the most significant driver of upstream juvenile salmonid migrations during summer flow regimes. Juvenile barriers are subjective to the eye of the observer. The trend in juvenile density can be a method of detecting either partial or full barriers to upstream migration. Each of the surveyed reaches contains a comments section in the Access database to note the presence of culverts, jams and other physical factors that may influence the ability of salmonid populations to make full use of aquatic corridors.  

Temperature Dependant Migrations

Potential temperature dependant migrations can be observed in the database by looking for densities that decrease significantly as the lineal distance increases from the mouth of the stream or tributary. This is more likely to be observed in the case of low abundance years where tributary habitats that are seeded to capacity are the exception. During years of high abundance there is a more significant potential for density dependant upstream migrations that would be indistinguishable from the distribution pattern mentioned above. The recognition of this migration pattern allows us, during years of low escapement, to identify important sources of high water quality within the basin that may be traditionally overlooked because of some other morphological condition that suggests to us that there is no significant potential for rearing salmonids (i.e. lack of spawning gravel). These stream reaches typically exhibit declining densities with increased distance from the mouth and no indication of a spawning peak (a point near the upper distribution of the population with significantly higher rearing densities). These tributaries may be functioning as important summer refugia for salmonid juveniles threatened by increasing temperatures in the mainstems.

 Precautions

             The specific location of spawning sites does not infer that the highest quality spawning gravels were targeted by adult salmonids or that there is any relationship between the location of a redd and the quality of the rearing habitat that exists adjacent to these locations.

            The location and distribution of juvenile Coho represented in the database is not related to the quality of the rearing habitat that exists in the aquatic corridor adjacent to these sites.

            The average densities that can be generated as an end product for each stream reach are the result of a 20 percent sample. Consequently, they probably vary significantly around the true average density. There are many sources of potential variation, start point, number of units sampled within the reach, surveyor variability, etc. The range of variability for at least one of these variables (start point), was documented in the final review of the 1998 Rapid Bio-Assessment conducted by Bio-Surveys for the Midcoast Watershed Council. To facilitate the proper utilization of the data included in this inventory, the 1998 results are included in Table 2. The true average density of a stream reach was retrieved by querying the database from an ODFW survey on East Fk. Lobster where every pool was sampled. Comparisons could then be made between the true average density and a randomly selected 20 percent sub sample (every 5th pool). Only mainstem pools were utilized within the range of Coho distribution to match the protocol for the Rapid Bio-Assessment. Table 2 contains this comparison, exhibiting the variation in average density based on the selection of different starting points.

(Table 2)

SAMPLE FREQUENCY     AVG. COHO DENSITY               AVG. SH DENSITY    AVG. CUT DENSITY    AVG. 0+ DENSITY

100 %                               1.07                                .03                                  .04                    .13                   50  %                               1.10                                .04                                  .03                     .14

20 % Start Pool 1               0.87                               .04                                  .03                     .13

20 % Start Pool 3              1.01                                .03                                  .03                     .13

20 % Start Pool 5              1.13                                .05                                  .04                     .12

                When calculating the average density of juvenile Coho in a particular stream reach, it is important that only the data be utilized that falls within the distribution of Coho. Many stream reaches contain sample sites that extend well above the actual distribution of juvenile Coho. Including these data points significantly underestimates the average rearing density and provides a poor foundation for monitoring trends in subsequent years. There are also many streams surveyed that have a downstream point of Coho distribution that is well above the start of the survey reach. Two factors for each stream reach surveyed are key elements for trend analysis, the extent of the distribution and the average density within that distribution.

SITE SPECIFIC OBSERVATIONS

 Site specific observations within this document have been organized in a format that utilizes GIS definitions to describe basins and subbasins. The area within the NNWC management zone includes four 5^th fields. Each of these 5^th fields has been summarized separately. The expanded juvenile salmonid estimates are also broken down into 5^th field estimates (i.e., the mainstem Nestucca does not include the production from the Little Nestucca).

Nestucca

The Nestucca mainstem survey began at the confluence of Beaver Cr. in 2002 and 2003. Habitat downstream of this point exhibited poor visibility resulting from suspended solids and algae. This mainstem start point was moved upstream 5.4 miles to Boulder Cr. in 2004 due to reduced funding and previous observations of low mainstem Coho production between these two tributaries. There is significant juvenile salmonid rearing that occurs in the 14.5 river miles between Pacific City and the confluence of Beaver Cr. (6.6 of these river miles are classified as intertidal, from the boat ramp in Pacific City to the head of tide at the Cloverdale bridge). This potential production has not been accounted for in the 4^th or 5^th field production estimates below.

The following tables represent the contribution in salmonid production (by species) from each tributary to the Nestucca 4^th field Watershed.  Table 4 represents total results from 2004 inventories and Table 3 represents production within just the Main Nestucca 5^th field (minus the Little Nestucca subbasin). These production estimates are based on an expansion of the 20% snorkel sample in pools only and therefore do not constitute an entire production estimate for the basin. In addition, production from several streams that were not surveyed during all three years has been omitted from the tables in an effort to normalize the comparisons. These estimates greatly under estimate the standing crop of 0+, Steelhead and Cutthroat because a large component of the basin’s standing crop is summer rearing in riffle / rapid and glide habitats that were not inventoried. In addition, there is also production for these three groups that extends upstream beyond the end point of Coho distribution where the surveys were terminated. This table however, can be utilized to establish a baseline for trend monitoring for subsequent survey years on the basin wide scale and by tributary. The table functions well to establish relative production potentials that can be utilized as a foundation for prioritizing restoration opportunities.

Basin wide Coho production rose 92% in 2003 in response to a surge in adult escapement. That year stands as the largest summer rearing population within our three year inventory, nearly twice as large as the 2002 population and 20% larger than the 2004 population. Highest rearing increases in 2003 were found in Powder Cr. (798%), Moon Cr. (533%), Little Nestucca Mainstem (327%), Niagara Cr. (265%), Mainstem Nestucca (91%), Three Rivers (70%), Elk Cr. (58%), and Bear Cr./Nestucca (40%). Habitat reaches seeded to capacity that year were found in Elk Cr., Bear Cr./Nestucca, and East Beaver Cr.

In response to a 31% drop in adult escapement estimates 2004 summer rearing estimates fell 16.4%. The top five subbasins have changed little from year to year except for the continuous rise of Niagara Cr. to the #1 producing tributary. The Nestucca mainstem has remained the largest component of basin wide Coho production during all years. Moon Cr. rose to the second largest tributary producer in 2004 leaving Beaver Cr. in third, Bear Cr. in fourth, and Elk Cr. in fifth. Highest average rearing densities for Coho were observed again in Trib F/Nestucca/2004 (1.5fish/sq.m.), Niagara (1.1 fish/sq.m.), Elk (1.0 fish/sq.m.), and Bear/Nestucca (0.94 fish/sq.m.). These density levels all display decreases from 2003 figures. Trib F of the Nestucca appeared to represent the only habitat within the basin that was seeded to capacity in 2004. Table 3 clearly illustrates the changes in abundance between these subbasins from year to year.

