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USGS2014

Passage and survival probabilities of juvenile Chinook salmon at Cougar Dam, Oregon, 2012

This report describes studies of juvenile-salmon dam passage and apparent survival at Cougar Dam, Oregon, during two operating conditions in 2012. Cougar Dam is a 158-meter tall rock-fill dam used primarily for flood control, and passes water through a temperature control tower to either a powerhouse penstock or to a regulating outlet (RO). The temperature control tower has moveable weir gates to enable water of different elevations and temperatures to be drawn through the dam to control water temperatures downstream. A series of studies of downstream dam passage of juvenile salmonids were begun after the National Oceanic and Atmospheric Administration determined that Cougar Dam was impacting the viability of anadromous fish stocks. The primary objectives of the studies described in this report were to estimate the route-specific fish passage probabilities at the dam and to estimate the survival probabilities of fish passing through the RO. The first set of dam operating conditions, studied in November, consisted of (1) a mean reservoir elevation of 1,589 feet, (2) water entering the temperature control tower through the weir gates, (3) most water routed through the turbines during the day and through the RO during the night, and (4) mean RO gate openings of 1.2 feet during the day and 3.2 feet during the night. The second set of dam operating conditions, studied in December, consisted of (1) a mean reservoir elevation of 1,507 ft, (2) water entering the temperature control tower through the RO bypass, (3) all water passing through the RO, and (4) mean RO gate openings of 7.3 feet during the day and 7.5 feet during the night. The studies were based on juvenile Chinook salmon (Oncorhynchus tshawytscha) surgically implanted with radio transmitters and passive integrated transponder (PIT) tags. Inferences about general dam passage percentage and timing of volitional migrants were based on surface-acclimated fish released in the reservoir. Dam passage and apparent survival probabilities were estimated using the Route-Specific-Survival Model with data from surface-acclimated fish released near the water surface directly upstream of the temperature control tower (treatment group) and slightly downstream of the dam (control group). In this study, apparent survival is the joint probability of surviving and migrating through the study area during the life of the transmitters. Two rearing groups were used to enable sufficient sample sizes for the studies. The groups differed in feed type, and for the December study only, the rearing location. Fish from each group were divided nearly equally among all combinations of release sites, release times, and surgeons. The sizes, travel times, and survivals of the two rearing groups were similar. There were statistical differences in fish lengths and travel times of the two groups, but they were small and likely were not biologically meaningful. There also was evidence of a difference in single-release estimates of survival between the rearing groups during the December study, but the differences had little effect on the relative survival estimates so the analyses of passage and survival were based on data from the rearing groups pooled. Conditions during the December study were more conducive to passing volitionally migrating fish than conditions during the November study. The passage percentage of the fish released in the reservoir was similar between studies (about 70 percent), but the passage occurred in a median of 1.0 day during the December study and a median of 9.3 days during the November study. More than 93 percent of the dam passage of volitionally migrating fish occurred at night during each study. This finding corroborates results of previous studies at Cougar Dam and suggests that the operating conditions at night are most important to volitionally migrating fish, given the current configuration of the dam. Most fish released near the temperature control tower passed through the RO. A total of 92.2 percent of the treatment group passed through the RO during the November study and the RO was the only route open during the December study. The assumptions of the survival model were either met or adjusted for during each study. There was little evidence that tagger skill or premature failure of radio transmitters had an effect on survival estimates. There were statistically significant differences in travel times between treatment and control groups through several of the river reaches they had in common, but the differences were typically only a few hours, and the two groups likely experienced the same in-river conditions. There was direct evidence of bias due to detection of euthanized fish with live transmitters released as part of the study design. The bias was ameliorated by adjusting the survival estimates for the probability of detecting dead fish with live transmitters, which reduced the estimated survival probabilities by about 0.02. The data and models indicated that the treatment effect was not fully expressed until the study reach terminating with Marshall Island Park on the Willamette River, a distance of 105.8 kilometers downstream of Cougar Dam. This was the first reach in which the 95-percent confidence interval of the estimated reach-specific relative survival overlapped 1.0, indicating similar survival of treatment and control groups. The median travel time of the treatment group from release to Marshall Island Park was 1.64 days during the November study and 1.36 days during the December study. The survival probability of fish that passed into the RO was greater during the December study than during the November study. The relative survival probability of fish passing through the RO was 0.4594 (standard error [SE] 0.0543) during the November study and 0.7389 (SE 0.1160) during the December study. These estimates represent relative survival probabilities from release near Cougar Dam to the Marshall Island site. The estimated survival probability of RO passage was lower than previous studies based on balloon and PIT tags, but higher than a similar study based on radio transmitters. We suggest that, apart from dam operations, the differences in survival primarily are due to the release location. We hypothesize that the balloon- and PIT-tagged fish released through a hose at a point near the RO gate opening experienced more benign conditions than the radio-tagged fish passing the RO volitionally. This hypothesis could be tested with further study. An alternative hypothesis is that some live fish remained within the study area beyond the life of their radio transmitter. The results from these and previous studies indicate that entrainment and survival of juvenile salmonids passing Cougar Dam varies with dam operating conditions. The condition most conducive to dam passage has been the discharge and low pool elevation condition tested during December 2012. That condition included large RO gate openings and was the condition with the highest dam passage survival.

