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

RAPID BIO-ASSESSMENT 2002

INTRODUCTION

A Rapid Bio-Assessment inventory was conducted for the Nestucca-Neskowin Watershed Council (NNWC) during the summer of 2002. This inventory included the Nestucca, Neskowin and Sand Lake basins. 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 it’s tributaries (mainstem Nestucca begins at the confluence of Beaver Cr.). 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 6th field level in response to restoration and watershed management issues.

The escapeme! nt of adult Coho in all of the surveyed basins and ocean tributaries during the 2001 brood year was still insufficient to adequately seed the summer habitat currently available on a watershed scale throughout the four 5th 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 12 years occurring in 2001. The Nestucca OCN Coho estimate for 2001 based on randomly selected adult spawning surveys was 3,940 and the Neskowin / Sand Lake estimate was 71. These estimates compared to escapement estimates of 1,171 and 0 for the year 2000 exhibit dramatic increases in abundance and are indicators of recent improvement in ocean conditions. ODFW’s long term SRS monitoring of adult Coho escapement ! suggests that the 12 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 2002 still does not describe all of the accessible and suitable spawning and rearing habitats for salmonids because of continued under escapement.

The 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 database contains the results of 175 stream miles that were surveyed. This includes the full extent of Coho distribution in the Sand Lake (10 miles), Neskowin (13 miles) and Nestucca basins (152 miles) except for the segment of the mainstem Nestucca between the head of tidal influence and the confluence of Beaver Cr. and the majority of West Beaver (inadequate visibility). 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 33 days between surveys of the mainstem Nestucca between the first 13.4 miles surveyed above the confluence of Beaver Cr. and the remaining 19.6 miles surveyed 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 (2nd 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 surveyors 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 2nd 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 a 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 was 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 was 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. Latitude and longitude values were collected with a "Garmin 2 plus" GPS receiver with an external antenna. Many end point determinations were not verified with GPS coordinates because of the lack of reception.

GENERAL OBSERVATIONS

The distribution and abundance of Coho juveniles observed during the 2002 summer field season was the result of a wide spread increase in adult escapement during 2001. We are assuming that the distribution of Coho during the summer of 2002 was greater than the distribution of Coho that was present in 2001 based on the 243% increase in the abundance of OCN Coho adults in the last two years. This increase was very significant in the Neskowin and Sand Lake basins where observed adults in ODFW’s Stratified Random Sample (SRS) increased from 0 to 71 between the years 2000 and 2001. Most habitats were not seeded to capacity in the inventoried systems and there is still extensive summer habitat available to salmonids that is currently under utilized. There were some exceptions where sections of Baxter, Bear, East Beaver, Elk, Testament, Louie, Sourgrass and Trib C of the Nestucca exhibited a fully seeded condition for Coho. 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 was in fact an excellent example observed in the Little Nestucca (Baxter Cr.) during the 2002 inventory of a stream reach that far exceeded the level of 1.5 fish/sq.meter of pool surface area. 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 2002 Nestucca / Neskowin cd).

Distribution profiles
The distribution of juveniles and their observed rearing densities for each surveyed reach provide a bas! is 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 2002 field season. Trend analysis will become an important aspect of this review with the subsequent year to year replicates planned for 2003 and 2004.

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 is currently being developed by the USFS 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 sub basin 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.). 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 drive! r 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 (ie., 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 data base 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 1. 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 1 contains this comparison, exhibiting the variation in average density based on the selection of different starting points.

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 survey! ed 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 observation 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 5th fields. Each of these 5th fields has been summarized separately. The expanded juvenile salmonid estimates are also broken down into 5th field estimates (ie, the mainstem Nestucca does not include the production from the Little Nestucca).

Nestucca

! The Nestucca mainstem was not surveyed below the confluence of Beaver Cr. because of compromised visibility resulting from suspended solids and algae. There is significant juvenile salmonid rearing that occurs in these 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 4th or 5th field production estimates below.

The following table represents the contribution in salmonid production (by species) from each tributary to the Nestucca 4th field Watershed. 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. These estimates greatly under estimate the standing crop of 0+, Steelhead and Cutthroat because a large component of the basins 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.

(Table 2)
Stream Coho % Total 0+ % Total Sthd % Total Cut % Total
Nestucca (main) * 82,395 43.4 * 36,700 27.4 * 8,185 31.7 * 5,685 22.9
Bays 395 1,765 1.3 435 1.7 235
Bear * 9,155 4.8 * 11,810 8.8 715 2.8 755 3.1
Beaver * 28,145 14.8 * 25,915 19.3 * 3,925 15.! 2 * 3,160 12.7
Bible 365 1,080 145 200
Boulder 560 2,830 2.1 230 395 1.6
Cabinet 0 35 0 15
Cedar 545 145 0 35
Clarence 85 295 50 260 1.0
Clear 140 570 65 665 2.7
Elk * 14,970 7.9 4,780 3.6 575 2.2 375 1.5
Fan 135 115 10 40
Farmer 295 1,345 1.0 325 1.3 345 1.4
Folland 40 260 40 95
George 60 315 45 80
Ginger 40 190 0 5
Horn 1,545 1,860 1.4 10 510 2.1
Limestone 0 390 50 115
Little Nestu * 30,555 16.1 * 7,580 5.7 * 1,735 6.7 * 4,260 17.1
Mina 0 110 15 10
Moon 3,140 1.7 * 16,375 12.2 * 3,000 11.6 * 2,520 10.1
Niagra 4,940 2.6 5,360 4.0 835 3.2 510 2.1
Powder 545 1,130 180 335 1.3
Sanders 0 0
SlickRock 1,525 880 160 240 1.0
Smith 10 35 0 185
Testament 5,535 2.9 2,410 1.8 195 225
3 Rivers 995 7,390 5.5 * 4,750 18.4 * 2,790 11.2
Tony 10 105 15 55
Town Lake 0 175 0 30
Trib A 0 40 0 0
Trib B 0 0 0 0
! Trib C 3,565 1.9 1,340 1.0 80 140
Trib D 5 30 5 85
West 325 460 75 425 1.7
Wolfe 0 160 5 95

Basin Total
190,020
96.1
133,980
95.1
25,855
94.8
24,875
93.5

* Highlighted estimates represent the top 5 producers by species and age class for 2002
(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.

(Table 3)
Expanded Nestucca (5th field) Estimates of Juvenile Salmonid Production
Survey Year Coho 0+ Sthd Cut
2001 159,465 126,400 24,120 20,615
The table above deletes the production occurring in the Little Nestucca and facilitates a review by 5th field.

Mainstem Nestucca

(Table 4)
Expanded Mainstem Nestucca Estimates of Juvenile Salmonid Production
Survey Year Coho 0+ Sthd Cut
2001 82,395 36,700 8,185 5,685
% 5th field 52% 29% 34%* 28%*
* These percent contributions would be significantly higher if the rearing occurring in the
lower 14 miles of mainstem were included.