(Table 3) Coho production trends in the Nestucca 5^th field.

-Mainstem figures and % totals in Table 3 above have been normalized to include identical habitats

 Decreases in Coho production were noted throughout most reaches in 2004 with most notable losses recorded in the Nestucca mainstem (down 11.5%), the Little Nestucca mainstem (down 54%), Beaver (down 49%), Elk (down 51.4%), and Wolfe (down 61%). Exceptions to this trend included Bear Cr. of the Nestucca (up 14%), Niagara (up 16.4%), and Powder (up 42%). These three streams alone displayed continued production growth for two consecutive years. Notably, almost every tributary to the Little Nestucca showed an increase in 2004 despite basin wide reductions led by a dramatic reduction in mainstem rearing. Also worth noting were the greatly depressed populations seen this year in Elk Cr. and Beaver Cr., two primary producers of Coho and the only two subbasins to display a smaller summer rearing population in 2004 than in 2002 (the lowest year of the three year inventory for Coho abundance). These comparisons are drawn from a total of 161.5 miles of Coho distribution within the Nestucca basin.          

These shifts in populations may be influenced by a number of factors ranging from differences in habitat accessibility based on winter stream flow regimes, to behavioral mechanisms that dictate which tributary will receive the bulk of the adult escapement. For example, 2004 summer rearing patterns (a year of moderate abundance compared to 2003) appeared to reflect more spawning focus in tributary reaches as compared to 2003’s higher mainstem Nestucca, Little Nestucca, and Beaver Cr. focus. Tributary distributions in general were also greater for most reaches in 2004 while rearing densities decreased. The most important trend to emerge for Coho out of all three years is the continued spawning focus on the upper basin tributaries, including Elk Cr., Bear Cr., Niagara Cr., Moon Cr., East Beaver Cr., Louie Cr., Sourgrass Cr., and the South Fork Little Nestucca, in addition to the extremely high rearing densities observed in the upper reaches of the Nestucca mainstem.  

Overall 1+Steelhead rearing within surveyed reaches has dropped two years in a row by 11%. This emerges as a conspicuous negative trend that may reflect something as serious as a substantial loss of wild smolt production. 0+trout abundance displayed a 44% decline basin wide in 2003 then rose by 37% in 2004. The final basin-wide population size of 95,955 (normalized) in 2004 remained substantially lower than the 2002 population of 130,405 (normalized). This trend supports the observation that a decrease in production is occurring.

Increases in 1+Steelhead rearing were observed in Bear Cr./Nestucca (53%) and the Little Nestucca subbasin (26%) in 2003, while the largest reductions in abundance were recorded in Moon Cr. (-44%), Mainstem Nestucca (-26%), and East Beaver Cr. (-18%). 2004 surveys observed more widespread losses to this population in the Mainstem Nestucca (-27%), the Little Nestucca subbasin (-42%), Three Rivers (-42%), Beaver Cr. (-13%), and Bear Cr./Nestucca (-21%). Notable increases were observed this year in Bays Cr. (+235%, artificially supported by a large release of hatchery smolts within the tributary), Moon Cr. (+42%), Horn Cr. (+63%), and Bear Cr./Little Nestucca (+185%). The top five Steelhead producers remained similar during all three inventoried years – the Nestucca mainstem, Beaver Cr., Three Rivers, Moon Cr., and the Little Nestucca mainstem. A large 62% reduction in 1+Steelhead abundance in the Little Nestucca mainstem in 2004 coupled with the artificial surge in the Bays Cr. population from hatchery releases has switched the 5^th place ranking between these two reaches

(Table 4) 2004 Basin Wide Inventory (Includes Nestucca, Little Nestucca and Nestucca Bay 5^th fields)

* Highlighted estimates represent the top 5 producers by species and age class for 2004

(1) % contributions are indicated for only those subbasins that contributed greater than 1% of the total.

(2) The Beaver Cr. estimates do not include the additional production available in West Beaver because of the lack of visibility for conducting the snorkel inventory.

(3) Data not normalized to 2002 and 2003 inventories

(Table 5)

Expanded Nestucca (5^th field) Estimates of Juvenile Salmonid Production

Survey Year            Coho                 0+             Sthd                Cut

2002                      159,420         122,895        22,680            19,570

2003                      291,265           61,360        19,795            15,150

2004                      245,215           86,690        18,280            17,030

Table 5 above deletes the production occurring in the Little Nestucca and facilitates a comparison within a  single 5^th field. 

Table 5 and individual stream comparison tables below also delete production occurring in the Nestucca mainstem below the Boulder Cr. Bridge (2002, 2003) and above the Cedar Cr. bridge (2004), in Alder Cr. (2003, 2004), in Bower Cr. (2002, 2003), in George Cr. (2002, 2003), in Sailing Cr. (2002, 2003), in Sanders Cr. (2002, 2003), in Turpy Cr. (2003), in Town Lake (2002, 2003), and in Walker Cr. (2004) since survey efforts in these habitats were not consistent for all three years. 

Mainstem Nestucca

(Table 6)

Expanded Mainstem Nestucca  Estimates of Juvenile Salmonid Production and Percent Contribution to the 5^th field

Survey Year              Coho                      0+                       Sthd                        Cut

2002                     82,385 (52%)      33,275 (27%)        6,780 (30%)*        4,630 (24%)*

2003                   148,800 (51%)      17,280 (28%)        5,140 (26%)*        3,275 (22%)*

2004                   131,715 (54%)      28,730 (33%)        3,750 (21%)*        2,370 (14%)*

The 5^th field percent contributions would be significantly higher if the rearing occurring in the

lower 14 miles of mainstem were included.

Data from the Mainstem has been normalized in Tables 5 and 6 to represent only habitat between the Boulder Cr. and

Cedar Cr. bridges.

            The Nestucca mainstem, from the bridge just below Boulder Cr. to the end of Coho distribution just below confluence of Walker Cr., was again the single most productive component of the entire 5^th field for all species of juvenile salmonids. 2004 Coho abundance in this reach fell slightly 11.5% after the radical 91% rise observed in 2003. This loss closely matches the basin-wide 15.8% drop in Coho abundance. Combining the three years of data, however, still indicates an overall positive growth trend in the Coho population here. This mainstem population was 164% larger than the production from the entire Little Nestucca basin and estimates from just this reach alone accounted for more than half of the total Nestucca 5^th field production. This segment of mainstem rearing habitat encompassed approximately 33.1 lineal miles and exhibited by far the greatest production potential in the basin. 5.4 miles of low production habitat between Beaver Cr. and Boulder Cr. were truncated in 2004 due to a lack of funds while 2.8 miles of flat meadow habitat between Cedar Cr. and Walker Cr. were added to the upper endpoint. This reach was opened to anadromous migration during the summer of 2003 by blasting within the narrow boulder gorge just above the Cedar Cr. bridge. It is estimated that dropping the lower 5.4 miles of mainstem from the inventory reduced the mainstem Coho production estimate by approximately 5 percent based on historical abundances observed in this reach. 1+Steelhead and Cutthroat totals may have been reduced by as much as 20% and juvenile Chinook totals by as much as 30%. Data used in the above tables and in the discussion below have been normalized between years to facilitate an accurate comparison of trends.

