Walker Creek Salmon Monitoring Program FINAL COMPILATION REPORT

Transcription

1 FINAL COMPILATION REPORT Submitted to: California Department of Fish and Game Fishery Restoration Grant Program Grant No. P Submitted by: Marin Municipal Water District (MMWD) 220 Nellen Avenue Corte Madera, CA In Association with: Garcia and Associates (GANDA) 1 Saunders Avenue San Anselmo, CA March 2010

2 TABLE OF CONTENTS PROJECT INFORMATION... iv 1.0 INTRODUCTION Project Background Scope of Work STUDY AREA METHODS Adult Spawner Surveys Juvenile Coho Salmon Surveys Snorkel Surveys Electrofishing Surveys Water Temperature Monitoring Benthic Macroinvertebrate Monitoring Preparation and Training Benthic Macroinvertebrate Sampling RESULTS Juvenile and Spawner Surveys Prior to Winter 2006/2007 Spawner Surveys Genetic Analysis Winter 2007/2008 Spawner Surveys Genetic Analysis Winter 2008/2009 Spawner Surveys Genetic Analysis Winter 2009/2010 Spawner Surveys Genetic Analysis Juvenile Coho Salmon Surveys Snorkel Surveys Electrofishing Surveys Genetic Analysis Juvenile Coho Salmon Surveys Snorkel Surveys Electrofishing Surveys Genetic Analysis Juvenile Coho Salmon Surveys Snorkel Surveys Electrofishing Surveys Genetic Analysis Water Temperature Data Benthic Macroinvertebrate Data i

3 5.0 CONCLUSIONS Adult Spawner Surveys Juvenile Coho Salmon Surveys Water Temperature Monitoring Benthic Macroinvertebrate Monitoring ACKNOWLEDGEMENTS REFERENCES Cover Photo: Walker Creek from Indian Grinding Rock at Walker Creek Ranch Walker Creek mainstem at McDonald Ranch ii

4 List of Figures Figure 1. Walker Creek Watershed Figure 2. Project Location Map Figure 3. Survey Reaches and Fish/Redd Observations from 2006/2007 Adult Coho Spawner Surveys Figure 4. Survey Reaches and Fish/Redd Observations from 2007/2008 Adult Coho Spawner Surveys Figure 5. Walker Creek Juvenile Coho Salmon Survey Locations and Observations Figure 6. Walker Creek Benthic Macroinvertebrate Survey Locations List of Tables Table 1. Walker Creek Coho Salmon Life History Timeline Table 2. Salmonid Plantings and Monitoring Observations Table 3. Fish observations from Walker Creek spawner surveys Table 4. Redd observations from 2006/2007 Walker Creek spawner surveys Table 5. Fish observations from 2007/2008 Walker Creek spawner surveys Table 6. Redd observations from 2007/2008 Walker Creek spawner surveys Table 7. Redd observations from 2008/2009 Walker Creek spawner surveys Table 8. Fish observations from 2009/2010 Walker Creek spawner surveys Table 9. Redd observations from 2009/2010 Walker Creek spawner surveys Table 10. Fish present in each pool where juvenile coho salmon were observed during 2007 Walker Creek snorkel surveys (August/September 2007) Table 11. Summary of data from 2007 Walker Creek electrofishing surveys (coho salmon and steelhead only) Table 12. Fish present in each pool where juvenile coho salmon were observed during 2008 Walker Creek snorkel surveys (August 2008) Table 13. Summary of data from 2008 Walker Creek electrofishing surveys (coho salmon and steelhead only) Table 14. Summary of data from fall 2007 BMI sampling in Walker Creek, conducted by staff and students at Walker Creek Ranch Table 15. Summary of data from January 2009 BMI sampling in Walker Creek, conducted by GANDA Table 16. Yearly maximum streamflow data for Walker Creek over the past 11years (USGS Gage ; source: USGS 2010) APPENDICES: Appendix A. Walker Creek Water Temperature Monitoring Summary. Appendix B. Walker Creek Aquatic Invertebrate Monitoring Reports. iii

5 PROJECT INFORMATION Grant Number P (CDFG Fishery Restoration Grant Program) Project Name Geographic Area Walker Creek Watershed (tributary to Tomales Bay) Location of Work Walker Creek and tributaries below Soulajule Reservoir, western Marin County, CA. Geospatial Reference Location Latitude Longitude (NAD27) (USGS gage near the middle of the study area at Walker Creek Ranch) Project Dates 2005 to 2010 Walker Creek mainstem iv

6 1.0 INTRODUCTION 1.1 Project Background In an attempt to reestablish a viable population of coho salmon (Oncorhynchus kisutch), the California Department of Fish and Game (CDFG) in 2003 began a multiple-year effort of planting coho salmon into Walker Creek, a tributary to Tomales Bay in western Marin County (Figure 1). Since the winter of 2003/2004, a total of 264 adult coho salmon, 3,400 coho smolts, and 500 coho fingerlings have been released into Walker Creek. Planting of these fish is the latest in a long-standing series of efforts to reestablish coho salmon in Walker Creek. The Marin Municipal Water District (MMWD) has been a partner in these efforts by conducting monitoring surveys to help evaluate the success of the program. In the early 1900 s, coho salmon were abundant in Walker Creek; however, they appear to have been extirpated by 1948 (MMWD, unpublished data). Severe erosion and landform changes associated with dominant land-use practices during the past 100 years have resulted in the dramatic decline of anadromous fishes throughout the region (Hammack 2005). For example, the creation of what is now Soulajule Reservoir by a private landholder in the 1960 s blocked all anadromous fish migration to the upper reaches of Arroyo Sausal, thereby eliminating steelhead and coho salmon from a significant portion of their historic range in the watershed. Several earlier efforts to reintroduce coho salmon into Walker Creek began in the mid- 1970s. CDFG stocked 47,079 coho yearlings between 1977 and 1980, and an additional 22,000 coho fingerlings in In 1979, Soulajule Reservoir was expanded by MMWD in order to increase municipal water storage. This reservoir expansion project established new minimum flow requirements for Walker Creek under an agreement between MMWD and CDFG. These minimum flow releases are as follows: Normal Year Dry Year Critical Dry Year Jan - Mar 20 cfs 10 cfs 0.5 cfs Apr 10 cfs 5 cfs 0.5 cfs May Dec 5 cfs 2 cfs 0.5 cfs Nov Dec(1) 20 cfs 10 cfs 0.5 cfs (1) The winter instream flow does not go into effect until there is a 25 cfs trigger flow in the creek, or Jan 1 in the absence of a trigger before then. Despite efforts to reintroduce and improve habitat conditions for coho salmon, no coho were collected during CDFG electrofishing surveys in 1993, and no coho were observed during a snorkel survey conducted by the National Marine Fisheries Service (NMFS) in Therefore, in 2001, CDFG began a coho hatchery-rearing program. Juvenile coho salmon were collected from nearby Olema Creek, in the Lagunitas Creek watershed, and raised at either the Warm Springs Hatchery or the Bodega Marine Laboratory. These fish of Olema Creek origin have been the source of all Walker Creek coho salmon releases since A total of 80 adults were released into Walker Creek in the 1

7 winter of 2003/2004; 87 adults were released in the winter of 2004/2005; 40 adults were released in the winter of 2005/2006; 3,400 smolts were released in June 2007; 57 adults were released in January 2008; and 500 fingerlings were released in November 2008 (pers. comm. M. Kittel, CDFG). The plantings are summarized below: Season/Year Number Life Stage Winter 2003/04 80 Adults Winter 2004/05 87 Adults Winter 2005/06 40 Adults June ,400 Smolts January Adults November Fingerlings The life history of the coho in the Walker Creek program can be traced as shown in Table Scope of Work A grant awarded to MMWD through CDFG s Fishery Restoration Grant Program (Grant # PO530414) has allowed the expansion of coho monitoring efforts in Walker Creek in order to evaluate the success of the stocking effort over a five-year period between 2005 and As part of the, MMWD contracted with Garcia and Associates (GANDA) to conduct adult and juvenile coho salmon surveys between 2006 and 2008 in order to determine: If adult coho salmon are spawning in Walker Creek, If a population of juvenile coho salmon is present in Walker Creek, and if these juveniles are offspring of the planted coho or part of a naturally occurring population, and If there are adult coho salmon returning to Walker Creek; and if these adults are offspring of the planted coho or part of a naturally occurring population. MMWD conducted surveys prior to 2006, then in association with GANDA between 2006 and 2008, and then MMWD continued the surveys in 2009 and A secondary benefit from the salmon monitoring program is the acquisition of additional information regarding the steelhead (Oncorhynchus mykiss) population in Walker Creek, and possibly incidental information on other potentially occurring salmonids (e.g., Chinook salmon [Oncorhynchus tshawytscha]). Additionally, the program funded benthic macroinvertebrate (BMI) monitoring in Walker Creek conducted in collaboration with students and staff at Walker Creek Ranch (owned and operated by the Marin County Office of Education) in 2007 and by GANDA in January BMI monitoring was initiated in order to help assess ambient biological conditions in Walker Creek, evaluate the availability of food resources for salmonids, provide baseline data for future monitoring efforts, and expose students and staff at Walker Creek Ranch to the concepts and practices of biological monitoring for educational purposes. A water 2