The Nestucca mainstem from the confluence of Beaver Cr. to the end of Coho distribution at the confluence of Cedar Cr. was the single most productive component of the entire 5th field for all species of juvenile salmonids. This segment of mainstem rearing habitat encompassed approximately 33 lineal miles and exhibited by far the greatest production potential in the 5th field. Many of the smaller order tributaries that contribute flow to the mainstem truncate fish distribution with definitive an! adromous barriers, steep gradients or elevated summer temperatures. The maintenance of the water quality (summer flows, temperature, DO) in the mainstem is therefore paramount in 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 appears to be concentrated above the confluence of Beaver Cr. with very limited abundance in the mainstem below the confluence of Boulder Cr. There was a distinct transition in water quality observed below the confluence of Boulder. Sticklebacks appeared in the mainstem inventory at this junction, the level of suspended particulates in the water column increased and algal growth was distinctly more abundant on substrates. The majority of the mainstem Coho rearing was concentrated above the confluence of Niagra Cr. This results in a productive corridor of approximately 18 miles from Niagra to the end of distribution at Cedar Cr. Some of the mainstem pools in this reach were summer rearing between 800 and 1000 Coho juveniles each, with densities continually increasing to almost the end of distribution. Coho 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 average rearing density for all mainstem pool habitats within the distribution of Coho was 0.15 fish/sq.m with a peak density of 2.2 fish/sq.m. Mainstem juvenile densities were very high above the confluence of Elk Cr. indicating that the mainstem spawning of adult Coho in this reach could be significant.

Steelhead distribution was distinctly different with peak densities occurring lower in the surveyed section between a point 10 miles above the confluence of Beaver and 26 miles above the confluence of Beaver. Because of the increasing size of the pool surface areas progressing downstream from the headwaters the lower densities of Steelhead observed actually result in higher production. There were no pools above the 26 mile mark (from the confluence of Beaver Cr.) with more than 10 Steelhead observed. In comparison, many pools just above the confluence of Beaver were rearing between 40 and 60 older age class Steelhead. Indications are that large numbers of Steelhead are summer rearing in the mainstem well below the confluence of Beaver Cr. with a steady decline in the number/pool as the distance increases above the confluence of Beaver. 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 the survey did not include the mainstem below the confluence of Beaver it was not possible to assess whether this trend of increasing abundance would have continued below the confluence of Beaver Cr.

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 Beaver Cr. Very large (18 inch) resident Cutthroat were common in this lower mainstem. They were closely associated with concentrations of juvenile Chinook and were preying heavily on these salmonids (distended stomachs and stalking behavior). The distribution of these older age class Cutthroats may be closely linked with the seasonal distribution of Chinook fry in their steady progression towards the estuary. There was an expanded estimate of 65,505 juvenile Chinook observed in the inventory above the confluence of Beaver Cr. Their distribution was also very similar to that observed for Steelhead and Cutthroat with decreasing abundance above the confluence of Beaver Cr. In addition, very few Chinook were observed above a point 26 miles from the confluence of Beaver Cr.
Adult Spring Chinook, Summer Steelhead and a single Chum Salmon and a sing! le Sockeye Salmon were observed within the mainstem inventory. The highest single resting pool count for adult Summer Steelhead was 22.

Bays
Bays Cr. exhibited spawning peaks in two separate locations, indicating that at least two Coho redds were present. The expanded summer rearing estimate for Coho parr was 395 with an average density of 0.1 fish/sq.meter and a peak density of 0.31 fish/sq.meter. There were Steelhead also present rearing in the subbasin that were broadly distributed. The surveyors mention damage at the inlet side of the culvert that is 450 ft above pool 1. This damage resulted in a turned up lip on the pipe that may impact the upstream movement of juveniles. The other mainstem culvert in the tributary was classified as negotiable for both adults and juveniles.

Bear
Bear Cr. exhibited an expanded summer rearing estimate for Coho of! 9,155. The average rearing density was 1.5 fish/sq.meter and the observed peak density was 6.2 fish /sq.meter. This suggests that Bear was nearly seeded to capacity. In addition, rearing densities far exceeded the presumed level of full seeding (1.5 fish/sq.meter) in the first 1.3 miles of their distribution. There appeared to be a key anchor habitat reach located in the 1/3 mile section below a boulder incline (RM 0.8) where densities of all salmonids soared above assumed full seeding levels.

Beaver
East Fk. Beaver is listed in the NNWC Assessment as exceeding the DEQ standards for water temperature. The West Fk. of Beaver remains below the minimum standard for temperature listing. The West Fk. of Beaver was nearly unsurveyable because of extremely poor visibility for snorkeling. This included Tiger Cr., NF West Beaver and Trib A. The surveyors notes indicate that juvenile salmonids were ! present and abundant (observations were common of fish disturbing the surface). The Access database treats the Beaver Cr. subbasin different that 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. is a major producer for Coho. By comparison, Beaver Cr. alone produced Coho at a level equal to the entire Little Nestucca subbasin and supported a level of production that was 34% of the mainstem Nestucca total.

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 2,940 summer rearing Coho parr (9% of the Beaver Cr. production). In addition, this section of Beaver had an expanded estimate of 1,385 Steelhead (35% of the subbasin total). 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 it’s tributaries were producing an estimated 24,915 Coho, 89 % of the Coho observed (understanding that the West Fk. was not surveyed) in the subbasin. The average rearing density was 0.61 fish/sq.m and the observed peak was 8.37 fish/sq.m. Distribution extended 11 miles from the confluence of mainstem Beaver. The 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. The larger pool surface areas just above the confluence with mainstem Beaver retain the majority of the subbasins production of Steelhead. Bear Cr. was a minor contributor of East Beavers production (1%) and no spawning activity was detected for Coho.

Bible
Bible Cr. contained Coho to a point 0.7 miles above the confluence with the mainstem. The expanded summer rearing estimate for Coho was 365. The average rearing density was 0.16 fish/sq.m and the peak was 0.30 fish/sq.m. Bible Cr. would have had at least a single spawning pair of Coho. Steelhead were also present.

Boulder
Boulder has a number of stream crossings that all appear to be negotiable to both adult and juvenile salmonids. The third culvert upstream from the mouth appears to be rusting out and may need to be reviewed as a maintenance item. Coho distribution continued to a point 2.3 miles above the confluence of the mainstem Nestucca with an average rearing density of 0.19 fish/sq.m and a peak of 1.18 fish/sq.m. The expanded summer rearing estimate for Coho was 560. Steelhead were also present.