Oregon↗
USGS2014

Methow River Studies, Washington: abundance estimates from Beaver Creek and the Chewuch River screw trap, methodology testing in the Whitefish Island side channel, and survival and detection estimates from hatchery fish releases, 2013

Salmon and steelhead populations have been severely depleted in the Columbia River from factors such as the presence of tributary dams, unscreened irrigation diversions, and habitat degradation from logging, mining, grazing, and others (Raymond, 1988). The U.S. Geological Survey (USGS) has been funded by the Bureau of Reclamation (Reclamation) to provide evaluation of on-going Reclamation funded efforts to recover Endangered Species Act (ESA) listed anadromous salmonid populations in the Methow River watershed, a watershed of the Columbia River in the Upper Columbia River Basin, in north-central Washington State (fig. 1). This monitoring and evaluation program was funded to document Reclamation’s effort to partially fulfill the 2008 Federal Columbia River Power System Biological Opinion (BiOp) (National Oceanographic and Atmospheric Administration, Fisheries Division 2003). This Biological Opinion includes Reasonable and Prudent Alternatives (RPA) to protect listed salmon and steelhead across their life cycle. Species of concern in the Methow River include Upper Columbia River (UCR) spring Chinook salmon ( Oncorhynchus tshawytscha ), UCR summer steelhead ( O. mykiss ), and bull trout ( Salvelinus confluentus ), which are all listed as threatened or endangered under the ESA. The work done by the USGS since 2004 has encompassed three phases of work. The first phase started in 2004 and continued through 2012. This first phase involved the evaluation of stream colonization and fish production in Beaver Creek following the modification of several water diversions (2000–2006) that were acting as barriers to upstream fish movement. Products to date from this work include: Ruttenburg (2007), Connolly and others (2008), Martens and Connolly (2008), Connolly (2010), Connolly and others (2010), Martens and Connolly (2010), Benjamin and others (2012), Romine and others (2013a), Weigel and others (2013a, 2013b, 2013c), and Martens and others (2014). The second phase, initiated in 2008, focuses on the evaluation of the M2 reach (rkm 66– 80) of the mainstem Methow River prior to restoration actions planned by Reclamation and Yakama Nation. The M2 study was designed to help understand the inter-relationships between stream habitat and the life history of various fish species to explain potential success or limitations in response to restoration actions. To help document changes derived by restoration, two reference reaches (Upper Methow between rkm 85 and 90, and Chewuch River between rkm 4 and 11) were identified based on relative lack of disturbance, proximity to the restoration reach, and relative unconfined geomorphology. A control reach (Lower Methow between rkm 57 and 64, also referred to as “Silver Reach”) was 2 identified based on its similar disturbance as the reference reach, proximity to the restoration reach, and relatively unconfined geomorphology. Products to date include Barber and others (2011), Bellmore (2011), Tibbits and others (2012), Bellmore and others (2013), Benjamin and others (2013), Romine and others (2013b), Bellmore and other (2014), Martens and others (2014), and Martens and Connolly (2014). The third phase of work has been to help with the development and to provide data for modeling efforts. Most of the planned M2 reach restoration is focused on the creation or improvement of offchannel habitat, especially side channels. The pre-restoration portion of this study has been documented by Martens and Connolly (2014). Side channel restoration actions were initiated in 2012 (Whitefish Island side channel, also referred to as SC3; rkm 76) and are planned to continue over the next several years. The Whitefish Island side channel was modified to maintain hydrological connection with the mainstem throughout the year. In addition, several log structures were installed and pools were deepened to create fish habitat. Prior to restoration, this side channel would lose hydrological connection with the mainstem Methow River, leaving one large pool near the bottom of the side channel and several shallow isolated pools that may or may not go dry. In seasonally connected side channels, juvenile salmonid survival in pools less than 100 cm average depth was lower than in pools greater than 100 cm average depth (Martens and Connolly, 2014). In this report, we document our field work and analysis completed in 2013. During 2013, USGS sampling efforts were focused on resampling of three reaches in Beaver Creek, testing methodology in the Whitefish Island side channel, conducting hatchery survival estimates, and operating a screw trap on the Chewuch River (funded by Yakama Nation; fig. 1). The Beaver Creek sampling effort was a revisit of three index sites sampled continuously from 2004 to 2007 to look at the fish response to barrier removal. Methodology testing in Whitefish Island side channel was done to determine the best method for evaluating fish populations after restoration efforts in side channels (previous sampling methods were determined to be ineffective after pools were deepened). Hatchery survival estimates were completed to monitor fish survival in the Methow and Columbia Rivers, while the screw trap was operated to estimate migrating fish populations in the Chewuch River and track passive integrated transponder (PIT)-tagged fish. In addition, we maintained a network of PIT-tag interrogation systems (PTIS), assisted Reclamation with fish removal events associated with stream restoration (two people for 9 days; 14 percent of summer field season), and conducted a stream metabolism study designed to help parameterize and calibrate the stream productivity model (Bellmore and others, 2014) with model validation.