8 temperature monitoring effort was also conducted by monitoring temperatures at eight sites in between April 2007 and January This compilation report describes the results from the four study elements of the Walker Creek Salmon Monitoring Program: adult spawner surveys and juvenile coho salmon surveys conducted between 2003 and 2010; BMI monitoring conducted during 2007 and 2009; and water temperature monitoring in 2007/08. Recently released adult coho salmon observed during a spawner survey in mainstem Walker Creek 3

9 2.0 STUDY AREA The study area for the (Figure 2) included the upper portion of the Walker Creek watershed accessible to salmon, primarily between Soulajule Reservoir and Walker Creek Ranch. Surveyed tributaries included Arroyo Sausal, Salmon Creek, Verde Canyon Creek, Frink Canyon Creek, and Chileno Creek. The extent of the survey areas for the different study elements was largely determined by landowner cooperation and access. The study area for adult spawner surveys was divided into four to five study reaches (as illustrated in Figures 3 and 4): Reach A included Arroyo Sausal from Soulajule Reservoir downstream to the Salmon Creek confluence (note that approximately 300 meters of this reach immediately upstream of the confluence with Salmon Creek was consistently too deep and brush-choked to survey); Reach B included Walker Creek from the confluence with Salmon Creek downstream to Marshall-Petaluma Road, as well as approximately one mile of Salmon Creek immediately upstream of the Walker Creek confluence; Reach C included Walker Creek from Marshall-Petaluma Road downstream to the lower extent of the Walker Creek Ranch property (owned by the Marin County Office of Education); Reach D included Walker Creek from the bottom of Walker Creek Ranch downstream to the confluence with Chileno Creek; and A fifth survey reach, the lowermost portion of Chileno Creek, immediately upstream of the Walker Creek confluence, was also surveyed once to assess available spawning habitat. The study area for juvenile coho salmon surveys (Figure 5) included approximately six miles of Walker Creek, from the outfall of Soulajule Reservoir to the downstream extent of the Walker Creek Ranch property at the Zwart bridge. Salmon Creek, Verde Canyon Creek, and Frink Canyon Creek were also surveyed in this reach. Overall, the study area for juvenile surveys included a total of approximately eight stream miles, as follows: Walker Creek from Soulajule Reservoir downstream for approximately 6 miles; Frink Canyon Creek from the Walker Creek confluence upstream approximately 0.25 mile; Verde Canyon Creek from the Walker Creek confluence upstream approximately 0.75 mile; and Salmon Creek from the Walker Creek confluence upstream approximately 1 mile. 4

10 Water temperature monitoring was conducted at eight monitoring sites between Soulajule Reservoir and the mouth of Walker Creek, including sites in Salmon Creek and Chileno Creek, and a site in the mainstem of Walker Creek just upstream from Highway 1 (see Appendix A) Benthic macroinvertebrate sampling occurred at two locations in Walker Creek on the Walker Creek Ranch property (see Figure 6 and Appendix B). These two locations are referred to as Sandy Flats and Alder Flats by the Walker Creek Ranch staff. Walker Creek viewed from the Petaluma-Marshall Road Bridge 5

11 3.0 METHODS 3.1 Adult Spawner Surveys Spawner surveys were conducted infrequently during the 2003/04, 2004/05, and 2005/06 spawning seasons. Then the surveys were conducted approximately bi-weekly during the 2006/2007, 2007/2008, 2008/2009, and 2009/2010 spawning seasons; weather and flows permitting. During each survey, teams of biologists walked upstream through each reach looking for adult fish and any evidence of spawning. Teams were comprised of a combination of MMWD and GANDA staff. Crews recorded all observations of live fish, carcasses, and redds. Each recorded observation was assigned a record number describing the type of observation, stream reach, and date of survey. All live fish were identified to species and the certainty of each identification was recorded as either: 1) sure, 2) maybe one species or another, or 3) unknown. Fork length (FL) and sex of each fish was also recorded (with the certainty of gender identifications ranked as above), where possible. For live fish observations, fork lengths were estimated visually. Any tags, clips, brands, or other identifying marks were also noted. If an individual fish was observed on or near a redd, the redd number was recorded (see tables below) on the fish data sheet. Locations of all fish observations were recorded on reach maps and/or handheld GPS units. Carcasses were described as above, and assigned a carcass tag (coho carcasses only). Tissue samples were collected from the dorsal fin and operculum of each coho carcass and sent to the genetics lab at the National Oceanic and Atmospheric Administration (NOAA) National Marine Fisheries Service Southwest Fisheries Science Center in Santa Cruz for genetic analysis. For each newly encountered carcass, the tail was severed at the caudal peduncle in order to designate that carcass as having been previously documented (i.e., so that it could not be mistaken as a new carcass during subsequent surveys). Carcass locations were also recorded using GPS and marked on the reach map. All observed redds were visually identified to species when possible. For each redd, the dimensions of the pit (length, width, and depth) and the tail spill (length and two widths) were recorded. During each survey, any redds documented were new since any prior survey (i.e., age 1 per the CDFG criteria). Redd locations were flagged with the date, redd number, species (coho or steelhead), redd dimensions, and redd position (e.g., mid-channel, left or right bank) marked on the flagging. Redd locations were also recorded using GPS and marked on the reach maps. If a live fish was observed on or near a redd, the fish record number was noted on the redd data sheet. Any redds with fish present on them were noted and left to be measured at a later date so as not to disturb spawning activities. Water and air temperature were measured at the beginning of each spawner survey. Weather conditions and water clarity and visibility were also described. Stream 6

12 discharge information was collected from USGS gage located in Reach C of the study area, at Walker Creek Ranch (USGS 2010). 3.2 Juvenile Coho Salmon Surveys Surveys for juvenile coho salmon were initially performed by MMWD staff in 2004 and 2005 as snorkel surveys only. Later, they were performed by GANDA using a combination of snorkeling and qualitative one-pass electrofishing techniques during 2006, 2007, and Snorkel Surveys During snorkel surveys, two GANDA biologists walked the entire 8-mile survey area (described above) and snorkeled all pools 1.5 feet deep or deeper, working in the upstream direction. All juvenile coho salmon observed were enumerated, estimated to total length (TL), and the pool location was recorded using a handheld GPS unit. In each pool where coho were observed, all fish were identified to species and enumerated. Snorkel surveys were conducted in October 2006, August/September 2007, and August Electrofishing Surveys Qualitative one-pass electrofishing surveys were also conducted to supplement snorkelsurvey data and allow collection of tissue samples from juvenile coho salmon for genetic analysis. Two days of electrofishing were conducted each year between 2006 and In October 2006, three sections of Walker Creek and the lower portion of Verde Canyon Creek were surveyed (i.e., electrofishing survey areas 1, 3, 4, and 5 in Figure 5). In September and October 2007, three sections of Walker Creek and the lower portions of Frink Canyon Creek and Salmon Creeks were surveyed (i.e., electrofishing survey areas 1, 2, 3, 6, and 7 in Figure 5). In 2008, two sections of Walker Creek were surveyed. During each survey, a team of biologists (1-2 backpack electrofishers and 2-3 netters) comprised of a combination of GANDA and MMWD staff fished the selected reach from downstream to upstream end, capturing as many fish as possible during a single pass. All collected fish were identified to species; coho salmon and steelhead specimens were enumerated and measured to the nearest mm FL. Fin clips were collected from all coho specimens for genetic analysis. All fin clips were sent to the NOAA genetics lab in Santa Cruz for analysis. 3.3 Water Temperature Monitoring A total of eight temperature data loggers were installed at locations in the mainstem of Walker Creek and two of its tributaries in April, 2007 (see Appendix A). The data loggers recorded water temperature hourly. Five of the eight temperature data loggers were retrieved in January, 2008, the logger at Site 8 was retrieved in February, 2008, and the loggers at Sites 6 and 7 were retrieved in December, 2008 (but only contained 7