            Many of the smaller order tributaries that contribute flow to the mainstem truncate fish distribution with definitive anadromous barriers, steep gradients or elevated summer temperatures. The maintenance of the water quality (summer flows, temperature, DO) in the mainstem is therefore paramount to preserving and optimizing the production potential of the system as a whole because of the vast abundance of habitat it provides. Because diminishing water quality has been identified in the NNWC Watershed Assessment of 1998 as a primary issue in the management and restoration of the basin, it is important to understand that for salmonids to flourish on a scale that mimics historical conditions, the final goal is to attain quantifiable improvements in mainstem water quality parameters (see recommendations).

            The distribution of summer rearing Coho juveniles during the last three years of inventories has remained nearly identical. Most production appears to be concentrated above the confluence of Boulder Cr. and below the confluence of Elk Cr.  High counts continue for an additional two miles above Elk Cr. where a final spike in abundance was observed. Peak Coho numbers occur in the vicinity of the Niagara Cr. confluence and in the zone just upstream from the Elk Cr. confluence. This year’s results display a productive corridor of approximately 32.7 miles in length from Boulder Cr. to the end of distribution just below Walker Creek. Some of the mainstem pools in this reach were summer rearing up to 1,800 Coho juveniles each. The average Coho rearing density for all mainstem pool habitats dropped slightly from 0.52 fish/sq.m. in 2003 to 0.4 fish/sq.m. in 2004, with a peak density of 2.14 fish/sq.m. occurring just below Cedar Creek. The six mile zone below Cedar Cr. was the only reach where individual pools displayed Coho rearing densities at or above a level of full seeding at 1.5 fish/sq.m. Average rearing density across this zone, however, remained below this level at 0.7 fish/sq.m. Coho throughout the mainstem were relying heavily on the shallow cobble margins in the absence of complex wood. In habitats with some level of wood roughness densities were double the adjacent pools with none. Indications are that wood complexity is a very important component of even summer habitats in these large stream corridors for providing protection from predation. The high level of juvenile densities above the confluence of Elk Cr. indicates that the mainstem spawning of adult Coho in this reach is significant. The restoration projects observed in this reach, including sill-logs used to create dam pools and plunge pools, appear to have been very successful and well placed in areas of ideal gravel size, significant juvenile abundance and extensive floodplain interaction.

            The 2.8 miles of habitat appended to the inventory between Cedar Cr. and Walker Cr. revealed minor colonization of this new habitat. The presence of a small population of juvenile Coho in the middle of this meadow indicated that the successful spawning of at least one pair of adult Coho occurred in 2003. Adult passage through the boulder gorge still appears difficult under moderate winter flow conditions. An expanded estimate of 115 juvenile Coho was observed above the gorge in a low rearing density of 0.01 fish/sq.m. Habitat in this reach was characterized by long slow grassy pools with a silt covered bottom and a low abundance of gravel or in-stream wood. Distribution ended below the main highway bridge and gauging station just downstream of the Walker Cr. confluence. Habitat conditions began to change about 0.8 miles below this bridge with an increase in clean gravel and larger angular rock on the stream bottom along with the beginnings of a solid alder canopy and small in-channel wood jams. An expanded estimate of 15 1+Steelhead was also reported in this reach.

            1+Steelhead distribution during all three years remains distinctly different than Coho distribution with peak numbers occurring lower in the surveyed section and dropping off rapidly above survey mile 21 (just below Elk Cr.). This contrast in distribution is identical to the patterns observed in Cutthroat and Chinook juveniles during all three years. Because of the increasing size of the pool surface areas progressing downstream from the headwaters the lower densities of Steelhead observed actually represent higher production. In 2004 there were no pools above the 21 mile mark (from the bridge below Boulder Cr.) with more than 10 Steelhead observed. In comparison, some pools just above the confluence of Boulder Cr. were rearing between 30 and 40 older age class Steelhead. This year’s inventory exhibited a continued decline in abundance throughout the mainstem reaches. A loss of 27% of 1+Steelhead was observed in 2004, closely matching last year’s 24% decline. Proportionately more 1+Steelhead were noted upstream of Niagara Cr., however, during 2004 and moderate counts extended approximately 10 miles further upstream (to RM 21) compared to 2003. This 1+Steelhead distribution closely resembles the pattern observed in 2002 when the total population size was almost twice that of 2004. A similar 28% decline was noted in Cutthroat trout abundance in the mainstem during the 2004 survey. The 48% drop in 0+trout abundance observed in 2003 stands out as the most dramatic change among these species and a similar decline in 1+trout abundance had been predicted for 2004. The 0+trout population in 2004 appears to be on the rebound with an observed growth of 66%, almost up to the level seen in 2002. The obvious long term concern is for the continued declining trend in the abundance of adult steelhead.

Indications are that large numbers of Steelhead may be summer rearing in the mainstem well below the confluence of Boulder Cr. with a steady decline in the number/pool as the distance increases upstream. This same pattern can be seen in the last two years of surveys in an amplified version which includes downstream habitats extending to the Beaver Cr. confluence. The methodology employed during these snorkel inventories only portrays a picture of pool habitats and even larger numbers of Steelhead juveniles were present in each riffle and rapid habitat type. The significant observation here is the increasing importance of the mainstem for summer Steelhead rearing in a lineal progression downstream from the headwaters. Because none of the surveys included the mainstem below the confluence of Beaver Cr. it was not possible to assess whether this trend of increasing abundance would have continued.

            Cutthroat distribution very nearly mimicked the pattern observed for Steelhead with a steady decrease in abundance observed with the lineal progression above the confluence of Boulder Cr. Cutthroat populations declined 29% throughout the mainstem survey reach in 2003 and another 28% in 2004. A significant loss such as this repeated over two years is an alarming trend and in conjunction with the notable declines observed in Steelhead abundance deserves additional monitoring. The distribution of older age class Cutthroats may be closely linked with the seasonal distribution of Chinook fry in their steady progression towards the estuary. The close resemblance between 2002, 2003, and 2004 1+trout and juvenile Chinook distribution patterns continues to support this hypothesis. 

There was an expanded estimate of 43,040 juvenile Chinook observed in the 2003 inventory above the confluence of Beaver Cr., a 34% decrease in abundance from 2002.  Only 29,565 of these were rearing above Boulder Cr. Their distribution closely matched the same pattern seen in Steelhead and Cutthroat with decreasing abundance above the confluence of Beaver Creek. 2004 surveys found an expanded estimate of 45,620 juvenile Chinook above the Boulder Cr. bridge. This accounts for more than the entire surveyed mainstem population of 2003 and stands as a 54% gain in a normalized comparison (only counting upstream from Boulder Cr. for both years). This level of summer rearing remains 14% below the 2002 juvenile Chinook population in a normalized comparison. Most juvenile Chinook were observed below the confluence of Niagara Cr. during all three years with distribution continuing up to RM 27.5 (from Boulder Cr.) in 2004. The Elk Cr. confluence, for reference, was at RM 21 of the 2004 survey. This represents an increase of 6.5 miles from the 2003 Chinook distribution and remains 3 miles further than the 2002 distribution. The changes in juvenile Chinook abundance may be insignificant because of their life history pattern that programs them to steadily migrate toward the estuary after emergence. This migration may vary from year to year based on the timing of spawning events, spring rains and mainstem temperatures. A mainstem survey 2 weeks later would likely observe a decline in abundance. Adult Spring Chinook, Summer Steelhead, and Chum Salmon were also observed within the mainstem inventory.