Cedar
Cedar Cr. enters the mainstem very near the end point of Coho distribution in the mainstem Nestucca. Cedar contained 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 that terminated adult Coho migrants in 2001. 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 was contributing 30% of the mainstem flow at it's confluence. The! re 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. Cedar contained an expanded estimate of 545 Coho and no Steelhead were observed.

Clarence
Steelhead and Coho were present to a narrow bedrock gorge at a point 0.4 miles above the hwy crossing. Coho production was minor with an expanded estimate of only 85 summer parr. These Coho appear to be the progeny of a spawning pair in Clarence Cr. There was a definitive anadromous barrier (bedrock / boulder falls) 0.88 miles above the hwy crossing. The survey began at t! he hwy crossing because access was denied in the stream segment from the hwy to the mainstem Nestucca. The hwy culvert was passable for juveniles and adults.

Clear
The Clear Cr. survey began at the Jenks rd. crossing because access was denied from this crossing downstream. Coho were present in low numbers for the next 0.84 miles with an expanded estimate of 140 summer parr. 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.

Elk
Elk Cr. contains very high rearing densities of Coho to the end point of anadromous distribution at RM 2.6 (large falls, definitive barrier). The expanded estimate of summer rearing Coho parr was 14,970. The average rearing density was 1.33 fish/sq.m and ! the peak density was 2.64 fish/sq.m. This level of abundance was nearly seeded to capacity for Coho and rated as the 3rd most productive subbasin in the 5th field (following the mainstem Nestucca and Beaver Cr.)

Fan
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 were however observed in the pool below the culvert. The total expanded Coho estimate for the tributary was 135 with decreasing densities as the survey progressed upstream.

Farmer
Farmer Cr. was an excellent contributor of cold water to the mainstem Nestucca. There is probably significant temperature maintenance delivered 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 mainstem. This was not apparent in the distribution of juvenile Coho because the mainstem Nestucca was not rearing significant numbers of Coho this far downstream. There was however, indication that upstream Steelhead migrants from the mainstem were present in the subbasin. The dam did not appear to influence these migrants to any significant degree during 2002 (see distribution graphic, dam is just above pool #5). Coho were observed to a point 1.3 miles above the confluence with the mainstem Nestucca. There was an expanded estimate of 295 summer rearing Coho at an average density of 0.10 fish/sq.m. The Coho observed were unusually large and had the appearance of fed hatch box recruits. Another possible explanation for this unusual size was an exceptionally early adult spawning event. There was a road culvert at RM 0.67 that had an 8 inch drop that also may have impacted upstream juvenile distribution (a minor concentration of Steelhead was noted below the culvert. There was Japanese Knot weed observed along the stream corridor that could still be controlled (it’s abundance was limited). There was also some unusually large resident rainbow observed in Farmer Cr. (14 inch). There were no other large rainbow observed anywhere in the Nestucca basin. Cutthroat densities were excellent and increased to high levels near the end point of the survey.

Folland
There was a total of 40 Coho (expanded estimate) observed in Folland Cr. Their distribution was limited to the first 0.26 miles and they originated from upstream migrations from the mainstem. There was no spawning peak observed for Coho. There were also a few Steelhead present and they also appear to be upstream migrants from the mainstem.

George
There was an expanded summer rearing estimate of 60 Coho ju! veniles observed. It is unclear from the distribution pattern whether these fish originated from a spawning event or from an upstream temperature dependant migration from the mainstem. Subsequent inventories should help describe the status of juvenile salmonids in George Cr.

Ginger
The expanded estimate for summer Coho parr was 40 for the subbasin. There were no Steelhead observed rearing in Ginger Cr. Coho extended only 400 ft and were probably the result of an upstream temperature dependant migration. There was a 6 ft falls just below pool #5 that probably truncates anadromous distribution. In addition, the culvert at the mouth of Ginger has a 1 ft. vertical plunge that probably terminates juvenile migrations late in the season. Horn Coho were broadly distributed in Horn to a point 2.7 miles above the head of tidal influence. The expanded summer rearing estimate for Coho was 1,545. The average rearing density was 0.16 fish/sq.m and the peak was 0.58 fish/sq.m. All the observed culverts were passable for both adults and juveniles and the Coho observed were unusually large. There was only a few Steelhead observed (10 expanded) in the survey. The gravels were classified as abundant and the subbasin has much greater production potential than observed for Coho. There were at least two distinct spawning peaks observed, one near RM 1.4 and the other at the end point of Coho distribution.

Moon
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. Coho were distributed broadly (5.0 m! iles in Moon and 4.7 miles in East) in very low densities. The historical abundance’s observed in the subbasin indicate that relatively insignificant adult escapement of Coho occurred during 2001. The expanded estimate of summer rearing Coho parr for the subbasin was 3,140. The average rearing density throughout the combined distribution in East and Moon was only 0.09 fish/sq.meter. There were at least two spawning peaks observed in East Cr. and only one in upper Moon. Both Steelhead and Cutthroat production were significant in this subbasin. On East Cr., Coho distribution ended at a culvert with a 7 inch drop into a 5 ft deep plunge pool. The culvert was inclined and 120 ft. long. The site did not appear to be a barrier for adult migrants and upstream juvenile migrations are probably not a factor at this site because of the abundance of cold water refugia in mainstem East Cr.

Niagra
Niagra exhibits tremendous salmonid production potential with open access to high quality spawning substrates for 4.3 miles to a potential barrier at a bedrock falls. Currently Coho are utilizing 2.4 miles of this habitat and their distribution terminates just above the confluence of Pheasant Cr. The expanded estimate of summer rearing Coho parr was 4,940 and the average rearing density was excellent at 0.44 fish/sq.meter. There appeared to have been a spawning event in the lower few hundred feet of Pheasant Cr. and a log jam barrier just above this point currently terminating upstream distribution of adult Coho (Steelhead were observed above this jam). Buelah Cr. exhibited a single spawning peak near the end point of Coho distribution at 0.7 miles. The surveyor indicated that there was no barrier to continued migration in Buelah which suggests that the Niagra subbasin as a whole is primarily limited by depressed adult escapement. 

Powder
Powder Cr. contained Coho that extended to a point 0.9 miles above the confluence with the mainstem. Coho distribution ended below the confluence of Shueble Cr. and therefore Shueble contained no Coho. The expanded estimate of summer rearing parr was 545 and there was only one significant spawning peak observed near the end point of distribution. The average rearing density was minor at 0.14 fish/sq.m. Steelhead were also present in the system. There was a white mucous observed on both Steelhead and Cutthroat in the tributary that may be an indication of the presence of parasites.

Sanders
Sanders contained neither Coho or Steelhead juveniles. The stream was primarily confined to a pasture trench for approximately 2 miles and only Sticklebacks were observed.