13 data into March, 2008). Five of the date loggers were located in mainstem Walker Creek, at Sites 1, 3, 5, 6, and 8. The remaining three data loggers were placed in the tributary streams of Salmon Creek (Site 2), Frink Canyon (Site 4) and Chileno Creek (Site 7). The mainstem data logger at Site 5 was located immediately downstream from the mouth of Frink Canyon and the mainstem data logger at Site 6 was located immediately upstream from the mouth of Chileno Creek. 3.4 Benthic Macroinvertebrate Monitoring In 2007, GANDA developed and helped implement an aquatic benthic macroinvertebrate (BMI) monitoring program to be performed on the Walker Creek Ranch portion of Walker Creek. The objective of this program was to design a sampling protocol and train the staff at Walker Creek Ranch to lead a simple, aquatic macroinvertebrate sampling and identification module as part of their current educational program. This program was intended to expose students to the concept of biomonitoring and to build a database that could be used to monitor trends in the macroinvertebrate community in Walker Creek. As part of the BMI monitoring program, GANDA developed a stream-specific macroinvertebrate key, provided training in BMI collection and sample processing techniques (including sorting and taxonomic identification), and summarized the data collected during the fall of GANDA conducted an additional sampling effort in January 2009 to establish a more rigorous taxonomic baseline. The methods for the benthic macroinvertebrate monitoring are detailed in Appendix B Preparation and Training Based on preliminary BMI sampling performed in May 2007, GANDA developed a student-friendly key for identification of BMI samples tailored to the benthic fauna of Walker Creek. This key contained pictures, descriptions, and names of all the locally common taxa and was developed to allow teachers and students to identify and enumerate organisms found in benthic samples they collected in Walker Creek to at least the order level (and, if desired, the family level). An easy-to-follow field sampling protocol and equipment checklist was also developed to help simplify and standardize the sampling efforts. Data sheets were created to allow for the easy recording of BMI and water quality data collected. These materials were used by the staff to teach students and youth groups that visit Walker Creek Ranch about biological monitoring concepts and to lead the BMI sampling and identification efforts. GANDA also conducted a field-training workshop for the staff at the Walker Creek Ranch. This training workshop included an introduction to the prepared materials and the BMI sampling equipment, a lecture on rapid bioassessment and aquatic macroinvertebrate sampling and processing techniques, a discussion on data sheet submittal procedures, and a field demonstration of the sampling and identification procedures. The program staff was given adequate time to ask questions and become familiar with the procedures so that they could lead the sampling events in the future. 8

14 3.4.2 Benthic Macroinvertebrate Sampling Benthic macroinvertebrate sampling was conducted by students, youth groups, and Walker Creek Ranch staff. A total of four BMI sampling events were conducted at two survey locations. The Alder Flats location was sampled on October 2 nd and November 15 th, 2007, and the Sandy Flats location was sampled on November 8 th, and November 29 th, During each sampling event, students and instructors assisted in the collection of several kick samples. Kick samples were collected using a D-framed net or kick seine. For each sample, invertebrates were collected from a one-square-foot area of the streambed (located immediately in front of the net). This area was disturbed and agitated by hand so that invertebrates would drift into the net. Larger rocks were scrubbed by hand in front of the net so that any dislodged invertebrates were collected in the net. BMI samples were sorted on-site by placing the sample material into white enamel trays and removing organisms with tweezers (or by hand). Organisms were sorted and grouped into different compartments of ice cube trays, then identified using the taxonomic key provided. The counts and sizes of each type of BMI collected were recorded on the provided datasheets, along with site conditions and water quality information from each sampling event. GANDA conducted an in-depth sampling effort following the SWAMP protocol (SWAMP 2007) on January 21 st, This effort consisted of collecting a Targeted Riffle Sample and a Multi-habitat sample at both the Alder Flat and Sandy Flat locations. Juvenile coho collected from Walker Creek to get a fin clip for genetic analysis 9

15 4.0 RESULTS A summary of coho and steelhead observations from all survey conducted between 2004 and 2010 is presented in Table 2. The first survey conducted under the CDFG grant-funded phase of the program was the 2006 juvenile surveys. f. Surveys under that funding continued through the 2008 juvenile survey. Prior to 2006, and after 2008, the surveys were conducted by MMWD staff. Below, we provide a brief summary of the survey results prior to 2006 and then we review each survey in more detail, between 2006 and The data sheets and field notes are provided in our individual survey reports (Aramayo and Chan 2007a, 2007b, 2008a, 2008b, 2009; Lessard 2008; GANDA 2009). 4.1 Juvenile and Spawner Surveys Prior to 2006 Spawner surveys conducted during the 2003/04 spawner season, after the first release of adult coho, identified two coho redds. These redds were presumed to have been created by the planted adult coho. We also identified 11 adult steelhead and 11 steelhead redds during these surveys. Snorkel surveys for juvenile coho conducted in 2004 identified 65 juvenile coho. These juveniles were presumed to be the offspring of the 2003/04 planted adults. Most of the coho were observed in Salmon Creek, where 52 juveniles were observed, and they may have all been from a single coho redd. The remaining 13 juvenile coho were scattered through the mainstem of Walker Creek. Numerous juvenile steelhead were also observed but were not counted. The spawner surveys conducted during the 2004/05 spawning season observed 3 adult coho and 4 coho redds. As with the previous year, these redds were presumed to have been created by the adult coho that had been planted that season, in early December. We also identified one steelhead redd. Snorkel surveys during the summer of 2005 observed 176 juvenile coho. These juveniles were presumed to be offspring of 2004/05 planted adults. This was an exciting result not only because of the large number of juvenile coho but also because we observed 85 scattered through the mainstem Walker Creek, as well as 91 juveniles in Salmon Creek. This revealed successful spawning and rearing from more than just one redd. The 2005/06 spawner surveys were conducted following the planting of adult coho in late November We only observed 2 adult coho that year, both presumed to be from the planted adults. We did not observe any coho redds nor did we observe any adult steelhead or steelhead redds. We observe two diggings but these were not fully developed redds. The 2005/06 season ended abruptly with the severe flooding that occurred during the storm on New Years Eve and we were not able to conduct any coho surveys after that. 10

16 4.2 Winter 2006/2007 Spawner Surveys A total of four adult coho salmon (2 live fish and 2 carcasses) and seven coho redds were observed in Walker Creek during the 2006/2007 spawner surveys. The significance of these findings is that these returning adults were likely the offspring of the first planting of adults during the 2003/04 season (see Tables 1 & 2) Adult coho salmon ranged in size from 41 to 56 cm FL. Both coho carcasses were jack males (i.e., 2-year-old precocious 1 males). In addition, 11 adult steelhead (all live fish, no carcasses), one unknown salmonid, and 19 steelhead redds were observed during our surveys. Adult steelhead ranged in size from cm FL. Eight redds of uncertain origin (i.e., either coho or steelhead) were also observed, along with one lamprey carcass (Lampetra sp.). Fish observations from 2006/2007 spawner surveys are summarized in Table 3. The location of these observations within each survey reach is illustrated in Figure 3. Coho redds observed during the 2006/2007 spawning season averaged 3.1 meters total length (pit + tail spill), 2.3 meters total width (maximum width), and 0.18 meters in depth. Steelhead redds were smaller and deeper on average (1.3 meters total length, 1.0 meters total width, and 0.23 meter depth). Redd observations are summarized in Table 4. The location of these observations within each survey reach is also illustrated in Figure 3. Water temperatures in Walker Creek ranged from 6.0 to 13.0 C during the 2006/2007 spawner surveys and air temperatures ranged from 4.0 to 12.5 C. Discharge ranged from 6 to 31 cfs in mainstem Walker Creek during our surveys (although flows were much higher on other days during the 2006/2007 spawning season). Visibility ranged from 0.2 to 1.2 meters during our surveys (i.e., from poor to excellent water clarity). Reach A (Soulajule Reservoir downstream to Salmon Creek confluence) Reach A was surveyed five times during the 2006/2007 spawning season (November 28th, December 15 th, January 3 rd, January 19 th, and January 30 th ). No live adult coho salmon, carcasses, or redds were observed in Reach A. The only recorded observation from this reach was one adult steelhead (undetermined sex, 56 cm FL) seen immediately upstream of the bridge. No steelhead carcasses or redds were observed in this reach. Reach B (Salmon Creek confluence to Marshall-Petaluma Road, plus one mile of Salmon Creek) Reach B was surveyed five times during the 2006/2007 spawning season (November 28th, December 15 th, January 3 rd, and January 19 th, and January 30 th ). One adult 1 Precocious, in this sense, refers to males that return to spawn early as two year olds rather than as typical three year olds. 11