Alder Cr.

            Alder Cr. was a minor producer of Coho during both 2003 and 2004 surveys. Summer parr abundance increased by 11% between these two years and average rearing density increased from 0.4 fish/sq.m. to 0.6 fish/sq.m. Peaks in rearing density reached just over 1.0 fish/sq.m. during each year. A significant Coho distribution of 2.3 miles was observed each year despite the low abundances. All of the Coho in Alder Cr. appear to be the result of in-stream spawning. Alder Cr. presents abundant habitat for temperature refugia from the Nestucca mainstem though little evidence of this type of migration was seen. High flows, low temperatures, and easy juvenile passage were observed throughout the survey length. Most of Alder Cr. is dominated by larger rock and boulder substrates.

Bays Cr.

            Coho numbers fell 38 % in Bays Cr. this year after a dramatic increase of 573% in 2003. A strong positive trend for Coho in the subbasin remains apparent. Summer rearing density averaged 0.23 fish/sq.m., falling from 0.7 fish/sq.m. in 2003. A peak density of 1.0 fish/sq.m. was observed at RM 1.3, approximately 0.4 miles downstream from the 2003 peak. Distribution increased in the subbasin for the second consecutive year. An additional 0.7 miles was gained to reach 3.2 miles total.

            Much of the reduction to the 2004 Bays Cr. Coho production may be related to the surge in 1+Steelhead abundance noted this year and the resulting density dependant migration pressure applied to Coho by the added competition. The 1+Steelhead population in the subbasin was up 235% in 2004 from the previous year from the tributary release of hatchery smolts that appeared to have residualized. In addition, Cutthroat abundance was up 177% from the 2003 inventories. Extremely high 1+Steelhead counts were encountered in the first mile of survey, out-numbering the abundance of Coho in the same pool. The total 2004 population sizes for these two species in Bays Cr. were nearly the same. Most Cutthroat were observed in this same zone. There were no Chinook observed in the 2004 survey and neither Coho abundance or rearing density were noted as unusually high.

Bear Cr.

            Bear Cr. exhibited a continued rise in its summer rearing estimate for Coho despite observed reductions in the majority of the Nestucca basin. This subbasin was one of only 3 (including Niagara and Powder) to experience increases in Coho production for both 2003 and 2004. An increase of 14% in 2004 followed an increase of 40% in 2003. Coho production here stands as the 5^th highest contribution in the Nestucca 5^th field for 2004. Average rearing density decreased from 1.4 fish/sq.m. to 0.94 fish/sq.m. as distribution spread to 3.7 total miles in the subbasin (0.5 miles further than 2003).  There were two observed peaks in spawning activity separated by a steep boulder incline and narrow bedrock gorge at RM 1. The lower zone appears more heavily used and Coho rearing densities here peaked at 2.0 fish/sq.m. (down from 3.0 fish/sq.m. in 2003).  50% of Bear Creek’s Coho were observed in this first mile. Above the narrow gorge a large supply of fine gravels and sand is retained and nearly 2 miles of excellent floodplain interaction exists. An older stand of conifers is present along much of the left side of the canyon. Rearing densities in this upper reach peaked over 2.0 fish/sq.m. in 2003 and again at 1.4 fish/sq.m. at the same location - RM 2.1. Three years of data suggest a consistent preference in spawning for these two sites. Trib. B, a low gradient canyon branching off to the left at RM 2.5, supported the greatest rearing densities of the Bear Cr. tributaries. 0.2 miles of small pools here averaged 3.6 fish/sq.m. Bear Cr. and neighboring Elk Cr. represent key anchor habitats for Coho in the mainstem Nestucca. Coho production in Bear Cr. exceeded Elk Cr. this year (by 27.2%) for the first time in the three year inventory. 2004 Coho distribution in Bear Cr. ended above a long stretch of bedrock chutes at a well established 15 foot high debris jam.

            1+Steelhead populations dropped 21% this year in Bear Cr. after a gain of 53% in 2003.  Their distribution was even throughout the survey. The occurrence of white mucous (potentially the parasite Apiosoma) was again noted on most 1+Steelhead and about half as many Cutthroat in Bear Cr. A radical decline in 0+trout was noticed in 2003 in Bear Cr. and, while the population rebounded slightly this year, abundance was only 61% of 2002 levels.

Beaver Cr.

            East Fk. Beaver is listed in the NNWC Assessment as exceeding the DEQ standards for summer water temperature. The West Fk. of Beaver remains below the minimum standard for temperature listing. The West Fk. of Beaver was not surveyed due to poor visibility. This included Tiger Cr., NF West Beaver and Trib A. The surveyor’s notes from 2002 indicate that juvenile salmonids were present and abundant (observations were common of fish disturbing the surface). This condition is believed to be caused by the extensive dunal forest habitats to the west which are drained by these tributaries. This is a unique geology within the Nestucca Basin and closely resembles conditions in the nearby Sand lake basin. The Access database treats the Beaver Cr. subbasin different than most other basins. By following the USGS naming protocols established on the 1:24,000 scale, Beaver Cr. terminates at the junction of West and East Beaver. To completely understand the current distribution profile of juvenile salmonids in the subbasin, the user will need to append the East Fk. data to the top end of the Beaver Cr. data set.

Beaver Cr. was the fourth highest producer of Coho in the Nestucca 5^th field in 2004. There was a dramatic reduction in Beaver Cr. Coho production in 2004 compared to the previous cohort (49%). An expanded estimate of 3,040 1+Steelhead were observed in the subbasin (13% decrease from the previous cohort). The Beaver Cr. and Elk Cr. subbasins are the only two Nestucca tributaries to exhibit lower Coho abundance in 2004 than in 2002, both registering reductions in abundance about three times greater than the 2004 basin-wide reduction of 15.8%. Cutthroat summer rearing continues to be on the rise (up 21%).

For the mainstem of Beaver Cr. from it’s confluence with the mainstem Nestucca to the confluence of the East and West Fk. (3.0 miles) there was an expanded estimate of just 415 summer rearing Coho parr and 705 1+Steelhead. This represents a significant and continued negative trend for both species in this reach when compared to 2003 totals - 1,930 Coho and 1,140 1+Steelhead, and 2002 totals - 2,940 Coho and 1,385 1+Steelhead. It should be noted that poor visibility through this reach under-estimates actual population sizes and complicates comparisons. This condition and its effects, however, have remained consistent during each year of survey. Most Coho spawning occurs upstream in East Beaver with the mainstem of Beaver Cr. supplying surplus rearing habitat for density dependant summer migrants as well as important winter rearing habitat. Density dependant migrants out of East Beaver were probably minimal this year due to the greatly reduced fry production and summer parr densities observed there. Distribution patterns for all species indicate that Beaver Cr. is not being utilized as upstream temperature refugia from the mainstem. This tracks well with the temperature data that suggests elevated stream temperatures may be a factor limiting water quality in Beaver Cr.