Slickrock
The survey continued to a 60 ft. bedrock falls classified as a definitive anadromous barrier at RM 1.0 . The Culvert at the mouth exhibited a 2 ft. vertical pour and was classified as a definitive juvenile barrier. Coho distribution actually terminated 15 pools downstream of the falls at a series of 6ft. bedrock slides. The expanded summer rearing estimate for Coho was 1,525 and the average density was high at 0.72 fish/sq.m. Mucous was also commonly observed on 1+ and older Steelhead and Cutthroat juveniles which may indicate the presence of parasites.

Smith
The Smith Cr. survey began at a submerged culvert low on agricultural land but above the confluence with the mainstem Nestucca. This culvert was not a passage problem for juveniles or adults. The next culvert crossing at pool #7 was a 4 ft perched pipe that was 4 ft in diameter. Coho were observed in the pool below the culvert and no higher. The culvert functions as a definitive barrier to the upstream temperature dependant migration of juveniles. There did not appear to be any evidence of a Coho spawning event in Smith and the observed Coho were likely migrants from the mainstem. The Coho were exceptionally large and benefiting from the aquatic environment. The surveyors assessment of the conditions above the culvert suggests that salmonids would benefit from improved access at this road crossing (gravels, increased gradient).

Testament
Testament was a major producer of juvenile Coho during 2002. The expanded summer rearing estimate for Coho was 5,535 and the average density was 1.24 fish/sq.m. (a level nearly fully seeded within their distribution). Coho extended to RM 3.2 and could have been distributed significantly higher in the tributary (open access). There was a 1300 ft. boulder gorge that began at RM 0.9 that maintained significantly lower densities of Coho and Steelhead. The Hwy culvert was in excellent condition and passable for all age classes. Steelhead distribution graphics suggest that upstream temperature dependant migrations from the mainstem Nestucca may be occurring. Verification of this movement will be more appropriate with supplemental years of data.

Three Rivers
Three Rivers contains an ODFW production facility at Cedar Cr. that raises Spring Chinook, Summer and Winter Steelhead. Because the location of this facility is low in the Three Rivers subbasin, there is a trap and fish weir in place to trap adults of hatchery origin that compromises the unimpeded upstream migration of wild anadromous migrants. It is important to understand that the current genetic selection, production potential and distribution of OCN Coho, wild Winter Steelhead, wild Fall Chinook and Searun Cutthroat in the Three Rivers subbasin is partially dictated by the hatchery practices occurring at the site of this! weir. All anadromous populations exhibit broad run timing profiles that overlap with other species and subspecies. The peaks of these profiles typically differ but there is significant overlap in the early and late components of each of these runs. For the Cedar Cr. site, the weir is passable from the first significant fall freshet to a point when hatchery Winter Steelhead adults first appear. It is this line of demarcation between fall Chinook and winter Steelhead (variable from year to year and dependant on flow regimes) that truncates the late spawning component of both the wild Fall Chinook and the late OCN Coho populations. The effect of this demarcation being most significant for OCN Coho because the potential for adult spawner escapement exists in many coastal Coho systems into the month of February.

Three Rivers exhibited only minor escapement for OCN wild Coho for the 2001 brood year. The expanded estimate of summer rearing Coho parr for the entire subbasin was 995. The majority of these juveniles (77%) were observed in Alder Cr. with the only exception the 35 (expanded) juveniles observed in Pollard Cr. and the 190 (expanded) observed in the mainstem (primarily below the confluence with Alder). Spawning appeared to have occurred at two different sites in the upper end of Alder and possibly the Coho juveniles observed in Pollard were the result of a spawning event also. Based on equations calculated by Nickelson and Lawson (1998) the expanded juvenile Coho estimate for the Three Rivers subbasin represents an adult escapement of something on the order of 6-10 adults (assuming 1:1 male / female ratio). This limited production compared to the abundance of high quality habitat available for OCN Coho suggests that some of the largest cost / benefit ratios exist in this subbasin for restoring proper function and boosting OCN Coho pro! duction (see recommendations).

Steelhead juveniles were present in densities similar to those observed in other subbasins, indicating that escapement is occurring. The concerns for Steelhead are two fold; does the present escapement represent the diversity that exists in run timing and what are the genetic origins of the adults passed at the Cedar Cr. weir (hatchery / wild interactions). Observations of external mucous on Steelhead juveniles was common, with individuals exhibiting less than 10% impact on body surface area. This mucous is probably a response to external parasites (sp. undetermined). Mucous observations occurred both above and below the Cedar Cr. weir.

Cutthroat were present throughout the subbasin and classified as abundant in the upper of Alder Cr. The higher densities observed were located in the identical locations of the highest densities observed for ! Coho juveniles. This relationship is common and an indication of the value of anadromous salmonids to resident populations.

There were Chinook juveniles observed in the mainstem of Three Rivers (primarily below the Cedar Cr. facility) that exhibited accelerated growth characteristics and also were adipose clipped. These fish may have been residualizing from the Rhodes Pond release. The total expanded estimate of abundance was minimal (<100) and probably insignificant to the function and survival of other salmonid species.

Tony
Tony Cr. contained an expanded estimate of only 10 Coho parr. These juveniles were the result of upstream temperature dependant migrations from the mainstem Nestucca. The surveyor identified the habitat in Tony as poorly suited for Coho at least within the extent of the survey (Rapid dominated habitats with large substrates). Steelhead! were present in low numbers

Town Lake
There were no Coho or Steelhead observed in the Town Lake tributary. The survey was initiated just above town and proceeded 1000 ft. to an end point. The substrates were dominated by sand and silt. Some shallow gravels were present.

West
West Cr. contained an expanded summer rearing estimate of 325 Coho parr. These juveniles were broadly distributed in low densities to a point 2.5 miles above the confluence with the mainstem. Steelhead were also present in low densities in the tributary and concentrated near the midpoint of the survey.

Little Nestucca
The entire Little Nestucca subbasin exhibited an expanded estimate of 30,555 summer rearing Coho Parr. Coho were distributed throughout 25.8 miles of mainstem and tributary habitat. Louie Cr. and it’s tributaries were the most productive segments of the subbas! in. The mainstem Little Nestucca exhibits a complex fish distribution pattern that may be related to several interdependent variables (Geomorphology, temperature and summer low flow regimes).