17 female coho salmon (56 cm FL) was seen holding on a redd in this reach on January 3 rd. One jack male coho carcass (41 cm FL) was also observed on January 3 rd. A pair of adult steelhead (one male 53 cm FL, and one female 53 cm FL) were observed holding on a redd in this reach on January 3 rd and a single unknown small salmonid (approximately 25 cm FL) was observed near another redd on January 3 rd. A total of two coho redds, five steelhead redds, and one redd of unknown origin were observed in Reach B (see dates for redd observations in Table 4). Reach C (Marshall-Petaluma Road to bottom of Walker Creek Ranch) Reach C was surveyed five times during the 2006/2007 spawning season (November 28th, December 15 th, January 3 rd, January 19 th, and January 30 th ). No adult coho salmon (live fish or carcasses) were observed in this reach during our surveys. One live adult steelhead (undetermined sex and length) and one lamprey carcass were observed on January 19 th. A total of two coho redds, three steelhead redds, and two redds of unknown origin were observed in Reach C (see dates for redd observations in Table 4). Reach D (bottom of Walker Creek Ranch to Chileno Creek confluence) Reach D was only surveyed twice during the 2006/2007 spawning season (January 9 th and January 30 th ). Two adult coho salmon were observed on January 9 th, one female (undetermined length) holding on a redd, and one jack male carcass (46 cm FL). Seven adult steelhead were observed in this reach (4 fish on January 9 th and 3 fish on January 30 th ), including one male, two females, and four fish of undetermined sex (50 to 56 cm FL). A total of three coho redds, 11 steelhead redds, and five redds of unknown origin were observed in Reach D (see dates for redd observations in Table 4). Chileno Creek (upstream of Walker Creek confluence) The lower portion of Chileno Creek (approximately 0.75 miles) was surveyed only once on January 19, No fish or redds were observed and spawning habitat was minimal, so this reach was not surveyed again Genetic Analysis Genetic analysis of the tissue samples taken from the two coho salmon carcasses encountered during the 2006/2007 surveys has not been reported to MMWD. was not complete at the time of this report; these results will be reported by MMWD as soon as they are available. 4.3 Winter 2007/2008 Spawner Surveys No adult coho salmon (live fish or carcasses) were observed during the 2007/2008 spawner surveys; however, four coho redds were observed indicating the presence of coho spawners in Walker Creek. The first of these coho redds was observed on December 27, 2007, demonstrating that adult coho had returned to Walker Creek from the ocean. The remaining three coho redds were observed after CDFG released 57 adult coho into Walker Creek on January 18, We believe that the latter three coho redds may have been made by planted adults. 12

18 A total of 16 adult steelhead (11 live fish and 5 carcasses) and 46 steelhead redds were observed. In addition, nine unknown adult salmonids and five redds of uncertain origin (i.e., either coho or steelhead) were observed. Fish observations from the 2007/2008 spawner surveys are summarized in Table 5. The locations of these observations within each survey reach are illustrated in Figure 4. Coho redds observed during the 2007/2008 spawning season averaged 7.0 meters total length (pit plus tail spill), 3.8 meters total width (maximum width), and 0.22 meters in depth. Steelhead redds were smaller on average (1.2 meters total length, 1.1 meters total width, and 0.17 meter depth). Redd observations are summarized in Table 6. The locations of these observations within each survey reach are also illustrated in Figure 4. Water temperatures in Walker Creek ranged from 5.5 to 12.0 C during the 2007/2008 spawner surveys and air temperatures ranged from 1.0 to 14.0 C. Discharge ranged 7 to 36 cfs in mainstem Walker Creek during our surveys (although mainstem flows were much higher on other days during the 2007/2008 spawning season, including some days when tributaries only were surveyed). Visibility in the mainstem ranged from 0.1 to greater than 1.0 meter (i.e., from very poor to excellent water clarity). Water temperatures in Frink Canyon Creek and Salmon Creek ranged from 7.0 to 17.5 C and from 8.5 to 10.0 C, respectively during our 2007/2008 surveys. Air temperature ranged from 8.0 to 9.0 C and from 10.5 to 17.0 C, respectively in these tributaries. Visibility in Frink Canyon Creek ranged from 0.8 to greater than 1.0 meter (i.e., between good and excellent clarity), and in Salmon Creek from 0.6 to greater than 1.0 meter (i.e., between fair and excellent clarity). Frequent rains, elevated flows, and high turbidity limited our capacity to complete spawner surveys as consistently and effectively as desired during the 2007/2008 season. Persistent high flows, high turbidity, and poor water clarity precluded surveys in the mainstem of Walker Creek after mid-january. Poor visibility persisted even during periods of lower flow due to highly turbid water spilling over Soulajule Dam and/or being released from Soulajule Reservoir. The reservoir became mixed during winter storms, which impacted water clarity to the point where surveys could not effectively be conducted in the mainstem of Walker Creek. Thus, for the latter half of the spawning season, only Salmon Creek (part of Reach B) and Frink Canyon Creek (part of Reach C) were surveyed. Observations are detailed per reach below. Reach A (Soulajule Reservoir downstream to Salmon Creek confluence) Reach A was surveyed four times (November 29 th, December 13 th, December 27 th, and January 15 th ). No live adult coho salmon, carcasses, or redds were observed in Reach A. No adult steelhead (live fish or carcasses) or steelhead redds were observed in this reach. High flows and persistent high turbidity (even during periods of lower flow) precluded any surveys through this reach following the January 15, 2008 survey. 13

19 Reach B (Salmon Creek confluence to Marshall-Petaluma Road, plus one mile of Salmon Creek) Reach B was surveyed in its entirety (mainstem Walker Creek plus Salmon Creek) four times (November 29 th, December 13 th, December 27 th, and January 15 th ), and Salmon Creek alone was surveyed three additional times (February 8 th, February 19 th, and March 10 th ). No adult coho salmon (live fish or carcasses) were observed in Reach B. However, four separate coho redds were observed in this reach; one redd in the mainstem portion, and three redds in Salmon Creek (see Figure 4). The first coho redd was observed prior to the January 2008 release of adult coho into Walker Creek by CDFG and the remaining three redds were observed following the release. Additionally, 12 adult steelhead (10 live fish, including 3 male/female pairs on redds, and 2 carcasses) were observed in Reach B, along with seven other unidentifiable adult salmonids (likely steelhead). A total of 16 steelhead redds were observed in Reach B (including many in Salmon Creek). Four redds of uncertain origin were also observed in Reach B (see dates for redd observations in Table 6). High flows and persistent high turbidity (even during periods of lower flow) precluded any surveys through the mainstem Walker Creek portion this reach after the January 15, 2008 survey. Reach C (Marshall-Petaluma Road to bottom of Walker Creek Ranch) Reach C was surveyed in its entirety (mainstem Walker Creek plus Frink Canyon Creek) four times (November 29 th, December 13 th, December 27 th, and January 15 th ), and Frink Canyon Creek alone was surveyed three additional times (February12 th, February 19 th, and March 10 th ). No adult coho salmon (live fish or carcasses) and no coho redds were observed in Reach C. Four adult steelhead (1 live fish and 3 carcasses) were observed in Reach C, along with one other unidentifiable adult salmonid (likely a steelhead). A total of 29 steelhead redds were observed in Reach C (including many in Frink Canyon Creek). One redd of uncertain origin was also observed in Reach C (see dates for redd observations in Table 6). High flows and persistent high turbidity (even during periods of lower flow) precluded any surveys through the mainstem Walker Creek portion this reach after the January 15, 2008 survey. Reach D (bottom of Walker Creek Ranch to Chileno Creek confluence) A portion of Reach D was only surveyed once (on January 24 th ). Due to restricted access, only the upstream-most 0.3 miles of Reach D could be surveyed (along the Walker Creek Ranch property below Zwart Bridge). No adult salmonids (live fish or carcasses) were observed in this section, and only one steelhead redd was seen during this limited survey. Turbidity was high and visibility was quite poor during the January 24 th survey, and persistent high turbidity precluded any further surveys. 14