            East Fk. Beaver and its tributaries were producing an estimated 15,570 Coho in 2004, down from 30,180 in 2003. This accounts for 97% of the total Coho observed in the Beaver Cr. subbasin (understanding that the West Fk. was not surveyed). This quantifiable decrease in abundance is one of two large reductions in Coho escapement observed in the Nestucca basin in 2004 (Elk is the other). Average rearing density dropped from 1.5 fish/sq.m. to 0.54 fish/sq.m. with little change in distribution, a total of 10.1 miles (from the junction with mainstem Beaver). 2002 rearing densities increased from beginning to end of survey indicating a narrow (2.3 mile) distribution of adult spawners between RM 7.2 and 9.5. This zone expanded to 3 miles in 2003 with a few pools exhibiting rearing densities over 5 fish/sq.m., a fully seeded condition. 2004 density profiles exhibit a similar preference for this reach, a 1.1 mile zone with peak densities reaching 1.7 fish/sq.m. and the highest individual pool counts occurring just downstream. It is believed that most of this year’s loss in production was due to a lack of adult escapement.

             The larger pool surface areas just above the confluence with mainstem Beaver retained the majority of the subbasin’s production of Steelhead and Cutthroat. This distribution has remained identical through all three years. A potential parasitic infestation (resulting in spots of white mucous on the dorsal surface) was noted on most 1+Steelhead. Juvenile Chinook distribution ended by RM 4.2. No Access was granted by landowners between RM 1.3 and RM 2.5, therefore a portion of each species’ production has not been quantified for the subbasin (mileage was included in distribution graphics). A distinct lack of in-stream wood and streamside cover was noted throughout East Beaver until well into its upper reaches. Fish distribution ends in a series of steep boulder/debris jams.

Bear Cr. and Trib C appear to be the most important tributaries in the subbasin. Coho distribution in Bear Cr. extended for 2.4 miles in 2004 and the population here (785 expanded) accounted for 4.8% of the subbasin total. Coho rearing density here averaged 0.4 fish/sq.m. and peaked near RM 1 at 1.1 fish/sq.m. Good flows in this tributary, cold water temps., and adequate gravel reserves suggest a much higher production potential here for Coho. Population profiles suggest that Bear Cr. is providing important cold water temperature refuge for the mainstem of East Beaver. Low flows and small pools limit production in Trib C East Beaver. Production here in 2004 appeared minimal compared to 0.33 miles of moderate Coho rearing during the summer of 2003.   

 Bible Cr.

            Bible Cr. contained Coho to a point 0.9 miles above the confluence with the mainstem where adult passage is terminated at a 30’ waterfall. The expanded summer rearing estimate for Coho here has risen consecutively for all three years of the inventory, most notably between 2002 and 2003. Average rearing density has increased from 0.16 fish/sq.m. in 2002 to 0.8 fish/sq.m. in 2003 to 0.9 fish/sq.m. in 2004. Temperature dependent upstream migrations from the Nestucca mainstem appear to be the main source of summer rearing juveniles. The 63% loss in 0+trout abundance over the three year period appears also to be a noteworthy trend.

Boulder Cr.

            Boulder has a number of stream crossings that all appear to be negotiable to both adult and juvenile salmonids. Coho distribution over three years has increased by 0.7 miles on the mainstem to reach 3.0 miles total. Average rearing density rose from 0.24 fish/sq.m. in 2002 to 0.42 fish/sq.m. in 2003 and 0.45 fish/sq.m. in 2004. Juvenile Coho abundance here showed little change between 2003 and 2004 after a substantial growth of 163% between 2002 and 2003. Preferred spawning locations for Coho seem to be centered between RM 1.4 and RM 2.0. Turpy Cr. and the remaining tributaries could not be surveyed in 2004 due to a lack of funding and have not been included in this comparison. A distinct lack of in-stream wood and pool development is apparent in Boulder Cr. Fish distribution ends in steep boulders. Steelhead and Cutthroat numbers have shown little change through the three years of data while 0+trout have been on a steady decline, along with several streams in the basin, decreasing in abundance 74.4% since 2002.

 Cedar Cr.

            Cedar Cr. enters the mainstem very near the end point of Coho distribution in the mainstem Nestucca. Cedar contains only Coho that were upstream migrants from the mainstem seeking temperature refugia from the elevated stream temperatures in the upper mainstem. There is a boulder gorge in the mainstem just above the confluence of Cedar Cr. that has been opened to adult Coho migrants for the first time this year. Based on surveyor notes, it is doubtful that this gorge could be negotiated by juvenile Coho under low summer flow regimes. There are distinct water quality concerns in the headwater reaches that involve establishing a minimum summer flow for the Nestucca ecosystem and the current and quantifiable issue of elevated summer stream temperatures that are visible in the juvenile salmonid response in Cedar Cr. Cedar Cr. was contributing 30% of the mainstem flow at its confluence. There is a 5ft diameter culvert on the main Hwy with a 4ft. summer perch. This pipe is terminating upstream juvenile salmonid migrations that are very significant because of the poor water quality in the upper mainstem above the confluence of Cedar. Unfortunately the maintenance of this crossing would only result in an additional 500 ft. of accessible habitat because of a 20 ft falls just upstream that terminates all anadromous distribution. Summer juvenile Coho rearing density averaged 2.2 fish/sq.m. in 2004, 0.5 fish/sq.m. in 2003, and 1.2 fish/sq.m. in 2002. The few pools available in this short 0.26 mile reach appear to be greatly preferred to the mainstem by most juveniles in the area.

Clarence Cr.

            Coho distribution in Clarence Cr. for 2004 was the shortest of all three survey years – 0.33 miles. Totals for other species would likely have been greater had the survey continued further upstream. Coho production and density was again minor. It is probable that Coho spawning is occurring in Clarence Cr. as habitat conditions appear healthy. Upstream migration from the Nestucca mainstem is also likely. There was a definitive anadromous barrier (bedrock / boulder falls) 0.88 miles above the highway crossing. The survey began at the hwy crossing because access was denied in the stream segment from the hwy to the mainstem Nestucca. Physical barriers to fish passage in this segment are unknown. The hwy culvert was passable for juveniles and adults. Lineal distance is measured from the confluence with the Nestucca mainstem. It is not clear why the production potential present in Clarence Cr. has not been achieved. A steady decline in Steelhead is apparent through three years of data.

Clear Cr.