Little Nestucca

(Table 5)
Expanded Little Nestucca Subbasin Wide Estimates of Juvenile Salmonid Production
Survey Year Coho 0+ Sthd Cut
2001 30,555 7,580 1,735 4,260

Little Nestucca Mainstem
The mainstem was rearing an expanded estimate of 6,595 summer Coho parr. This was 22 percent of the subbasin total. In addition, there were 6,720 0+ (89% of subbasin total), 1,420 1+ Steelhead (82 % of the subbasin total) and 1,910 older age class Cutthroat (45% of the subbasin total). The mainstem however, appears to have significant water quality issues that are related to channel form and flow. The portion of the main! stem above the confluence of Sourgrass Cr. never exhibits any significant gradient to the 80ft vertical falls just below the confluence of Fall Cr. This factor combined with very minor summer flows, creates a condition conducive to elevated summer temperatures, slow pool turnover rates and potentially low levels of dissolved oxygen. In addition, because the majority of the elevation change in the active channel is observed in the bedrock falls mentioned above, the water contributed from the headwaters to the anadromous rearing reach below the falls originates from a low gradient corridor also, with the potential for exhibiting similar water quality issues. This upper reach is very nutrient rich and prolific algal blooms were observed. Coho extended to the base of this definitive barrier but their rearing densities declined as the distance increased above the confluence of Sourgrass Cr. Another clue that this upper reach of the mainstem maybe water quality limited is that Stillwell Cr. exhibited a Coho distribution pattern that is often indicative of an upstream temperature dependant migration from the mainstem. Tributaries with the potential for this upstream migration become high priority for proper culvert function (passage).

Near the confluence’s of Sourgrass Cr. and Louie Cr. mainstem rearing densities were nearly 10 times the mainstem average of 0.07 fish/sq.m. These peak densities continually diminished in the mainstem for 2.3 miles below the confluence of Louie Cr. Distribution profiles did not indicate that juveniles were conducting temperature dependant upstream migrations from the mainstem into Louie or Sourgrass. The very high densities observed in Louie and it’s primary tributary Baxter Cr. may be initiating density dependant downstream migrations that are contributing significantly to seeding the mainstem Little Nestu! cca. This observation and the lack of a significant spawning peak in the mainstem, elevate the concern for the protection and enhancement of Louie Cr. and Baxter Cr.
There was also an increase in rearing density observed in the mainstem below the confluence of Bear Cr. This may be related to contributions of juveniles from spawning activity occurring in Bear Cr. or from improvements in the mainstem summer temperature profile from the contribution of Bear. No temperature data was collected and this is an unverified observation. To strengthen the assertion that elevated mainstem temperatures exist, temperature dependant upstream migrations of Coho were observed in both Squaw Cr. and Kellow Cr. (1.5 and 1.7 miles below the confluence of Bear Cr.).
There were Chinook juveniles observed rearing in the first 6.0 miles of the mainstem in low densities. They were most abundant from the head of tide to a point 3.5 miles upstream. The total! expanded estimate of Chinook was nearly insignificant at 575. The majority of the Chinook rearing at the date of this inventory was most likely occurring in the Little Nestucca estuary.

Austin Cr.
Austin was a significant producer of Coho parr during 2001. Distribution extended to a point 0.8 miles above the confluence with the mainstem Little Nestucca and there was evidence of multiple spawning pairs. The expanded estimate of summer rearing Coho parr was 2,350 (8 % of the 5th field total). The average rearing density was 0.44 fish/sq.meter and the peak was 1.58 fish/sq.m. Austin did not exhibit the temperature dependant upstream migrations from the mainstem that adjacent tributaries did (Squaw and Kellow). This could be explained by a couple of factors, there was a series of full spanning beaver dam complexes above sample unit 2 in the inventory. The first in the series was 5 ft high and a definitive barrier to upstream juvenile movement. In addition, these beaver ponds exhibited elevated temperatures and Austin at the confluence of the Little Nestucca may not have been significantly cooler. There were significant numbers of Coho observed in Trib A of Austin up to 962 ft above the confluence with Austin Cr. There did not appear to be a spawning event in Trib A and all of the juveniles were the result of upstream temperature dependant migrations from mainstem Austin. This was also the case with West Austin Cr., no spawners and only a minor abundance of upstream migrants were observed in the first 200 ft.. Austin Cr. exhibited the highest standing crop of Steelhead juveniles in the Little Nestucca (excluding the mainstem) with an expanded estimate of 285 (16% of 5th field total). This estimate does not adequately represent the actual rearing number of Steelhead because only pool habitats were inventoried and only a small portion! of West Austin was surveyed because of the lack of Coho.

Bower Cr.
Bower enters the tidally influenced portion of the mainstem from the south. The start point of the survey was initiated above the actual confluence of the mainstem due to visibility restrictions and a lack of pool habitat in the trenched agricultural segment. Coho were distributed to a point 0.84 miles above the start point (see USGS quads). All culverts were assessed as passable for adults and juveniles. The expanded estimate of summer rearing Coho parr was 230 (<1% of 5th field total). The average rearing density was 0.19 fish/sq.m and the max was 0.43 fish/sq.m. There is a distinct pattern of decreasing densities above the start point that may be indicating a response to some unknown physical variable (see RBA cd). This pattern could be a response to the lack of pool habitat in the trenched agricultural portion or an indicator of a temperature gradient between the agricultural and forested canopy segments. Additional temperature information would be important in verifying a relationship.

Conklin Cr.
This tributary was a minor contributor of Coho production with an expanded summer parr estimate of 170. The average rearing density however within their 900 ft of distribution was nearly seeded to capacity with an average of 1.30 fish/sq.m (1.67 fish/sq.m maximum). This tributary appears to have been the destination of at least a single spawning pair. The tributary enters the upper Little Nestucca just below the falls and the end point of Coho distribution. Summer water quality is far superior to that observed in the adjacent upper mainstem.

Fall Cr.
Fall Cr. joins the mainstem Little Nestucca not far above the head of tidal influence. The stream contained multiple spawning pairs of Coho and the expanded estimate of summer rearing parr was 905 (3% of the 5th field total). The average rearing density was 0.24 fish/sq.m. and the peak density was 0.65 fish/sq.m.. There were no indicators in the distribution data of a temperature dependant upstream migration from the mainstem. Coho distribution extended 1.7 miles upstream from the confluence with the mainstem. There were Steelhead present in low densities throughout the observed distribution of Coho.

Kellow Cr.
Kellow contained an expanded Coho estimate of 40. The average rearing density was 0.2 fish/sq.m and the peak density was 0.36 fish/sq.m. Distribution extended only 828 ft and all of the Coho present were the result of a temperature dependant upstream migration from the mainstem. No spawning peak was observed.