20 Walker Creek (left) at Salmon Creek confluence Salmon Creek 15

21 4.3.1 Genetic Analysis No adult coho salmon tissue samples were collected during the 2007/2008 spawning season for genetic analysis. 4.4 Winter 2008/2009 Spawner Surveys No adult coho salmon (live fish or carcasses) were observed during the 2008/2009 spawner surveys; however, one coho redd were observed indicating the presence of coho spawners in Walker Creek. The coho redd was observed on January 23 rd, 2009, demonstrating that at least one spawning pair of adult salmon returned to Walker Creek from the ocean. No adult steelhead (live fish or carcasses) were documented in Walker Creek but 17 steelhead redds were observed. In addition, 2 redds of uncertain origin (i.e., either coho or steelhead) were observed. The single coho redd observed during the 2008/2009 spawning season measured 6.4 meters in total length (pit plus tail spill), 3.2 meters total width (maximum width), and 0.5 meters in depth. Steelhead redds were smaller on average (2.9 meters total length, 1.2 meters total width, and 0.14 meter depth). Redd observations are summarized in Table 7. Water temperatures in Walker Creek ranged from 7.0 to 11.0 C during the 2008/2009 spawner surveys and air temperatures ranged from 4.0 to 16.0 C. Discharge ranged 6.5 to 18 cfs in mainstem Walker Creek during our surveys (although mainstem flows were much higher on other days when surveys were not conducted during the 2008/2009 spawning season). Visibility in the mainstem ranged from 0.5 to greater than 1.0 meter (i.e., from fair to excellent water clarity). Surveys were not limited by elevated flows, high turbidity, or reduced water clarity during the 2008/2009 spawning season because winter rains never occurred frequently enough to cause Soulajule Reservoir to spill into mainstem Walker Creek. Reach A (Soulajule Reservoir downstream to Salmon Creek confluence) Due to low coho abundance, reach A was only surveyed once on March 19 th. No coho or steelhead observations were made. Reach B (Salmon Creek confluence to Marshall-Petaluma Road, plus one mile of Salmon Creek) Reach B was surveyed in its entirety (mainstem Walker Creek plus Salmon Creek) two times (February 12 th and March 19 th ), and the mainstem of Walker Creek excluding the mile of salmon creek was surveyed three times (November 21 st, December 31 st, and January 23 rd ). Salmon Creek was excluded from surveys on these dates because of low flows. No adult coho salmon (live fish or carcasses) were observed in Reach B. 16

22 However, one coho redd was observed in the mainstem Walker Creek portion of this reach. Additionally, a total of 5 steelhead redds were observed in mainstem Walker Creek of Reach B. Two redds of uncertain origin were also observed in reach B, both in mainstem Walker Creek (see dates for redd observations in Table 7). Reach C (Marshall-Petaluma Road to bottom of Walker Creek Ranch) Reach C was surveyed in its entirety (mainstem Walker Creek plus Frink Canyon Creek) four times (December 31 st, January 23 rd, February 12 th, and March 19 th ), and mainstem Walker Creek alone was surveyed one time on November 21 st (Frink Canyon Creek was not surveyed on this date because it was dry). No adult coho salmon (live fish or carcasses) and no coho redds were observed in Reach C. No adult steelhead (live fish or carcasses) were observed in Reach C but a total of 12 steelhead redds were observed (including two in Frink Canyon Creek). Reach D (bottom of Walker Creek Ranch to Chileno Creek confluence) Due to property access issues, reach D was not surveyed during the 2008/2009 spawning season Genetic Analysis No adult coho salmon tissue samples were collected during the 2008/2009 spawning season for genetic analysis. 4.5 Winter 2009/2010 Spawner Surveys No adult coho salmon (live fish or carcasses) were observed during the 2009/2010 spawner surveys; however, two coho redds were observed indicating the presence of coho spawners in Walker Creek. Both coho redds were observed on December 17 th, A total of 4 adult steelhead (4 live fish, 0 carcasses) and 12 steelhead redds were observed. In addition, one redd of uncertain origin (i.e., either coho or steelhead) was observed. Fish observations from the 2009/2010 spawner surveys are summarized in Table 8. Coho redds observed during the 2009/2010 spawning season averaged 4.3 meters total length (pit + tail spill), 2.3 meters total width (maximum width), and 0.2 meters in depth. Steelhead redds were smaller on average (2.8 meters total length, 1.3 meters total width, and 0.16 meters in depth). Redd observations are summarized in Table 9. Water temperatures in Walker Creek ranged from 8.0 to 10.5 C during the 2009/2010 spawner surveys and air temperatures ranged from 8.0 to 12.5 C. Discharge ranged 7 17

23 to 38 cfs in mainstem Walker Creek during our surveys (although mainstem flows were much higher on other days during the 2009/2010 spawning season when no surveys were conducted). Visibility in the mainstem ranged from 0.4 to greater than 1.0 meter (i.e., from poor to excellent water clarity). Although Soulajule Reservoir did spill during the 2009/2010 spawner season, surveys in Walker Creek were not limited by elevated flows, high turbidity, or reduced water clarity because long enough breaks between rain storms allowed all surveys to be completed successfully. Reach A (Soulajule Reservoir downstream to Salmon Creek confluence) Due to low coho abundance, reach A was not surveyed during the 2009/2010 spawning season. Reach B (Salmon Creek confluence to Marshall-Petaluma Road, plus one mile of Salmon Creek) Reach B was surveyed in its entirety (mainstem Walker Creek plus Salmon Creek) twice on December 17 th and February 19 th, and the mainstem of Walker Creek excluding the mile of salmon creek was surveyed twice on December 4 th and January 8 th. No adult coho salmon (live fish or carcasses) were observed in Reach B. However, two separate coho redds were observed in this reach; both in the mainstem Walker Creek portion of section B. Additionally, three adult steelhead (3 live fish, including 1 male/female pair on a redd and 0 carcasses) and a total of 7 steelhead redds were observed in Reach B (all in the mainstem of Walker Creek). Reach C (Marshall-Petaluma Road to bottom of Walker Creek Ranch) Reach C was surveyed in its entirety (mainstem Walker Creek plus Frink Canyon Creek) two times (December 17 th and February 19 th ), and mainstem Walker Creek alone was surveyed two times (December 4 th and January 8 th ). No adult coho salmon (live fish or carcasses) and no coho redds were observed in Reach C. One adult steelhead (1 live fish and 0 carcasses) and a total of 5 steelhead redds were observed in Reach C (all in mainstem Walker Creek). One redd of uncertain origin was also observed in Reach C (see dates for redd observations in Table 9). Reach D (bottom of Walker Creek Ranch to Chileno Creek confluence) Due to property access issues, reach D was not surveyed during the 2009/2010 spawning season 18

24 Walker Creek mainstem Walker Creek mainstem at USGS gage station 19

25 4.5.1 Genetic Analysis No adult coho salmon tissue samples were collected during the 2009/2010 spawning season for genetic analysis Juvenile Coho Salmon Surveys Snorkel Surveys Water clarity in mainstem Walker Creek was very poor during the 2006 juvenile surveys. Soulajule Reservoir apparently experienced turnover prior to our October 2006 surveys, creating highly turbid conditions downstream. Visibility was less than one foot in Walker Creek throughout the fall of Unfortunately, poor visibility limited the ability to identify the few fish observed in the mainstem during snorkel surveys. Water clarity in tributary streams, however, was excellent during the 2006 juvenile surveys. Tributaries generally consisted of isolated pools connected by sub-surface flow or small surface trickles. Most pools appeared to provide suitable refugia for fish, with relatively cool water temperatures and adequate cover. Fish species observed during 2006 snorkel surveys included steelhead, California roach (Hesperoleucus symmetricus), sculpin (Cottus sp.), sunfish (Lepomis sp.), and threespine stickleback (Gasterosteus aculeatus). No coho salmon were observed. Steelhead, roach, and sculpin were the primary species observed as detailed below. Walker Creek Mainstem Walker Creek was surveyed from the downstream end of Walker Creek Ranch up to Soulajule Reservoir (approximately 6 stream miles) during October Water clarity in the mainstem was very poor, typically less than one foot. A few steelhead were observed while feeding on insects floating on the water s surface, and several juvenile roach were also observed along the stream margins. However, no coho salmon were observed in the mainstem of Walker Creek. Frink Canyon Creek Frink Canyon Creek was surveyed from its confluence with Walker Creek to approximately one-quarter mile upstream during October Dense vegetation restricted access to the channel upstream of this point. Several steelhead were observed in the few small pools present in this reach; these fish were approximately mm FL. No other fish species were observed. Verde Canyon Creek Verde Canyon Creek was surveyed from its confluence with Walker Creek to just above the Marshall-Petaluma Road crossing (approximately 0.75 stream miles) during October Upstream of the Marshall-Petaluma Road crossing, the channel was drier and dense vegetation further restricted access to the channel. Additionally, the culvert at this 20