             The Clear Cr. survey began at the Jenks rd. crossing because access was denied from this crossing downstream to the mainstem Nestucca. Coho production here rose dramatically in 2003 from a greatly depressed condition in 2002 and decreased in 2004 by 26%. The distribution of summer rearing Coho has changed little in three years remaining between 0.84 miles in 2002 and 1.2 miles in 2003. Lineal distance is measured from the Jenks rd. culvert (easy passage). Average rearing density fell from 0.65 fish/sq.m. in 2003 to 0.3 fish/sq.m. in 2004. Flows in Clear Cr. were noted as clear and cold and gravel supplies abundant both below and above a narrow boulder/debris gorge, which has been passable each survey year. This data suggests that a much higher production potential for juvenile Coho could be realized from Clear Cr. The lower end of Clear Cr. would be extremely valuable distribution data if access could be sequestered because of the potential for significant upstream temperature dependant migrations of juveniles from the lower mainstem. 1+Steelhead numbers have dropped back to 2002 levels after a substantial increase in 2003.

Elk Cr.

This 2.6 mile reach of prime habitat ranked 3^rd in Coho production for the entire 5^th field during 2002 and 2003 surveys. Results from the 2004 inventory found Elk Cr. Coho production falling from 3^rd largest to 6^{th largest}, with Niagara Cr., Moon Cr., and Bear Cr. each out producing Elk Cr. Coho abundance in 2004 dropped to the lowest level of these three years, falling 51.4% from 2003 (more than three times the basin-wide 15.8% loss) and remaining 23.4% lower than 2002. Coho losses here in 2004 closely match the 49% decrease seen in the Beaver Cr. population lower in the basin, another one of the Nestucca’s most important tributaries for Coho production. In addition, Beaver Cr. stands as the only other subbasin besides Elk Cr. to record a lower Coho abundance in 2004 than in 2002. Coho abundance in Bear Cr., meanwhile, the subbasin directly adjacent to Elk Cr. and another major Coho producer historically, continued to rise by 14% and surpassed Elk Cr. abundance by 27.2%. 2004 declines in Elk Cr. are attributed mainly to a lack of adult escapement.

Coho production in Elk Cr. during 2003 reached levels above those commonly classified as seeded to capacity. Production increased by 58% over an already notable 2002 population and exhibited a remarkable average rearing density throughout the entire 2.6 mile distribution of Coho of 3.0 fish/sq.m. (peak density of 7.6 fish/sq.m.). Average rearing density during the 2004 survey dropped to 1.0 fish/sq.m. with a major spawning peak observed at RM 2.2 and a smaller peak resulting from upstream temperature dependant migrations from the Nestucca mainstem near the mouth. Rearing density during the 2002 survey averaged 1.4 fish/sq.m.

The lower Elk Cr. channel exhibits abundant boulders with little wood and gradually transitions to include finer gravels and debris jams. Several log structure sites are noted in the upper half that are continuing to function as high quality plunge pool habitats (summer) while effectively trapping mobile gravels. The lower gradients and fine gravel reserves surrounding RM 2 appear to be the main destination of adult spawners through all three years and the pools with structures retain large number of the offspring. In addition, the abundance and accessibility of cold water habitats available in lower Elk Cr. appear to be very attractive to juvenile Coho seeking temperature refuge from the mainstem Nestucca.

1+Steelhead and Cutthroat populations have remained moderate throughout the inventory, somewhat surprising considering the abundance of emergent Coho fry as an available food source. An estimated 75% of all 1+Steelhead observed, displayed signs of skin infection (mucous response) that may be indicative of a parasitic infestation. A mild occurrence was also noted in neighboring Bear Cr. 0+trout abundance in the subbasin has remained stable compared to many steep declines observed in nearby tributary habitats.

 Fan Cr.

            During 2002 and 2003 surveys Coho juveniles extended to the culvert crossing at RM 0.3 and terminated. The surveyor described the culvert crossing as excellent placement and no barrier to juvenile distribution. The last Coho, however, were observed in the pool below the culvert during both survey years. In 2004 Coho abundance in Fan Cr. dropped by 87% and distribution ended below the road crossing at RM 0.2. Indications are that Coho in Fan are mostly the result of upstream temperature dependant migrations from the mainstem.

 Farmer Cr.

            Farmer Cr. was an excellent contributor of cold water to the mainstem Nestucca. There is probably significant temperature maintenance provided to the mainstem from this tributary. There is a 2 ft. concrete dam at RM 0.44 that may be terminating the upstream distribution of juvenile salmonids from the Nestucca mainstem. This effect is strongly visible in the 2003 distribution data. Expanded estimates for Coho in Farmer Cr. remain well below potential, with a mix of spawning and upstream temperature dependant migrations from the mainstem taking place. A long reach of mixed species forest canopy, frequent debris jams, fine sandstone gravels, and deep pools extends from the last private residence to the multiple junction of tributaries above the last bridge (RM 2.8). Despite a minor decline in 2004, a positive trend in Coho abundance is apparent when compared with the 2002 population. This trend is supported by the 100% increase in lineal distribution observed in 2004, up from 1.4 miles to 2.8 miles. Highest counts for Coho in 2004 were observed in the lowest 1.8 miles of stream.   

             The dam did not appear to influence 1+Steelhead migrants to any significant degree during the surveys. The positive trend (98%) observed in 1+Steelhead abundance between 2002 and 2004 is complicated by the difference in lineal distance between the two years. It is likely that if the 2002 survey extended the full 2.8 miles of the 2004 survey that more 1+Steelhead would have been observed. An expanded estimate of 1+Steelhead found within the first 1.4 miles of the 2004 survey totals 425, still a 31% increase over the three year period. The 2003 survey extended 1.3 miles and the 45% decline observed in 1+Steelhead that year is regarded as a fairly accurate comparison. Most 1+Steelhead displayed signs of skin/mucous infection. There was a road culvert at RM 0.67 that had an 8 inch drop that also may have impacted upstream juvenile distribution. There was Japanese Knot weed observed along the stream corridor that could still be controlled (its abundance was limited).

Foland Cr.      

            2002 Coho distribution in Foland Cr. was limited to the first 0.26 miles and was believed to have originated solely from the upstream migration of juveniles from the Nestucca mainstem. It appears that spawning, in addition to upstream migration, may have occurred in 2003 and 2004 within Foland Cr. Surveys in 2003 observed a dramatic increase in population size – 1.5 miles of distribution (including the beginning of Trib. A) and a low average rearing density of 0.4 fish/sq.m.. Surveys in 2004 observed a significant 62.5% decline in Coho abundance while lineal distribution increased by 1 mile in Trib. A to reach a total of 2.4 miles within the subbasin. Average rearing density remains extremely low – 0.06 fish/sq.m. in the mainstem and 0.23 fish/sq.m. in Trib. A. This appears to be the maximum lineal distance available to anadromous migration at present within Foland Cr. as distribution in the mainstem ended at a large log/debris jam and at a permanently impassable 30’ falls in Trib. A. The consistent rise in abundance for trout species is again complicated by the increases in survey length for each year.

Ginger Cr.