Washington↗
USGS2015

Geomorphic mapping to support river restoration on the Trinity River downstream from Lewiston Dam, California, 1980-2011

Historic land use, dam construction, water storage, and flow diversions in the Trinity River watershed have resulted in downstream geomorphic change, loss of salmonid habitat, and declines in salmonid populations. The USGS in cooperation with the Trinity River Restoration Program, a multi-agency partnership tasked with implementing federally mandated restoration, completed a geomorphic change assessment to inform the planning process for future restoration work. This report documents an ARCMAP geodatabase (v.10.0) containing geomorphic features digitized from a series of rectified orthophotographs ( http://dx.doi.org/10.5066/F7TT4P04 ). Upland, riparian, and channel features were digitized from six available base images (1980, 1997, 2001, 2006, 2009, and 2011). This report describes the structure of the geodatabase and the methods used to delineate individual geomorphic features.

California↗
USGS2015

In-reservoir behavior, dam passage, and downstream migration of juvenile Chinook salmon and juvenile steelhead from Detroit Reservoir and Dam to Portland, Oregon, February 2013-February 2014

In the second year of 2 years of study, the movements of juvenile spring Chinook salmon ( Oncorhynchus tshawytscha ) and juvenile summer steelhead ( Oncorhynchus mykiss ) through Detroit Reservoir, passing Detroit Dam, and migrating downstream to Portland, Oregon, were studied during a 1-year-long period beginning in February 2013. The primary purpose of the study was to provide empirical data to inform decisions about future alternatives for improving downstream passage of salmonids at Detroit Dam. A secondary purpose was to design and assess the performance of a system to detect juvenile salmonids implanted with acoustic transmitters migrating in the Willamette River. Inferences about fish migration were made from detections of juvenile fish of hatchery origin at least 95 millimeters in fork length surgically implanted with an acoustic transmitter and released during the spring (March–May) and fall (September–November) of 2013. Detection sites were placed throughout the reservoir, near the dam, and at two sites in the North Santiam River and at three sites in the Willamette River culminating at Portland, Oregon. We based most inferences on an analysis period up to the 90th percentile of tag life (68–78 days after release, depending on species and season), although a small number of fish passed after that period as late as April 8, 2014. Chinook salmon migrated from the tributaries of release to the reservoir in greater proportion than steelhead, particularly in the fall. The in-reservoir migration behaviors and dam passage of the two species were similar during the spring study, but during the fall study, few steelhead reached the reservoir and none passed the dam within the analysis period. Migrations in the reservoir were directed and non-random, except in the forebay. Depths of fish within 25 meters of the dam were deeper in the day than at night for Chinook salmon and similar in the day and night for steelhead; steelhead generally were at shallower depths than Chinook salmon. The primary factors affecting dam passage rates were seasonal dam operating conditions and diel period. Fish passage rates were much greater during the spring and summer than in the fall and winter, and the difference was attributed to the availability and use of the spillway near the top of the dam during the spring and summer. The flood-control purpose of the reservoir prevented spillway use during much of the fall and winter because of the low forebay elevation. Passage rates at night were greater than in the day during spring and summer (4.2 times) and during the fall and winter (14.9 times). Fish length, dam discharge, and forebay elevation also affected dam passage rates. Travel times from Detroit Dam passage to the downstream sites were shorter during the fall and winter than during the spring and summer, and were less than a median of 8.68 days to Portland. The estimated survival in the 11 kilometers (km) between Detroit Dam and the Minto Dam forebay was lower than in the remaining 241 km to the Portland site. Estimated survival per 100 km in the free-flowing reach from Minto Dam to Portland was 0.675–0.836, depending on species and season, and was similar to other free-flowing rivers in the Western United States. The high probability of fish in the reservoir reaching the dam, the chance for repeated presence near the dam, the fish depths, and the factors known to affect passage rates suggest that a properly designed surface passage route could be a viable downstream passage alternative for juvenile Chinook salmon and steelhead at Detroit Dam. As part of the evaluations conducted at Detroit Dam, we continued to refine and improve methods for monitoring fish movements in the Willamette River. The goal was to develop stable, cost-effective, long-term monitoring arrays suitable for detection of any Juvenile Salmon Acoustic Telemetry System (JSATS)-tagged fish in the Willamette River. These data then could be used to estimate timing, migration rates, and survival of JSATS-tagged fish from various studies in the Willamette River Basin. The challenge, however, is that acoustic telemetry generally performs poorly in shallow, turbulent water, like that found in the Willamette River. We successfully designed, deployed, and maintained a series of monitoring sites near the Oregon cities of Salem, Wilsonville, and Portland. In the spring, detection probabilities at these sites ranged from 0.900 to 1.000. In the fall, the detection probabilities decreased and ranged from 0.526 to 1.000. The lower detection probabilities, particularly at the Salem site (0.526), were owing to loss of data caused by abnormally high flows as well as the 2013 Federal government shutdown, which prevented us from servicing the equipment. The monitoring sites that we installed seem to be robust and enable the efficient use of acoustic-tagged fish for studies of migration or survival in the Willamette River and similar environments.