26 road crossing appears to serve as a barrier to upstream fish migration under most flow conditions (no flow was present through the culvert at the time of our survey). Fish were observed in four isolated pools in the reach below the Marshall-Petaluma Road crossing. A total of six steelhead were observed (all in the mm FL range) along with numerous roach and several sunfish. No coho salmon were observed. Cattle appeared to have free access to the channel in this reach. Above the Marshall- Petaluma Road crossing, three isolated pools were surveyed containing numerous stickleback (the only species observed above the culvert). Salmon Creek Salmon Creek was surveyed from its confluence with Walker Creek to the upstream extent of the study area (approximately 1 stream mile) during October This larger tributary had more frequent and larger-sized pools, with higher fish abundances. A few pools associated with bedrock outcrop features were several feet deep. Steelhead, roach, and sculpin were numerous. An estimated steelhead of various age classes (young-of-the-year [YOY] and age 1+ fish) were observed in 44 isolated pools in this reach. Roach were equally numerous and present in all pools. Sculpin were observed mostly in larger pools. No coho salmon were observed. Cattle had access to the channel throughout most of this reach Electrofishing Surveys Qualitative electrofishing also did not produce any juvenile coho salmon during the October 2006 surveys. Approximately 300 juvenile steelhead were collected; most of these fish ranged from mm FL. One larger steelhead measured 360 mm FL. Other species collected from Walker Creek during electrofishing included roach, sculpin, and several sunfish. Isolated pools surveyed in the lower portion of Verde Canyon Creek contained predominantly roach along with several juvenile steelhead Genetic Analysis No juvenile coho salmon tissue samples were collected during 2006 electrofishing surveys for genetic analysis Juvenile Coho Salmon Surveys Snorkel Surveys A total of 193 juvenile coho salmon were observed in the study area during 2007 snorkel surveys (conducted during August and September). Other fish species observed included steelhead, roach, sculpin, and three-spine stickleback. Roach and steelhead were the most abundant species observed. The distribution of juvenile coho salmon observed during snorkel surveys is illustrated in Figure 5. A list of all fish present in each pool where coho were observed is provided in Table

27 Visibility in mainstem Walker Creek was between 1.0 m and 1.5 m during most of the 2007 juvenile surveys. One exception was the reach approximately 1 km downstream of the confluence with Salmon Creek where locally high turbidity prohibited effective snorkeling. Water clarity was extremely poor and visibility was less than 0.1 m in this section due to presence of cattle in the stream; no snorkel surveys could be performed in this section. Water clarity in tributary streams was excellent during the 2007 snorkel surveys. Tributaries generally consisted of isolated pools connected by sub-surface flow or small surface trickles. Most pools appeared to provide suitable refugia for fish, with relatively cool water temperatures and adequate cover. Walker Creek Mainstem Juvenile coho salmon were observed throughout the six miles of the mainstem surveyed in In general, coho were more abundant in the upper portion of the mainstem (between the Marshall-Petaluma Road Bridge and the confluence with Salmon Creek) and less abundant in the lower portion (near the downstream end of the Walker Creek Ranch property see Figure 5). Coho were consistently observed holding and feeding near the head of pools with adequate structure and woody cover (typically a few coho per pool among larger schools of steelhead and roach, although one pool contained as many as 29 juvenile coho - see Table 10). During our August 2007 surveys, juvenile coho were between 50 and 90 mm TL. Steelhead and roach and were by far the most abundant species observed. Some three-spine stickleback and sculpin were also observed. Frink Canyon Creek Frink Canyon Creek was surveyed from its confluence with Walker Creek to approximately one-quarter mile upstream. Dense vegetation restricted access to the channel upstream of this point. A total of 21 juvenile coho salmon (along with 7 steelhead) were observed in two of the isolated pools present in the lower portion of this reach (see Figure 5); these fish were approximately mm TL during our August 2007 survey. No other fish species were observed in Frink Canyon Creek. Verde Canyon Creek Verde Canyon Creek was surveyed from its confluence with Walker Creek to just above the Marshall-Petaluma Road crossing (approximately 0.75 stream miles). Upstream of the Marshall-Petaluma Road crossing, the channel was drier and dense vegetation further restricted access to the channel. Additionally, the culvert at this road crossing appears to serve as a barrier to upstream fish migration under most flow conditions (no flow was present through the culvert during our August 2007 survey). Steelhead, roach, and three-spine stickleback were observed in the pools in the reach below the Marshall- Petaluma Road crossing. No coho salmon were observed in Verde Canyon Creek. 22

28 Salmon Creek Salmon Creek was surveyed from its confluence with Walker Creek to the upstream extent of the study area (approximately 1 stream mile). This larger tributary had more frequent and larger-sized pools, with higher fish abundances than other tributaries. Steelhead and roach were abundant and present in all pools; sculpin were also common. Only five juvenile coho salmon were observed in Salmon Creek in 2007, all in a single pool located a few hundred meters upstream of the confluence with Arroyo Sausal (see Figure 5). These fish were between 70 and 90 mm TL Electrofishing Surveys Qualitative one-pass electrofishing conducted in portions of the study area during September and October 2007 produced 17 juvenile coho salmon (along with 172 steelhead, and numerous roach that were not counted, plus several scuplin and threespine stickleback that also were not counted). These juvenile coho were between 44 and 90 mm FL (i.e., similar in size to those fish observed during August 2007 snorkel surveys). Tissue samples (fin clips) were collected from each coho specimen for genetic analysis. A summary of 2007 electrofishing data for coho salmon and steelhead is provided in Table Genetic Analysis Genetic analysis of the tissue samples taken from the 16 juvenile coho salmon specimens collected during 2007 electrofishing surveys was not complete at the time of this report; these results will be reported by MMWD as soon as they are available Juvenile Coho Salmon Surveys Snorkel Surveys A total of 19 juvenile coho salmon were observed in the study area during snorkel surveys conducted during late August Other fish species observed included steelhead, roach, sculpin, and three-spine stickleback. Roach and steelhead were the most abundant species observed. The distribution of juvenile coho salmon observed during snorkel surveys is illustrated in Figure 5. A list of all fish present in each pool where coho were observed is provided in Table 12. Visibility in mainstem Walker Creek was between 1.0 m and 2.0 m during most of the 2008 juvenile surveys. One exception was the reach approximately 1 km downstream of the confluence with Salmon Creek where locally high turbidity prohibited effective snorkeling. Water clarity was extremely poor and visibility was less than 0.1 m in this section due to presence of cattle in the stream; no snorkel surveys could be performed in this section. Water clarity in Frink Canyon and Salmon creeks was excellent during the 2008 snorkel surveys. Tributaries generally consisted of isolated pools connected by sub-surface flow 23

29 or small surface trickles. Most pools appeared to provide suitable refugia for fish, with relatively cool water temperatures and adequate cover. Water quality in Verde Canyon Creek was poor with the cattle waste. Walker Creek Mainstem Juvenile coho salmon were observed throughout the six miles of the mainstem surveyed in In general, coho were more abundant in the upper portion of the mainstem (between the Marshall-Petaluma Road Bridge and the confluence with Salmon Creek) and less abundant in the lower portion (near the downstream end of the Walker Creek Ranch property see Figure 5). Coho were consistently observed holding and feeding near the head of pools with adequate structure and woody cover (typically 1-2 coho per pool among larger schools of steelhead and roach). During our August 2008 surveys, juvenile coho were between 80 and 95 mm TL. Steelhead and roach and were by far the most abundant species observed. Some three-spine stickleback and sculpin were also observed. Frink Canyon Creek Frink Canyon Creek was surveyed from its confluence with Walker Creek to approximately one-quarter mile upstream. Dense vegetation restricted access to the channel upstream of this point. A total of 2 juvenile coho salmon (along with 13 steelhead) were observed in two of the isolated pools present in the lower portion of this reach (see Figure 5). Verde Canyon Creek Verde Canyon Creek was surveyed from its confluence with Walker Creek to just above the Marshall-Petaluma Road crossing (approximately 0.75 stream miles). Upstream of the Marshall-Petaluma Road crossing, the channel was drier and dense vegetation restricted access to the channel. Additionally, the culvert at this road crossing appears to serve as a barrier to upstream fish migration under most flow conditions (no flow was present through the culvert at the time of the survey). Steelhead, roach, and three-spine stickleback were observed in the pools in the reach below the Marshall-Petaluma Road crossing. No juvenile coho salmon were observed in Verde Canyon Creek. Salmon Creek Salmon Creek was surveyed from its confluence with Walker Creek to the upstream extent of the study area (approximately 1 stream mile). This larger tributary had more frequent and larger-sized pools, with higher fish abundances than other tributaries. Steelhead and roach were abundant and present in all pools; sculpin were also common. No juvenile coho salmon were observed in Salmon Creek in Electrofishing Surveys Qualitative one-pass electrofishing conducted in portions of the study area during October 2008 produced 1 juvenile coho salmon (along with 180 steelhead, and numerous roach that were not counted, plus several scuplin and three-spine stickleback 24