            Maximum distribution for Coho in Ginger Cr. occurred in 2002 and was recorded as 368 feet. The small population here has shown little change in size and is probably the result of an upstream temperature dependant migration. There is a 6 ft falls just up from the mouth that probably truncates anadromous distribution. In addition, the culvert at the mouth of Ginger has a 1 ft. pour that probably terminates juvenile migrations.

Horn Cr.

            Coho have been broadly distributed in Horn during each survey year. Maximum lineal distance for each year’s population was recorded as 2.8 miles (2002), 4.4 miles (2003), and 3.4 miles (2004). Expanded summer rearing estimates dropped 41.4 % in 2004 after a gain of 88% in 2003, back to a level almost identical to 2002. Average rearing density has remained near 0.3 fish/sq.m. with peaks reaching 1.3 fish/sq.m.. Peak densities occur near the survey endpoint although most of the volume of the rearing population appears to center around the midpoint of the reach, approximately RM 1.4. Several excellent sites for spawning exist throughout Horn Cr. with easy access to the Nestucca tidewater. All the observed culverts were passable for both adults and juveniles. Coho production potential in Horn Cr. appears to be much higher than presently realized and to be limited mainly by adult escapement. 1+ Steelhead abundance here has been on a steady climb from the greatly depressed condition observed in 2002.

Limestone Cr.

            No Coho were present here in 2002. Surveys in 2003 revealed dramatic improvement in Coho escapement within the steep boulder habitat of this tributary. Coho distribution that year extended 2.2 miles in the mainstem and a total 0.6 miles up two side tributaries. Distribution then fell in 2004 down to 1.6 miles in the mainstem and 0.23 miles combined for Trib. A and Trib. B. Coho abundance likewise fell by 23%. Rearing density averaged 0.5 fish/sq.m. in the mainstem and  0.7 fish/sq.m. in Trib A for both years Peak density appeared low in the mainstem, 2.2 fish/sq.m. at RM 0.25, during 2003, and moved upstream to RM 0.7 (1.7 fish/sq.m.) in 2004. Some of the abundance in this reach is probably the result of upstream migration from the Nestucca mainstem. In Trib. A peak density dropped from 2.0 fish/sq.m. (RM 0.15) in 2003 to 1.2 fish/sq.m. (RM 0.04) in 2004. Distribution in Trib. A (16.5% of subbasin total) ends after 900 feet at an impassable waterfall. Distribution ends in the mainstem and Trib. B in steep boulders.

            Expanded Coho estimates in Limestone Cr. exhibit a positive trend over three years. A mix of spawning and upstream temperature dependent migration appears to be occurring. Spawning habitat appears poor to moderate throughout the subbasin with deep pools, steep gradients, and large rocks and boulders dominating the substrate. Rearing conditions for juvenile migrations out of the Nestucca mainstem appear excellent for similar reasons. The mainstem culvert appears to be in good shape and the cement steps easily passable.

Moon Cr.

            Moon Cr. enters the Nestucca near Blaine and contains the major fourth order tributary East Cr. This subbasin has been the site of extensive long term aquatic research and restoration conducted by the BLM and ODFW. The two streams were the site of a paired treatment and control study that evaluated the impacts of changes in winter habitat on smolt production. The historical abundance observed in the subbasin indicates that relatively low adult escapement of Coho has occurred during all three survey years. This statement is based mainly on the low average rearing densities recorded - 0.8 fish/sq.m. in 2003 and 2004. Adult escapement here appears to be on a steady increase, however, and has resulted in a positive three year trend in expanded Coho rearing estimates, despite minor reductions in 2004 (4%). Coho estimates rose 537% in 2003 from drastically low levels in 2002 and showed little change from this level during the 2004 survey. These increases have left Moon Cr. ranking third in the Nestucca 5^th field for 2004 Coho production. Moon Creek’s percent contribution to the 5^th field total Coho production has risen steadily from 2% to 7.8% and Coho abundance here in 2004 was equal to 14.6% of the Nestucca mainstem Coho population.

            Coho distribution in the subbasin continued to increase in both forks reaching 5.3 miles in Moon Cr. and 5.9 miles in East Cr. (compared to 4.7 miles in Moon and 5.4 miles in East Cr. in 2003). Moon Cr. densities remained at an average of 0.8 fish/sq.m. during the 2004 survey while East Cr. densities fell 44% to an average of 0.45 fish/sq.m.. Coho abundance fell 9% in mainstem Moon Cr. while East Cr. showed a 2% increase. The rise in abundance seen in East Cr. coupled with an increase in lineal distribution and a drop in rearing density was observed in several other streams throughout the basin in 2004. These figures appear to be well below the production potential existing in the subbasin. The aquatic habitats available in Moon and its tributaries indicate that Coho abundance could be substantially larger at full adult seeding. Subbasin totals for Coho appear to favor East Cr. with increasing tendency during all years (accounting for 56% of total subbasin production in 2004).

Multiple peaks in spawning activity appear in each fork. A gradually increasing density trend toward the end of distribution has been observed in Moon Cr. where rearing density peaked at 3.9 fish/sq.m. (RM 4.3) in 2003 and at 3.2 fish/sq.m. (RM 3.8) in 2004. Rearing density averaged 1.5 fish/sq.m. (full seeding) from between RM 3.7 and RM 5.2 in 2004. Average rearing density in East Cr. fell to 0.45 fish/sq.m. in 2004 and the Coho population here was observed more evenly distributed in the lowest 4.2 miles of survey. A peak of 1.4 fish/sq.m. was observed in 2004 at RM 3.1 compared to the 2.6 fish/sq.m. observed in this zone last year. Trib. G (Trib. C in 2003 data) appears to be the most productive of the many East Cr. tributaries with a 2004 expanded estimate of just 140 Coho (90 in 2003), 1000 feet of lineal distribution (605 feet in 2003), and an average rearing density of 1.4 fish/sq.m. (2.2 fish/sq.m. in 2003). This low gradient stream joins East Cr. at RM 3.8 and accounted for 78% of all tributary Coho in the East Cr. subbasin for 2004 (90% for 2003). Pools resulting from habitat restoration logs accounted for most of the summer rearing population in upper East Cr. Coho Distribution in Moon Cr. was terminated by a series of debris jams while an increasing abundance of bedrock terminated distribution in East Cr. Coho production in the Moon Cr. subbasin continues to be limited mainly by adult escapement.

Both Steelhead and Cutthroat production has remained significant in this subbasin throughout the three year inventory, despite significant reductions in 2003. The majority of each species has occurred in the lowest two miles of each branch during the surveys. The dramatic reduction in 0+trout abundance observed in 2003 showed little correlation to the increases seen in 2004 1+Steelhead and Cutthroat populations. The increases in lineal distance for each survey is relatively insignificant in this case since the large majority of these species is consistently found in the lower reaches of each stream. This data suggests significant migration of 1+trout into Moon Cr. from other areas of the basin. A mild occurrence of skin infections on many 1+Steelhead and Cutthroat, similar to other upper Nestucca tributaries, was observed in Moon Cr. 

Niagara Cr.