Oregon↗
USGS2016

Evaluation of the hydraulic and biological performance of the portable floating fish collector at Cougar Reservoir and Dam, Oregon, 2014

The biological and hydraulic performance of a new portable floating fish collector (PFFC) located in a cul-de-sac within the forebay of Cougar Dam, Oregon, was evaluated during 2014. The purpose of the PFFC was to explore surface collection as a means to capture juvenile salmonids at one or more sites using a small, cost-effective, pilot-scale device. The PFFC used internal pumps to draw attraction flow over an inclined plane about 3 meters (m) deep, through a flume at a design velocity of as much as 6 feet per second (ft/s), and to empty a small amount of water and any entrained fish into a collection box. Performance of the PFFC was evaluated at 64 cubic feet per second (ft 3 /s) (Low) and 109 ft 3 /s (High) inflow rates alternated using a randomized-block schedule from May 27 to December 16, 2014. The evaluation of the biological performance was based on trap catch; behaviors, locations, and collection of juvenile Chinook salmon ( Oncorhynchus tshawytscha ) tagged with acoustic transmitters plus passive integrated transponder (PIT) tags; collection of juvenile Chinook salmon implanted with only PIT tags; and untagged fish monitored near and within the PFFC using acoustic cameras. The evaluation of hydraulic performance was based on measurements of water velocity and direction of flow in the PFFC. The PFFC collected 156 juvenile Chinook salmon and 280 individuals of other species, primarily dace (Cyprinidae) and largemouth bass ( Micropterus salmoides ). The collection included one of the 212 acoustic+PIT-tagged fish detected near the PFFC and two of the 1,505 PIT-tagged fish released near the head of the reservoir. No juvenile salmonids were collected between early July and early September when water temperatures near the water surface were greater than about 16 degrees Celsius (°C). Depths of acoustic+PIT-tagged fish indicated a preferential selection of water temperature of 13–15 °C, which was often deeper than the entrance to the PFFC, and those fish rarely were at depths with water temperatures greater than 16 °C. Dam passage of acoustic+PIT-tagged fish was similar to previous years, but much of the passage occurred prior to the date the PFFC began operation. Discovery Efficiency, the proportion of acoustic+PIT-tagged fish detected in the cul-de-sac that were within 10 m of the PFFC entrance and 0–6 m deep (the Discovery Zone), was 0.736 during the Low treatment and 0.639 during the High treatment. Entrance Efficiency, the proportion of fish in the Discovery Zone that were collected by the PFFC, was 0.007 during the Low treatment and 0.000 during the High treatment. Fish Collection Efficiency, the proportion of acoustic+PIT-tagged fish collected of those detected in the cul-de-sac, was 0.005 and 0.000 during the Low and High treatments, respectively. The areas of highest use by acoustic+PIT-tagged fish were between the stern of the PFFC and the outlet of the reservoir (a water temperature control tower), with the greatest use being near the tower. Results from untagged fish detected with acoustic cameras indicated that most fish near and within the PFFC were in the 90–250-millimeter length bin and few were less than 60 millimeters long; most fish were present during crepuscular periods; trajectories of fish outside the PFFC were rarely directed toward the entrance; and many fish entering the PFFC swam back out before they could be collected. The hydraulic performance of the PFFC did not achieve the design goals of smooth acceleration of inflow culminating in a peak water velocity of 6 ft/s and, as a result, the hydraulic performance likely contributed to the low biological performance. The greatest water velocity measured in the PFFC (1.87 ft/s) was lower than designed due at least in part to the PFFC being lower in the water column than expected. Additionally, difficulties during anchor deployment prevented placement of the PFFC as near to the reservoir outlet as planned, resulting in a PFFC position outside the prevailing flow field and known areas of high fish densities. Overall, the results indicate that location, hydraulic conditions, water temperature, and shallow depth of the entrance were among the factors contributing to the low biological performance of the PFFC in 2014.