30 that also were not counted). A tissue sample (fin clip) was collected from the coho specimen for genetic analysis. Table Genetic Analysis Genetic analysis of the tissue samples taken from the 1 juvenile coho salmon specimens collected during 2008 electrofishing surveys was not complete at the time of this report; these results will be reported by MMWD as soon as they are available. 4.9 Water Temperature Data Mean daily water temperatures in Walker Creek below Soulajule Reservoir fluctuated between 9.0 and 17.4 C during the monitoring period and the peak in mean weekly maximum temperatures (MWMT) varied between 18.4 and 24.3 C (see Appendix A). Between April and August, Walker Creek warmed as it flowed downstream, eventually warming by C at its confluence with (and upstream of) Keys Creek. Four sites reached a peak daily water temperature on July 22, 2007 of between 18.0 and 21.7 C. Beginning in September and continuing through January, Walker Creek cooled as it flowed downstream. Summer water temperatures in Chileno Creek (Site 7) were cooler than at almost any other location, with mean daily temperatures reaching only16.8 C in late July. The other two tributaries, Salmon Creek and Frink Canyon, differed substantially from each other in their temperature characteristics. Salmon Creek (Site 2) was one of the warmest locations throughout the summer, but then was one of the coolest locations starting in the fall (Figure 3). Frink Canyon (Site 4) was consistently one of the coolest locations throughout the monitoring period Benthic Macroinvertebrate Data Walker Creek Ranch provided GANDA with seven data sheets from the fall of 2007, representing four sampling dates. Unfortunately, this appears to be the entire data output from the BMI sampling effort. There was wide variation in the level of effort and detail recorded on the data sheets from the four sampling events (e.g., only one datasheet was completely filled out). Despite the preparation and training provided by GANDA, it appears that the protocols were not systematically followed, and sample collection and processing efforts varied considerably. From the limited information that was received, it appears that students identified caddisflies, mayflies, and true bugs (Hemipterans) as the most abundant organisms in Walker Creek BMI samples (see Table 14 and Appendix B). In January 2009, GANDA collected Targeted Riffle and Multi-habitat samples from the Alder Flat and Sandy Flat sites (see Figure 6 and Appendix B) to serve as a baseline for comparisons with future invertebrate collections. Over 57,000 benthic macroinvertebrates were collected from the two sites on Walker Creek in 2009 (in TRC and MH samples combined; see Table 15). Of these individuals, 2,148 specimens were 25

31 identified, representing 49 taxa from 37 families and 12 taxonomic orders. The most common taxa in these samples included the mayflies Baetis spp. and Diphetor hageni (Baetidae), the case-making Trichoptera Gumaga (Sericostomatidae), the beetle Optioservus (Elmidae), and chironomid midges. Walker Creek mainstem 26

32 5.0 CONCLUSIONS 5.1 Adult Spawner Surveys Results of the spawner surveys confirmed that the planted adult coho successfully spawned and, perhaps more importantly, that adult coho salmon returned from the ocean to spawn in Walker Creek. However, the relatively low numbers of spawners and redds observed, especially during the 2008/2009 and 2009/2010 spawner seasons, suggest that the coho population in Walker Creek remains poorly established. By comparison, the steelhead population in Walker Creek appears relatively robust. In California, coho salmon typically spawn between November and January, and fry typically emerge from the gravel the following spring between March and May (Hassler 1987). Juvenile coho typically reside in California streams for their first year before emigrating to the ocean, where they spend the next two years. Coho typically return to spawn as three-year-old adults, although a few precocious males (referred to as jacks ) return after one year in the ocean (i.e., as 2-year-olds). Therefore, it is very likely that the adult coho salmon and the eggs in the coho redds that we observed during the spawner surveys, beginning with the 2006/07 season, were the progeny of the planted coho. The coho salmon returning to Walker Creek during the winter of 2006/2007 were most likely born in the spring of 2004, after their parents had been released into the creek, and emigrated to the ocean in the spring of Likewise, adult coho present during the 2007/2008 spawning season were most likely born in the spring of 2005, also as the progeny of planted adults, and emigrated to the ocean in spring of Thus, it is possible that these fish may either be the progeny of wild fish, or of the adult spawners released into Walker Creek as part of the CDFG stocking effort in the winters of 2003/2004 and 2004/2005. The jack male coho (2 carcasses) observed during the 2006/2007 spawner surveys were also likely born in the spring of 2005, and emigrated to the ocean in spring of These fish could be the progeny of wild fish, or of the adult spawners released into Walker Creek in the winter of 2004/2005. We presume that the adult coho we observed were the progeny of the planted fish. The results of the genetic analysis of tissue samples from the few carcasses we collected should allow definitive determination of the origin of these fish. Storm flows during the winters of 2003/2004 and 2004/2005 (i.e., when most of the spawners observed during 2006/2007 would have been present in egg, fry, or juvenile stages in Walker Creek) were relatively moderate (see Table 16). Peak discharges for these winters were 794 cfs on January 1, 2004, and 647 cfs on March 22, Jack males returning in 2006/2007, and three-year-old adults returning in 2007/2008, would have been present in Walker Creek at the end of their first year during some portion of the winter of 2005/2006, which was characterized by much higher peak flows (4,130 cfs on December 31, 2005). For the 2005/2006 spawning season, redds established prior to December 31, 2005 were probably destroyed during this flood, and redds established 27

33 after December 31, 2005, as well as newly emerging fry, may have been impaired by the subsequent high flows (e.g., flows reached 1,090 cfs on March 22, 2006). However, one-year-old juvenile coho still present in Walker Creek during that time period may have been able to ride out these flood flows. Widespread declines in adult coho salmon returns during the 2007/2008 season may be more likely attributable to poor ocean conditions (i.e., low ocean productivity) off the California coast during the spring and summer of 2006, when juvenile fish from the 2004/2005 spawn (i.e., jacks observed in 2006/2007 and 3-year-old spawners observed in 2007/2008) would have entered the ocean as smolts (see MacFarlane et al 2008). The single coho redd observed during the 2008/2009 spawning season could have either been made by returning offspring of the adult coho planted in 2005/2006 or by returning coho that had been released as smolts in The two coho redds observed during the 2009/2010 season could have been made by third generation offspring of the coho adults planted in 2003/2004; previously observed as juveniles in the summer of 2007 (see Table 1). 5.2 Juvenile Coho Salmon Surveys Snorkel and electrofishing surveys of the study area during October 2006 found no juvenile coho salmon. While high turbidity and poor visibility limited the effectiveness of snorkel surveys in mainstem Walker Creek, qualitative electrofishing surveys conducted in 2006 (which also produced no coho) appear to support the conclusion that few, if any, juvenile coho salmon were present in the study area during This apparent absence of juvenile coho may be the result of large storms that hit the region during the preceding winter of 2005/2006. As discussed above, that winter was marked by several large storms, the largest of which hit the region in late December (flows in the study area reached 4,130 cfs on December 31, 2005 and remained over 1,000 cfs through January 2, 2006). This storm caused large-scale scouring of the streambed and banks. Adult spawners that were planted in Walker Creek for the 2005/2006 spawning season were released prior to December 31, 2005, and were thus subjected to these flood flows while in the creek. A flow event of this magnitude could have displaced many fish, and would have effectively scoured most coho redds, thereby reducing or potentially eliminating coho production for the 2005/2006 spawning season. Other large storms that brought additional high flows to Walker Creek later that same winter may have further impacted coho production for the season. By contrast, snorkel surveys conducted in 2007 documented the presence of nearly 200 juvenile coho salmon in Walker Creek and its tributaries. Although CDFG planted 3,400 coho smolts in the mainstem of Walker Creek prior to our surveys, we believe that all of the juvenile coho observed during 2007 snorkeling and electrofishing surveys were the progeny of the adult spawners from the preceding winter (2006/2007), not planted smolts. All of the fish observed during our August-October surveys were less than 100 mm TL, whereas all the smolts planted in June by CDFG were at least 100 mm TL and most were much larger at the time of their release (pers. comm. Gregory Andrew, MMWD). 28