            Niagara exhibits tremendous salmonid production potential with easy access to high quality spawning substrates for 4.3 miles in the mainstem to a potential barrier at a bedrock falls and another 2.1 miles in Beulah Cr. to a major fork where gradients become limiting. Adult escapement is blocked early in Pheasant Cr. by a bedrock falls after 0.6 miles and multiple log jams. In 2002 Coho were only utilizing 2.4 miles of mainstem habitat, with distribution terminating just above the confluence of Pheasant Cr., and only 0.7 miles of Beulah Cr.  During the 2003 survey Coho abundance rose substantially (265%) and distribution extended through the remaining 1.9 miles of mainstem habitat up to the falls and through the total 2.1 miles of productive habitat in Beulah Cr.  2004 surveys found a decrease in summer rearing distribution, down to 3.8 miles in the mainstem and 1.6 miles in Beulah Cr., while expanded estimates continued to climb by 16.4%. Niagara Cr. was one of only 3 subbasins (including Bear and Powder) within the 5^th field to experience two years of continuous growth in Coho production. Its rise in percent contribution to 5^th field total Coho production, from 3.1% in 2002 to a notable 8.6% in 2004, has left this subbasin as the second largest Coho producer in the Nestucca 5^th field (following only the Nestucca mainstem). Indications are that potential carrying capacity for this system remains substantially higher.

            About 85% of the subbasin Coho population was found in the mainstem during each survey year. Average rearing density there climbed from 0.44 fish/sq.m. in 2002 to 1.1 fish/sq.m. in 2003 and showed little change in 2004. A peak density of 1.9 fish/sq.m. was achieved in multiple locations throughout the lower 2 miles of mainstem in 2003. Peak density in 2004 climbed to 3.3 fish/sq.m. and moved upstream slightly to RM 2.6. The bulk of the subbasin population during these two years was found downstream of these peak mainstem density readings. Average rearing density and lineal distribution for Coho here indicate a strong opportunity in mainstem Niagara for continued production increases. The only limiting factor to summer production appears to be adult escapement.

Beulah Cr. exhibited two spawning peaks in 2003, the first at RM 0.6 (1.3 fish/sq.m.) and the second at RM 1.4 (2.5 fish/sq.m..). Rearing density averaged 0.9 fish/sq.m. throughout 2.1 miles of distribution, an increase of 1.4 miles over 2002. Coho production in Beulah Cr. rose 309% in 2003 and accounted for 13% of the subbasin total. Average rearing density dropped to 0.55 fish/sq.m. in 2004 and expanded estimates here fell 32% (accounting for 7.5% of the subbasin total). Peak density reached 1.4 fish/sq.m. at RM 0.25.

Most of the increase within the subbasin for the 2004 summer Coho population occurred in the lower Niagara mainstem and in Pheasant Cr. There appears to have been a spawning event all three years in the lower few hundred feet of Pheasant Cr. and a log jam barrier with a small bedrock falls just above this point currently terminates upstream distribution of adult Coho (Steelhead were observed above this jam). Upstream temperature migration out of mainstem Niagara Cr. also appears to be contributing to the high densities found in this stream. An average rearing density of 3.4 fish/sq.m. was observed here in 2003 and another high reading of 3.5 fish/sq.m. was repeated here in 2004. The expanded estimate of 560 juvenile Coho for 2003 grew 223% in 2004 to reach 1,810 juvenile Coho. The 2004 Coho population here was 2% larger than in Beulah Cr. with only 1/3 of the lineal habitat and the average rearing density for Coho here was larger than any individual peak density in the rest of the subbasin. Summer rearing in Pheasant Cr. accounted for 8.6% of the subbasin total.

1+Steelhead abundance in the subbasin appears similar between all three surveyed years. Cutthroat abundance showed little change between 2002 and 2003 considering this increase in survey distance then doubled between 2003 and 2004 while survey distance in the subbasin decreased by 1 mile total. Mild skin infection was noted on several 1+Steelhead during all years of inventory.

Powder Cr.

            Powder Cr. contained Coho that extended to a point 2.8 miles above the confluence with the mainstem. This represents a continued increase of 0.2 miles of distribution in the mainstem as well as an additional 0.4 miles in the Left Branch where distribution totaled 1 mile. No Coho were seen in the Left Branch in 2002. Shueble Cr. supported 0.5 miles of summer Coho rearing for the first time in the three year inventory while the Dahl Fork contained no Coho for the third straight year. Expanded estimates for summer rearing Coho were extremely low here in 2002, totaling just 545 Coho for the entire subbasin. This figure increased by 798% in 2003 and again by 42% in 2004, the greatest increase seen in the Nestucca 5^th field during a year when Coho numbers fell 16.4% basin-wide. Powder Cr. was one of only 3 subbasins (including Bear and Niagara) to experience continued growth in its Coho population this year.    

            The average rearing density in the mainstem rose from 0.14 fish/sq.m. in 2002 to 0.86 fish/sq.m. in 2003 and fell slightly to 0.7 fish/sq.m. in 2004. An average rearing density of 0.7 fish/sq.m. in the Left Branch during 2003 showed no change in 2004. Two peaks in spawning density were observed in the mainstem during the 2003 survey, the first at RM 1.1 (1.7 fish/sq.m.) and the second at RM 1.8 (1.1 fish/sq.m.). High numbers of upstream migrants from the mainstem Nestucca were seen in the lowest pools. During 2004 surveys, upstream temperature dependant migrations from the mainstem were observed for at least 1600 feet of stream and averaged 1.8 fish/sq.m., a spawning peak was observed at RM 1. Rearing density in the Left Branch peaked at 1.4 fish/sq.m. at the end of distribution (RM 0.6) in 2003 and at 1.3 fish/sq.m. at RM 0.45 and RM 0.9 in 2004. Coho production in the left branch accounted for 6% of the subbasin total in 2003 and 12.4% in 2004. Coho distribution in the mainstem ends in a series of steep waterfalls and in low flows and wood jams in the Left Branch.

            It looks as though some Coho spawning may have taken place in Shueble Cr. this year along with a small occurrence of upstream migration out of Powder Cr. A small population of juvenile Coho (375 expanded) were observed here in an average rearing density of 1.1 fish/sq.m. that extended a total of 0.5 miles. Density peaked at 1.9 fish/sq.m.. Distribution in this stream ended in steep gradients after multiple divisions of flow among tributaries. The Dahl Fork of Powder Cr. appears to be limited by an immediate occurrence of large boulders and steep gradients.

            In spite of dramatic improvements in the system, rearing densities remain below capacity throughout all of the reaches in the Powder Cr. subbasin. A noticeable lack of fine spawning gravel in the system may be a significant limiting factor in Powder Cr.     1+Steelhead have maintained a low but stable abundance in the system while Cutthroat have exhibited a continuous increase. There was a white mucous observed on both Steelhead and Cutthroat in Powder Cr. throughout the inventory that appeared similar to the infections sighted in several other upper Nestucca tributaries. These occurrences appeared to decrease substantially during the 2004 survey.

Slickrock Cr.

            The one mile survey here continued to a 60 ft. bedrock falls classified as a definitive anadromous barr