Oregon↗
USGS2018

Passage survival of juvenile steelhead, coho salmon, and Chinook salmon in Lake Scanewa and at Cowlitz Falls Dam, Cowlitz River, Washington, 2010–16

A multi-year evaluation was conducted during 2010–16 to evaluate passage survival of juvenile steelhead ( Oncorhynchus mykiss ), Chinook salmon ( O. tshawytscha ), and coho salmon ( O. kisutch ) in Lake Scanewa, and at Cowlitz Falls Dam in the upper Cowlitz River Basin, Washington. Reservoir passage survival was evaluated in 2010, 2011, and 2016, and included the tagging and release of 1,127 juvenile salmonids. Tagged fish were released directly into the Cowlitz and Cispus Rivers, 22.3 and 8.9 km, respectively, upstream of the reservoir, and were monitored as they moved downstream into, and through the reservoir. A single release-recapture survival model was used to analyze detection records and estimate reservoir passage survival, which was defined as successful passage from reservoir entry to arrival at Cowlitz Falls Dam. Tagged fish generally moved quickly downstream of the release sites and, on average, arrived in the dam forebay within 2 d of release. Median travel time from release to first detection at the dam ranged from 0.23 to 0.96 d for juvenile steelhead, from 0.15 to 1.11 d for juvenile coho salmon, and from 0.18 to 1.89 d for juvenile Chinook salmon. Minimum reservoir passage survival probabilities were 0.960 for steelhead, 0.855 for coho salmon and 0.900 for Chinook salmon. Dam passage survival was evaluated at the pilot-study level during 2013–16 and included the tagging and release of 2,512 juvenile salmonids. Juvenile Chinook salmon were evaluated during 2013–14, and juvenile steelhead and coho salmon were evaluated during 2015–16. A paired-release study design was used that included release sites located upstream and downstream of Cowlitz Falls Dam. The downstream release site was positioned at the downstream margin of the dam’s tailrace, which allowed dam passage survival to be measured in a manner that included mortality that occurred in the passage route and in the dam tailrace. More than one-half of the tagged Chinook salmon (52 percent) released upstream of Cowlitz Falls Dam moved downstream and passed the project; the remaining fish either remained upstream of the dam (37 percent) or were collected (11 percent). In 2015 and 2016, collection efficiencies at Cowlitz Falls Dam were abnormally high for juvenile steelhead and coho salmon, which resulted in few fish passing the dam. Seven percent of the tagged steelhead (40 fish) and 4 percent of the tagged coho salmon (18 fish) released upstream of the dam eventually passed the project, but these low numbers of fish precluded the estimation of meaningful survival estimates. Dam passage survival probability estimates for juvenile Chinook salmon were 0.828 in 2013 and 0.861 in 2014, lower than previously reported for turbine-specific passage Cowlitz Falls Dam.

Washington↗
USGS2018

Fish behavior and abundance monitoring near a floating surface collector in North Fork Reservoir, Clackamas River, Oregon, using multi-beam acoustic imaging sonar

An imaging sonar was used to assess the behavior and abundance of fish sized the same as salmonid smolt and bull trout ( Salvelinus confluentus ) at the entrance to the juvenile fish floating surface collector (FSC) at North Fork Reservoir, Oregon. The purpose of the FSC is to collect downriver migrating juvenile salmonids (Chinook salmon [ Oncorhynchus tshawytscha ], Coho salmon [ Oncorhynchus kisutch ], and steelhead [ Oncorhynchus mykiss ]) at the North Fork Dam and to safely route them around the hydroelectric projects. The objective of the imaging sonar component of this study was to assess the behaviors of both smolt and predator-size fish (smolt [60–250 millimeter] and predator 350–650 [millimeter]) observed near the FSC and to determine if the presence of predator-size fish influenced the abundance of smolt-size fish. An imaging sonar was deployed near the entrance to the FSC during the spring smolt out-migration period. The imaging sonar technology was an informative tool for assessing abundance and spatial and temporal behaviors of both smolt and predator-size fish near the entrance of the FSC. Both smolt and predator-size fish were regularly observed near the entrance, with greater abundances observed during day than during night. Behavioral differences were also observed between the two fish-size classes, with smolt-size fish traveling straighter with more directed movement, and predator-size fish generally showing more milling behavior. Additionally, the presence of predator-size fish may be effecting the abundance and direction of travel of smolt-size fish, as counts of smolt-size fish were reduced in conjunction with the presence of predator-size fish and a greater proportion of smolt-size fish were observed traveling away from the FSC when predator-size fish were present than when predator-size fish were absent. Results of modeling potential predator-prey interactions and influences indicated that both the number of juvenile fish tracks and photoperiod had the strongest effects on the number of predator fish tracks, with more predator-size fish tracks observed as the number of smolt-size fish tracks increased. Overall, the results indicate that predator-size fish are present near the entrance of the FSC, concomitant with smolt-size fish, and their abundances and behaviors indicate that they may be drawn to the entrance of the FSC because of the abundance of prey-sized fish found there.