Louie Cr.
Louie Cr. and Baxter Cr. (it’s primary tributary) can be classified as the most productive subbasins in the Little Nestucca 5th field for Coho and Cutthroat. The expanded estimate of summer rearing parr was 10,830 (35% of the 5th fields total Coho production). In addition, it appears that many of the Coho juveniles rearing in the mainstem Little Nestucca originate from density dependant downstream migrations from Louie Cr. This tributary contained 3.5 miles of Coho distribution (1.3 Louie, 1.7 Baxter and 0.5 Baxter Trib A.). The densities in Louie Cr. averaged 1.02 fish/sq.m and the peak was 2.69 fish/sq.m. Densities in Louie surged below the confluence of Baxter Cr. because of downstream migrants originating in Baxter. The Coho densities observed in Baxter were higher than the Bio-Surveys crew has ever observed in any stream corridor in the Midcoast district in the last 5 years. The average density was 2.73 fish/sq.m with a peak density of 8.3 fish/sq.m. The Coho in Baxter were distinctly smaller than observed in other reaches. Louie and Baxter appear to be very important anchor habitats within the Little Nestucca 5th field and extensive effort would be recommended for the protection and enhancement of these corridors. This pair of streams would rank as the highest priority 6th field in the Little Nestucca subbasin from the perspective of current salmonid production. The abundance and distribution of Cutthroat was also exceptional in Louie and Baxter with an expanded estimate of 860 (20% of the 5th field total). This observed level of production for Cutthroat was the highest tributary contribution.

SF Little Nestucca
The SF extended 2.8 miles to a definitive anadromous barrier (20ft vertical bedrock falls). Coho distribution terminated approximately 15 consecutive pools below the falls and Steelhead and Cutthroat were observed in low densities to the base of the falls. The expanded summer rearing Coho estimate was 4,740 (16% of the 5th field total). The average rearing density was 0.28 fish/sq.m and the peak density was 0.83 fish/sq.m.. There were 3 tributaries that also contained Coho (Kautz, Trib A, Trib B). Trib B contains a perched culvert (1ft drop) at the end of Coho distribution. The culvert is collapsing and currently a definitive barrier for upstream juvenile migrations. The distribution pattern indicates that most likely spawning occurred in the tributary below the culvert. This may also indicate that the culvert was not passable to adults (subsequent years of survey will clarify this condition).

Sourgrass Cr.
Sourgrass had an extensive lineal distribution of Coho which extended to a point 2.8 miles above it’s confluence with the mainstem Little Nestucca. This tributary corridor is paralleled closely by the main Highway which both confines the active channel and contributes negatively to it’s water quality. There was a significant accumulation of garbage and road debris in the stream corridor. Several sites have been used historically for public dumping. There was also a culvert at approximately RM 0.54 with a 3 ft perch. Distribution graphics suggest that this culvert has not impacted large anadromous migrants and no temperature dependent upstream migration pattern was noted. However, this culvert is a definitive barrier to upstream juvenile migrants and a survey conducted later in the summer may have resulted in a different conclusion for the occurrence of an upstream migration. To complicate the distribution of salmonids there is another culvert at RM 2.0 that has rusted through the bottom near the top end of the pipe. Distribution graphics suggest that there may be a passage problem developing. Some adult Coho did successfully negotiate this culvert but distinctly higher juvenile densities below the crossing suggest that low water passage for adults may be hindered. The pipe is under an extensive road fill and the pipe length may be as much of a factor as it’s condition. Additional evaluations of the current condition will be necessary to establish a higher level of confidence in actual fish response.

In general, Sourgrass Cr. is a significant producer of juvenile salmonids. The total expanded estimate of summer rearing Coho parr was 3,665 (12% of the 5th field total). The average rearing density was 0.68 fish/sq.m and the peak was 3.0 fish/ sq.m. Low densities of Steelhead were also present and Cutthroat were broadly distributed at significant rearing densities.

Stillwell Cr.
Stillwell is a significant cold water tributary in the headwaters of the Little Nestucca. Coho were distributed to a point 0.39 miles above it’s confluence. At the end of both Steelhead and Coho distribution is a failing culvert that is a definitive block for large adult salmonids (this is the second culvert in the subbasin). The pipe is old and exhibiting significant rust, it is partially collapsed and there is a wood jam at the top end of the pipe that is blocking migrants and could eventually cause a culvert failure. Maintenance is highly recommended. In addition, there is some indication that the aquatic corridor is utilized by juveniles for temperature refuge from the mainstem of the Little Nestucca. The expanded estimate for juvenile Coho was only 395 (1% of the 5th field total). The average rearing density within their truncated distribution was 0.53 fish/sq.m with a peak of 1.29 fish/sq.meter. Steelhead were present and were probably upstream migrants from the mainstem.

Trib A & B
Tributaries A and B enter the mainstem Little Nestucca from the north and within tidal influence. They both contained low densities of Coho Juveniles. The distribution in Tributary A was minor and extended only 242 ft above tidal influence. The distribution in Tributary B was more significant and extended to a point 1,503 ft above tidal influence. The distribution in Trib A was definitively the result of upstream juvenile migration. The distribution in Trib B was probably the same type of upstream migration but additional years of evaluation will be necessary to verify this assessment. The total expanded summer rearing estimate for Coho was 70 for both tributaries combined.

Other Surveyed Tributaries
There were several significant tributaries that did not contain any Coho juveniles. These were Cedar, Hiak, Judson and Upton. The first two contained Steelhead juveniles. All of these tributaries contained Cutthroat. The production potential in! each of these tributaries for Coho is limited by the availability of habitat.

Neskowin

(Table 6)
Expanded Neskowin (5th field) Estimates of Juvenile Salmonid Production
Survey Year Coho 0+ Sthd Cut
2001 7,805 7,020 930 2,870

Neskowin Cr. (mainstem)
The entire expanded minimum estimate of summer rearing Coho parr for the Neskowin basin was 7,805. The mainstem was responsible for producing 70% of that total or 5,460 juveniles. The average rearing density for Coho was 0.15 fish/sq.m and the peak was 1.28 fish/sq.m. Coho distribution continued 6.5 miles above tidal influence to a definitive anadromous barrier (7ft vertical bedrock falls) 150 ft below a major tributary confluence. The primary spawning and rearing activity was concentrated between RM 3.7 and 5.6. This was the 2 mile zone be! ginning at the confluence of Jim Cr. and extending upstream. Surveyor notes suggest that tremendous potential for both spawning and rearing exist in the lower mainstem and that the basin appears to be primarily limited by low adult escapement. In addition, Coho avoidance behavior was detected in the lower mainstem that indicates significant avian predation is occurring in this reach. This lower section could benefit from the addition of wood complexity for summer hiding cover. Steelhead were observed in the mainstem and Lewis Cr. and Hawk Cr. only. The only area observed with potential temperature gradient issues effecting the distribution of Coho was Butte Cr. The only reach within the Neskowin basin that could be classified as exhibiting a seeded condition was Trib F, a minor tributary near the headwaters with limited production potential because of it’s size.