34 In 2008, we again found juvenile coho in Walker and Frink Canyon creeks, providing evidence of successful spawning during the winter of 2007/2008. Unfortunately, the number observed was approximately one tenth of the number observed in This decrease could be the result of myriad factors, but poor ocean conditions as evidenced by very low returns throughout the west contributed significantly to the low numbers. The presence of juvenile coho salmon in Walker Creek, Frink Canyon Creek, and Salmon Creek during 2007 and 2008 snorkel and electrofishing surveys indicates that successful spawning of returning adults occurred during the winters of 2006/2007 and 2007/2008 in both the mainstem and its tributaries. In general, the successful spawning and rearing of coho salmon in Walker Creek is encouraging and may be related to some success from the planting of coho into Walker Creek. 5.3 Water Temperature Monitoring There does appear to be some cooling or stabilization of water temperatures within the central portion of Walker Creek, in the stretch between data logger locations 3 and 6 (see Appendix A). A slight but consistent drop in temperature was documented between Sites 3 and 5, throughout the year, which may be from shading provided by the riparian vegetation. A cooling effect from the colder water coming out of Frink Canyon could be a factor but even during the summer months, when Frink Canyon is just a trickle or even dry, water temperatures at Site 5 were slightly cooler than at Site 3. There could also be groundwater contributions helping to keep temperatures cooler at Site 5 than Site 3. Water temperatures remained fairly stable and only rose slightly between Sites 5 and 6. Site 6, having been located upstream of Chileno Creek, was not influenced by cooler Chileno Creek water. Temperatures noticeably warmed between Site 6 above Chileno Creek and Site 8 just upstream from Highway Benthic Macroinvertebrate Monitoring The 2009 results provide an important baseline condition for this reach of Walker Creek, which can be compared to other sites or future measures as environmental and landuse factors change in the future. Based on 2009 TRC samples, biological condition appeared very similar between the Sandy Flat and Alder Flat sites, with the Nor Cal IBI scores for both sites representing fair biological condition. Both sites had fairly low taxa richness in both samples (TRC=33 and 27 taxa in Sandy Flats and Alder Flats, respectively; MH=30 taxa in both sites), which is fairly common for streams in Marin County (Jon Lee, personal communications). These taxa richness scores were similar, although slightly higher, to those found during the SWAMP bioassessment of different sites in Walker Creek in In terms of composition measures, EPT richness was higher in the TRC sample from Sandy Flats that in the other samples (16 vs. 11 and 11 vs. 12; TRC vs. MH at Sandy Flats and Alder Flats respectively). Percent Sensitive EPT composition was similar between sites and higher in both TRC samples (28.7% vs. 13.2% and 22.7% vs. 13.5%; TRC vs. MH at Sandy Flats and Alder Flats respectively). 29

35 The BMI monitoring program initiated in 2007 was not implemented in a manner that produced useful data for scientific purposes. While the program met with some success in terms of is educational value for students and youth groups that participated, none of the data generated are adequate for monitoring or planning purposes. The lack of detail in effort and data recording makes it impossible to determine the comparability of these sampling events to each other or to any future efforts. The reliability of these data is also uncertain because students tended to primarily identify the more conspicuous and observable organisms (e.g., caddisflies, mayflies, and true bugs). It is more typical, for example, that true flies (Diptera) dominated by the family Chironomidae are the most abundant taxa in the stream, which appeared to be the case during GANDA s preliminary sampling, field training efforts, and 2009 sampling. Therefore, it seems likely that the many organisms such as small dipterans were missed and not identified in most samples. This assertion is further supported by macroinvertebrate data collected in 2009 by GANDA where over 36 percent of the organisms sampled were dipterans, as compared to only 25 percent Ephemeroptera, 2 percent Plecoptera, and 16 percent Trichoptera. Therefore, GANDA recommends that if the BMI monitoring program at Walker Creek Ranch is continued in the future, a well-trained staff member should be appointed to oversee field procedures and provide data QA/QC. It is also recommended that at least two training workshops be conducted to ensure the staff is well equipped and adequately prepared to lead the field sampling efforts. Walker Creek mainstem 30

36 6.0 ACKNOWLEDGEMENTS MMWD and GANDA would like to acknowledge and thank the California Department of Fish and Game and the Fishery Restoration Grant Program for funding this monitoring program, with special thanks to Manfred Kittel and Gail Seymour who coordinated the coho plantings into Walker Creek. We would also like to thank the Marin County Office of Education, the McDonald family, the Gambonini family, the Thatcher family, and the Kleiser family for granting us access to their property to conduct the surveys. Additionally, we want to thank the staff and students at Walker Creek Ranch for assisting with the monitoring, and the Marin County Resource Conservation District for helping to arrange access to the study area. This compilation report was prepared by staff at Garcia and Associates, with editing and additional portions provided by the Marin Municipal Water District. Contributors to this compilation report include the following individuals: Garcia and Associates Rob Aramayo, Aquatic Ecologist Ian Chan, Aquatic Ecologist Dr, JoAnna Lessard, Senior Aquatic Ecologist Marin Municipal Water District Gregory Andrew, Fishery Program Manager Eric Ettlinger, Aquatic Ecologist Andrew Wolf, Watershed Aide Roger Brindle, Maintenance Worker I Coho salmon, immediately after being released into Walker Creek 31

37 7.0 REFERENCES Andrew, Gregory. MMWD. Personal communication regarding coho plantings and smolt sizes. Aramayo, Rob and I. Chan. Garcia and Associates. 2007a Walker Creek Juvenile Coho Salmon Surveys. Memorandum report to Gregory Andrew, MMWD; May 21, pp. plus appendices (21 pp. total). Aramayo, Rob and I. Chan. Garcia and Associates. 2007b. 2006/2007 Walker Creek Adult Coho Salmon Surveys. Memorandum report to Gregory Andrew, MMWD; August 24, p. plus appendices (85 pp. total). Aramayo, Rob and I. Chan. Garcia and Associates. 2008a Walker Creek Juvenile Coho Salmon Surveys. Memorandum report to Gregory Andrew, MMWD; March 28, pp. plus appendices (29 pp. total). Aramayo, Rob and I. Chan. Garcia and Associates. 2008b Walker Creek Adult Coho Salmon Surveys. Memorandum report to Gregory Andrew, MMWD; August 24, p. plus appendices (103 pp. total). Aramayo, Rob and I. Chan. Garcia and Associates Walker Creek Juvenile Coho Salmon Surveys. Memorandum report to Gregory Andrew, MMWD; February 11, pp. plus appendices (28 pp. total). Garcia and Associates (GANDA) Walker Creek Macroinvertebrate Bioassessment: Final Report. Prepared by GANDA; prepared for Marin Municipal Water District and California Department of Fish and Game; March pp plus appendices (13pp. total). Hammack, Lauren Geomorphology of the Walker Creek Watershed: Projects for Habitat Enhancement and Sediment Management. Prepared by Prunuske Chatham, Inc for Marin Resource Conservation District. 56 pp. Hassler, T. J Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Pacific Southwest) Coho Salmon. U.S. Fish and Wildlife Service Biological Report 82(11.70). U.S. Army Corps of Engineers. TR EL pp. Kittel, Manfred. CDFG Associate Fishery Biologist. January 30, Personal communication, regarding coho plantings. Lessard, JoAnna. Garcia and Associates Aquatic macroinvertebrate monitoring program for Walker Creek Ranch. Memorandum report to Gregory Andrew, MMWD; March 26, pp. plus appendices (26pp total). MacFarlane, R. B., Hayes, S., and B. Wells Coho and Chinook salmon decline in California during the spawning seasons of 2007/08. Memorandum dated February 2, pp. Marin Municipal Water District. Unpublished data, provided by Gregory Andrew, MMWD. 32

38 SWAMP Surface Water Ambient Monitoring Program. Unpublished data. Surface Water Ambient Monitoring Program (SWAMP) Standard Operating Procedures for Collecting Benthic Macroinvertebrate Samples and Associated Physical and Chemical Data for Ambient Bioassessments in California. February Prepared by the State Water Board and the CDFG Aquatic Bioassessment Laboratory. USGS Stream Gage Data An afternoon on Walker Creek 33