Oregon↗
USGS2018

Development of new information to inform fish passage decisions at the Yale and Merwin hydro projects on the Lewis River, Washington—Final report, 2018

The reintroduction of extirpated salmonids to historically occupied areas is becoming increasingly common as a conservation and recovery strategy. Often, reintroductions are implemented after the factors that originally led to species extirpation have been reduced, eliminated, or mitigated. For anadromous Oncorhynchus spp. (Pacific salmon) and O. mykiss (steelhead), addressing barriers to migration, which have been a primary factor in the decline and extirpation of many populations, has been an integral component of recovery efforts. Mitigation has included barrier removal, developing fish passage opportunities, and (or) actively trapping and hauling juvenile and adult anadromous salmonids around barriers. With any reintroduction, there are a number of concerns regarding the ecological impact of the reintroduction efforts. Three of the main tenets to consider when assessing reintroductions are (1) the potential benefits if reintroduction is successful, (2) the biological risk through interactions of reintroduced strains with existing populations, and (3) the factors potentially limiting a successful reintroduction. This report focuses on information and data to address the second and third factors as they apply to the upper Lewis River in Washington. The upper Lewis River historically contained wild populations of O. tshawytscha (Chinook salmon), O. kisutch (coho salmon), and steelhead. These populations were extirpated after completion of hydropower facilities on Lake Merwin in 1932, Yale Lake in 1953, and Swift Reservoir in 1958, which prevented fish from migrating to and from ocean environments. However, recent licenses issued by the Federal Energy Regulatory Commission require the installation and operation of an upstream fish passage facility at Lake Merwin and a downstream fish passage facility at Swift Reservoir. The licenses were developed in consultation with the National Marine Fisheries Service and the U.S. Fish and Wildlife Service. The overarching goal of this fish reintroduction project is to establish viable, self-sustaining, naturally reproducing, harvestable populations of spring Chinook salmon, winter steelhead, and coho salmon at levels higher than minimum viable populations. This report uses a combination of field data and existing information to address six key objectives related to the reintroduction in order to inform decisions about passage at the Yale Lake and Lake Merwin hydropower projects. The objectives are (1) a review of information relevant to anadromous fish reintroduction and full fish passage; (2) a habitat assessment of tributaries to Swift Reservoir, Yale Lake, and Lake Merwin; (3) a field study to assess adult potential for spawning success; (4) an assessment of juvenile production and outmigration success; (5) a Lake Merwin predator impact study; and (6) a set of studies assessing interactions between anadromous and resident fish.

Washington↗
USGS2019

Fish and habitat assessment in Rock Creek, Klickitat County, Washington 2016–17

Executive Summary Intermittent streams are important and productive for salmonid habitat. Rock Creek, in southeastern Washington, flows south to the Columbia River at river kilometer (rkm) 368 and is an intermittent stream of great significance to the Yakama Nation and to the Kah-miltpah (Rock Creek) Band in particular. Historically, native steelhead (anadromous form of rainbow trout [ Oncorhynchus mykiss ]) and bridgelip sucker ( Catostomus columbianus ) populations were used by the Kah-miltpah Band for sustenance, trade, and traditional practices. Anadromous salmonid populations currently present and being monitored in the Rock Creek subbasin include Coho ( O. kisutch ) salmon and steelhead. Resident rainbow trout are also present and monitored (rainbow trout and steelhead will be collectively referred to as O. mykiss throughout this report). Streamflow is a limiting habitat factor in this system, but despite this, steelhead and Coho salmon still successfully return to spawn, rear, out-migrate, and survive over-summer in many of the isolated pools. We completed habitat surveys during 2015–17 to assess the perennial pools during low-flow conditions. The lower river sections (rkm 2–13) had proportionately more dry sections than the upper river sections (rkm 14–22) for all years surveyed and had higher variability among habitat types across years. The surveyed dry sections within the lower river ranged from 44 to 57 percent, with 2015 (a drought year) as the highest and 2017 the lowest. The percentage of pool habitat in the lower river was 21−24 percent, with 2015 as the lowest and 2016 and 2017 both at 24 percent. The upper river sections had a relatively high percentage of non-pool wet habitat (49−51 percent), followed by dry (33−36 percent) and pool habitat (17−18 percent). In Walaluuks Creek, the percentage of pool habitat was the most consistent across the years, ranging from 10 to 13 percent.