Hawk Cr.
Hawk is a tributary of Neskowin Cr. that enters the mainstem west of Hwy 101. Both Hawk and it’s major tributary Butte Cr. contained Coho and combined produced 17 percent of the summer standing crop of Coho in the basin. In addition, Steelhead were present in Hawk but not in Butte. Hawk Cr. crosses Hwy 101 and runs through the private golf course at Hawk Creek. A large portion of it’s lineal distance lacks any riparian vegetation and there are water diversions associated with this use. The stream channel was dominated by shallow riffles and channel manipulation has eliminated most sinuosity. The stream contained Coho for 0.9 miles to the full extent of suitable habitat. The average rearing density for Coho was 0.27 fish/sq.m and the peak was 0.55 fish/sq.m. The expanded minimum estimate of Coho parr for Hawk was 805, an additional 465 Coho were present in Butte. This level of production was 16% of the 5th field total of summer rearing Coho juveniles. Butte Cr. contained Coho for 0.64 miles at an average rearing density of 0.42 fish/sq.m. The peak density was 0.83 fish/sq.m. There was a distinct and significant decline in Coho rearing density in the portion of Butte from it’s confluence with Hawk to the Hwy 101 culvert. The densities increased radically above the culvert in a pattern that suggests upstream movement was occurring from the segment of stream corridor that traverses the golf course on the west side of Hwy 101. The culvert was approximately 100 ft. long and has sagged significantly near it’s center. This low spot has filled with sediment to _ it’s potential volume. Coho were accumulating above the culvert at densities greater than observed below. This pattern may be indicative of a temperature gradient. The twin tide gates near the mouth of Butte may also be related to this unusual distribution. Cause and effect has not been verified with temperature monitoring.

Jim Cr.
Jim Cr. was a significant contributor of flow to the mainstem during summer flow regimes. The subbasin exhibited extensive sediment loading and the source was not identified within the 0.7 miles included in this inventory. There were Coho present which appeared to be the result of poor survival from a spawning event with the expanded estimate of only 55 Coho. This value comprising less than 1% of the Neskowin Basin total. The average rearing density for Coho was 0.33 fish/sq.m and the peak was 0.9 fish/sq.m. No Steelhead were present.

Lewis Cr.
Lewis was another major contributor of summer flow. The abundance of Coho was significant with an expanded estimate of 375 juveniles. There was a spawning peak identified at approximately 2,500 ft. and the distribution graphics suggest another peak within a few hundred ft. of the mouth. This level of production represents approximately 5% of the Neskowin basin total. The average rearing density for Coho was 0.53 fish/sq.m and the peak was 1.5 fish/sq.m. Steelhead were also present in the subbasin and juvenile salmonid production appeared to be limited primarily by a lack of adult escapement.

Fall Cr.
Fall Cr. enters from the south through a 380 ft long culvert under Hwy 101. The culvert appears to be passable with Coho spawning and rearing occurring above. There is a 4ft drop into a plunge pool below the culvert that is a definitive barrier for the upstream migration of juveniles. There was however, no indication that juveniles were attempting to utilize Fall Cr. for temperature refuge. The total expanded estimate for summer rearing Coho parr was 140 or 2% of the total production for the Neskowin basin. The average rearing density was 0.13 fish/sq.m and the peak was 0.34 fish/sq.m. The! re were no Steelhead present.

Prospect Cr.
Prospect contributes significant summer flow to the mainstem Neskowin. The aquatic corridor exhibited steeper gradients and larger substrates than adjacent tributaries (Jim, Lewis). There were low densities of Coho observed with the expanded estimate totaling 40 juveniles (<1% of Neskowin basin total). The average rearing density for Coho was 0.13 fish/sq.m and the peak was 0.24 fish/sq.m. No Steelhead were present.

Sloan Cr.
Sloan was a minor contributor of summer flow to the mainstem with salmonid production limited by habitat size. The best aquatic habitat existed in the lower end, which exhibited larger pool surface areas. Coho were present with an expanded estimate of Coho production at 110 (1% of Neskowin Basin total). The average rearing density for Coho was 0.52 fish/sq.m and the peak was 1.1 fish/sq.m. No Steelhead were present.

Kingston Cr.
Kingston enters the mainstem Neskowin over a 6 ft falls. Summer flow is minor and habitat size and access is limiting salmonid production. No Coho or Steelhead were observed.

Trib F
This Tributary is a minor contributor of summer flow and Coho distribution extended 1100 ft from the mainstem. The average rearing density was 1.85 fish/sq.meter and the peak was 2.69 fish/sq.m. This represents a condition that could be classified as seeded to capacity within their distribution. The production potential is minor with an expanded estimate for the Trib of 105 Coho. No Steelhead were present.

Trib G
This tributary enters on the left through a campground and contained an expanded Coho estimate of 130. The average rearing density for Coho was 0.43 fish/sq.m and the peak was 0.83 fish/sq.m.  No Steelhead were present.

Sand Lake

Surveys conducted in the Sand Lake basin assessed the condition of 10.2 miles of available habitat. An additional 1.9 miles of potential habitat (16 % of the lineal total) was not surveyed due to poor visibility from tannins and / or sediment. The unsurveyed portions exist in lower Trib A of Sand Cr. and a no name Trib of Sand Cr. entering on the right above the confluence of Andy Cr.. Refer to the USGS quads included as a product of this inventory to identify the start point of Trib A.. The Sand Lake Estuary contains a single primary source of potential salmonid habitat, Sand Cr.. Sand Cr. is a 4th order stream with several significant tributaries, Jewell, Andy, Davis and Trib A.. In addition, the estuary receives extremely high quality fresh water input from three 2nd order streams that enter on the! southern end of the bay, Gurtis, Reneke and Beltz.

(Table 7)
Expanded Sand Lake (5th field) Estimates of Juvenile Salmonid Production Survey Year Coho 0+ Sthd Cut
2001 2,940 2,345 155 1,335

Sand Cr.
Both Coho and Steelhead were observed within the mainstem of Sand Cr. The expanded abundance of summer rearing Coho for all of Sand Cr. and it’s tributaries was 2,940. This represents at least a minimum number present. Additional production is likely present in the 16 % of the lineal habitat uninventoried. The presence of these Coho is significant since the SRS adult inventory for the year 2001 observed 0 Coho in the basin. Coho distribution extended up mainstem Sand Cr. 3.3 miles above the head of tidal influence. The primary spawning activity was observed between RM 1.5 and 3.3. The average rearing density for Coho was 0.12 fish/sq.m of pool surface area with an observed peak density of approximately 0.7 fish/sq.m. The expanded rearing estimate for Sand Cr. excluding Jewell and Andy was 1,000 (34% of the basin total). Steelhead were present in the system but much less abundant than Coho and concentrated in a much narrower band of habitat from RM 1.5-2.7. The potential for restoration is significant in mainstem Sand with visible impacts from upslope harvest activity and agricultural use present.