Washington↗
USGS2021

Sediment mobility and river corridor assessment for a 140-kilometer segment of the main-stem Klamath River below Iron Gate Dam, California

This river corridor assessment documents sediment mobility and river response to flood disturbance along a 140-kilometer segment of the main-stem Klamath River below Iron Gate Dam, California. Field and remote sensing methods were used to assess fundamental indicators of active sediment transport and river response to a combination of natural runoff events and reservoir releases during the study period from 2005 to 2019. Discharge measurements at two gaged sites and bed-material samples at two ungaged sites provided direct and indirect evidence of mobile bed conditions, scour and fill, and surface flushing of fine sediment. Available remote-sensing datasets collected in 2005, 2009, 2010, and 2016 were used to determine sediment storage, flood inundation boundaries, and provide indirect evidence of flood-induced scour. These datasets validate channel-maintenance flows defined by Shea and others (2016). During the study period, flows greater than or equal to 6,030 cubic feet per second mobilized the substrate, caused localized scour, and flushed fine sediment from bar surfaces. Flows greater than or equal to 10,400 cubic feet per second stripped vegetation from bars and floodplains and produced deeper scour. Flood disturbance within the study reach is produced by the combined effect of natural flows and reservoir releases, which resulted in mobile bed conditions during the study period. Periodic scour and substrate disturbance are considered by the U.S. Fish and Wildlife Service to be integral for managing disease-induced mortality of juvenile and adult salmonids. Substrate conditions conducive to parasites that host infectious diseases, particularly Ceratonova shasta, occur periodically. Additional studies are required to determine whether disease prevalence can be mitigated by well-timed reservoir releases. Study results are useful for interpreting linkages among physical and biological processes and for evaluating the effectiveness of flow management targeted to improve river bed conditions for endangered salmonid populations.

California↗
USGS2022

Evaluation of fish behavior at the entrances to a Selective Water Withdrawal structure in Lake Billy Chinook, Oregon, 2021

Imaging sonar was used to assess the behavior, abundance, and timing of fish at the entrances to the Selective Water Withdrawal (SWW) intake structure located in the forebay of Round Butte Dam, Oregon during the spring of 2021. The purposes of the SWW are (1) to direct surface currents in the forebay to attract and collect downriver migrating juvenile salmonid smolts (Chinook salmon [ Oncorhynchus tshawytscha ], sockeye salmon [ O. nerka ], and steelhead [ O. mykiss ]) from Lake Billy Chinook and (2) to enable operators of the SWW to withdraw water from surface and benthic elevations in the reservoir to manage downriver water temperatures. Part of the evaluation, to determine how well the structure performs at collecting juvenile salmonids, needs (A) to regularly assess how fish are approaching the entrance, and (B) to determine if operational flows could be optimized to increase the attraction of smolts present in the forebay of Lake Billy Chinook. The primary goals of this study were (1) to assess the abundance and behaviors of smolt-size fish observed near the SWW and (2) to provide data of the effect of two-night generation operation timing conditions on movements and behaviors of fish near the entrance to the SWW structure. The purpose of this assessment is to improve downstream passage solutions. Two imaging sonar units were deployed during the spring 2021 smolt out-migration period. One unit monitored fish movements near the south entrance and one unit monitored movements near the north entrance of the SWW. Both smolt and bull trout ( Salvelinus confluentus )-size fish were regularly observed near the entrances with greater abundances observed during night, corresponding with greater discharge through the SWW than during the day when discharge was reduced. Differences in fish abundance were observed between the night generation operation timing conditions, with increased fish counts observed when elevated discharge was extended to 6:00 a.m., rather than when discharges have been traditionally reduced in the early morning at 4:00 a.m. Fish of all size groups were primarily observed near the center of the SWW, and greater abundances of fish were observed at the south entrance. Increased counts of bull trout-size fish coincided with the increased abundances of smolt-size fish. Overall, the results indicate that (A) smolt-size fish were more abundant near the entrance of the SWW during periods of increased discharge, (B) bull trout-size fish were present at the SWW, and (C) fish were more numerous at the SWW when night generation operation timing was extended later into the morning hours rather than the traditional operation timing flow reduction.