Jewell Cr.
Jewell exhibited an average Coho rearing density of 0.28 fish/sq.m with a peak density of 1.4 fish/sq.m. Distribution extended 1.4 miles and an expanded estimate of abundance was 790 Coho (27% of the basin total). There were small numbers of steelhead present and excellent densities of Cutthroat (0.2 fish/sq.m avg.).

Andy Cr.
Andy Cr. contained abundant gravels that were well sorted. The average density of Coho was 0.37 fish/sq.m with a peak density of 1.1 fish/sq.m. Coho were broadly distributed and extended 1.8 miles above the confluence with Sand Cr. Andy Cr. contained an expanded estimate of 1,150 Coho (39% of the basin total). There were no Steelhead observed.

Davis Cr.
Davis was classified as exhibiting low gradient swampy habitat with very little if any potential for spawning. The substrates were silt dominated. There were only Cutthroat observed, no Coho or Steelhead present.

Trib A.
This lowest tributary of Sand Cr. was completely sand dominated with limited to no potential for spawning. There were only Cutthroat observed, no Coho or Steelhead present.

Sand Lake Southern Tributaries
Three 2nd order tributaries entering from the southern side of the estuary (Gurtis, Reneke, Beltz) exhibited significant summer flows ! that were contributing very cold water to the shallow Sand Lake estuary. All three of these tributaries originate on a north slope and emanate from well canopied headwaters. Two of the streams currently exhibit passage problems at the main hwy culvert. The 3 ft culvert on Beltz has a 3.5 ft drop to the stream channel and may pass adults but is a definitive barrier to the potential upstream temperature dependant migrations of juveniles. The 1 ft culvert on Reneke is almost entirely blocked and is probably not passable for adults or juveniles. The crossing on Gurtis is in good condition. Multiple domestic water diversions were present within the Gurtis Cr. survey. None of these tributaries contained Coho or Steelhead (even below the questionable culverts), none of them are high priority for large anadromous spawners because of the limiting size of the habitat. There is however, the potential for these three streams to be very significant players in the health and productivity of the intertidal wetlands and estuary that they contribute to. In addition, juvenile salmonids could utilize these cold water habitats for refugia in years of higher abundance.
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Recommendations

There are several conclusions based on the preceding analysis that lead us to the point of developing some general recommendations.

• The weir at the Cedar Cr. facility is problematic for wild salmonids in the Three Rivers subbasin. Retrofitting the weir at the Cedar Cr. site with a sorting facility and a Three Rivers water supply to the fish ladder could result in significant increases in wild production for at least OCN Coho than is currently achieved. Additional benefits would also be realized by wild Winter Steelhead, wild Fall Chinook and Searun Cutthroat Trout! . Phase 2 plans previously submitted to the R&E Board already outline the changes and designs necessary for the trapping and sorting at this site that would provide the discrimination required to pass or retain adults without truncating run timing and effectively denying access for certain components of every population. Re-visit the phase 2 option, clearly state the objectives and benefits to wild salmonids and review any alternate strategies that may be more cost effective solutions than previously proposed.
• The mainstem Nestucca is a very high priority for restoration and enhancement because of the observed production potential for all salmonids. This suggests that the maintenance, enhancement and preservation of water quality in the mainstem is paramount. This also suggests that a well developed monitoring strategy is essential for quantifying the inter / intra annual trends! in water quality parameters. Prioritize restoration reaches by species and continue to develop an understanding of the winter habitat needs of salmonid juveniles rearing in the mainstem (Habitat selection? Population shifts?). Distribution and Rearing

Density Graphics

For the year 2002 effort, an Excel Pivot Table has been developed that allows the user to preview distribution, density and abundance graphics by stream. In the future, with the benefit of supplemental years of data, this database will allow managers and users to access trend information for all of the basins and subbasins in the Nestucca / Neskowin management area including direct ocean tributaries. Please contact the Nestucca / Neskowin Watersheds Council for an updated version of this tool.

Clarification Letter to 2002 RBA Report

To: Nestucca / Neskowin Watersheds Council
RE: Clarification to 2002 RBA Final Report from Steve Trask

It has come to our attention that there may have been some misleading information contained in the Rapid Bio-Assessment Final Report document. Upon review of the document it is obvious that there is a need for clarification. Specifically, the summary section of the report for the Three Rivers subbasin describes an adult passage condition at the Cedar Cr. weir that may be impacting late returning components of the wild Fall Chinook and OCN Coho populations. The statement in question reads " It is this line of demarcation between Fall Chinook and Winter Steelhead (variable from year to year and dependant on flow regimes) that truncates the late spawning component of both the wild Fall Chinook ! and the late OCN Coho populations." This sentence clearly, could lead the reader to assume that there is a definitive barrier to upstream migrants imposed at the weir at a given date and that no wild passage is available after that point. The sentence should read " It is this line of demarcation between Fall Chinook and Winter Steelhead (variable from year to year and dependant on flow regimes) that may truncate the late spawning components of both the wild Fall Chinook and the late OCN Coho."

In realistic terms we know that after the weir is raised there can be multiple windows of opportunity for wild adult Chinook or Coho to pass the facility. There are high flow conditions that overpower the weir, dropping it automatically for periods of 1- 4 days. The intent of our concern for the Cedar Cr. weir was to establish that unimpeded access may not be readily available at all flow regimes for! every year. The late spawning components of these two populations can typically be very ripe and any potential delay could result in turning them away from their destination. The Rapid Bio-Assessment inventory data can only definitively describe summer juvenile distribution and estimate summer juvenile production. Many of the other uses of the data are inferential and designed only to highlight potential concerns or opportunities (problem culverts, identification of key anchor habitats, etc.) for watershed managers. The most significant observation revealed in the Three Rivers data is that all species except Coho appear to be well distributed and rearing in densities that were common in other Nestucca 5th fields for the summer of 2002. The dramatic lack of Coho in a year of significantly increased adult escapement led us to an investigation of potential passage issues. There is no adult data that leads us to conclude that OCN Coho are stagin! g below the weir. In fact, daily observation at the weir by the Cedar Cr. Hatchery staff indicate that the lack of Coho is not an anomaly but is typical of Coho escapement to the subbasin. The summary only meant to infer that if there were late returning Coho or Chinook, that they may be faced with blocked passage for an undetermined length of time (depending on flow regimes) and that this condition may negatively impact escapement to the upper subbasin.

The RBA inventories planned for the next two years will help describe and quantify each of the 3 Coho cohorts rearing in the Three Rivers subbasin and they may help clarify the current condition at the Cedar Cr. site. In the interim, understand that our intent is to utilize the data we have to quickly identify potential issues in your watersheds.

I would recommend that you provide this letter of clarification as an addendum to the final report document.
Thanks

Steve Trask / Bio-Surveys, LLC