Oregon↗
USGS2023

Applying intrinsic potential models to evaluate salmon (Oncorhynchus spp.) introduction into main-stem and tributary habitats upstream from the Skagit River Hydroelectric Project, northern Washington

We assessed habitat suitability for salmonids across selected tributaries upstream from three hydroelectric dams on the upper Skagit River in Whatcom County, northern Washington. We used NetMap, a commercial toolset within the ArcMap geographic information system (GIS), to analyze stream attributes based upon a synthetic stream channel network derived from digital elevation models. The GIS-derived stream attributes—including gradient, bankfull width, valley width index, elevation, and stream flow—allowed us to examine the spatial distribution and relative quality of spawning and rearing habitat for salmonids based on existing intrinsic potential (IP) models. As a first step, we created maps of potential anadromous fish distribution by identifying potential migration barriers within the synthetic stream network. Next, we applied a suite of existing IP models for steelhead, coho, and Chinook salmon ( Oncorhynchus mykiss , O. kisutch , and O. tshawytscha , respectively) to estimate low, medium, and high IP habitat for each species. Three different IP models were used for each species, based on species preference curves from populations from coastal Oregon, northern California, Alaska, and western Washington. We found that at least 25 tributaries that were greater than third order and contained habitat with the potential for anadromous fish, totaling about 470 river kilometers in 4,453 synthetic stream reaches averaging about 100 meters (m) in length. The IP of each of these reaches was calculated and placed into low, medium, and high IP categories. For Chinook salmon, the only stream with significantly (in other words, greater than 1 kilometer [km]) high IP reaches was the upper Skagit River upstream from Ross Lake reservoir in Canada, upstream from the third dam in the hydroelectric system. There were differences among the three models evaluated, with the model derived for the lower Skagit River showing more high and medium IP habitat than the other two models that were designed for the Columbia River Basin. For coho salmon, all three models showed similar results favoring medium IP over low and high IP habitat. Of the 3 species examined with existing IP models, steelhead had the most habitat rated as high IP with 19 targeted tributaries showing greater than 1 km of high intrinsic potential habitat.

Washington↗
USGS2008

Effects of urbanization on stream ecosystems in the Willamette River basin and surrounding area, Oregon and Washington

This report describes the effects of urbanization on physical, chemical, and biological characteristics of stream ecosystems in 28 watersheds along a gradient of urbanization in the Willamette River basin and surrounding area, Oregon and Washington, from 2003 through 2005. The study that generated the report is one of several urban-effects studies completed nationally by the U.S. Geological Survey National Water-Quality Assessment Program. Watersheds were selected to minimize natural variability caused by factors such as geology, elevation, and climate, and to maximize coverage of different stages of urban development among watersheds. Because land use or population density alone often are not a complete measure of urbanization, a combination of land use, land cover, infrastructure, and socioeconomic variables were integrated into a multimetric urban intensity index (UII) to represent the degree of urban development in each watershed. Physical characteristics studied include stream hydrology, stream temperature, and habitat; chemical characteristics studied include sulfate, chloride, nutrients, pesticides, dissolved and particulate organic and inorganic carbon, and suspended sediment; and biological characteristics studied include algal, macroinvertebrate, and fish assemblages. Semipermeable membrane devices, passive samplers that concentrate trace levels of hydrophobic organic contaminants such as polycyclic aromatic hydrocarbons and polychlorinated biphenyls, also were used. The objectives of the study were to (1) examine physical, chemical, and biological responses along the gradient of urbanization and (2) determine the major physical, chemical, and landscape variables affecting the structure of aquatic communities. Common effects documented in the literature of urbanization on instream physical, chemical, and biological characteristics, such as increased contaminants, increased streamflow flashiness, increased concentrations of chemicals, and changes in aquatic community structure toward a more tolerant community associated with organically enriched conditions, generally were observed in this study. The strongest correlations to the UII and to many of the algal, macroinvertebrate, and fish assemblage metrics and community ordination involved water-chemistry metrics including the total pesticide concentration, toxic equivalents (extract assay from semipermeable membrane devices), and dissolved oxygen. Hydrologic variability metrics, such as flashiness, that normally are considered to be one of the main processes of urban disturbance had a strong association to the algal and fish assemblages in this study; however, the hydrologic variables for macroinvertebrates were secondary to the water-chemistry metrics mentioned above. Generally, the high urban intensity sites had high abundances of eutrophic and lower dissolved oxygen-indicating diatoms, high abundances of noninsects and tolerant insects, and high abundances of nonnative fish species. On the other hand, the low urban intensity sites had higher abundances of pollution sensitive diatoms, larger numbers of the sensitive macroinvertebrate EPT taxa (Ephemeroptera, Plecoptera and Trichoptera Orders), and fish assemblages with higher abundances of sensitive salmonids. The percent salmonid and macroinvertebrate EPT richness metrics plotted against the UII indicated a possible threshold response at about 25 on the UII, which is equivalent to an impervious surface value of about 5 percent. However, due to the added agricultural land use at sites within the 25 to 60 UII range, this possible threshold probably is not solely due to urbanization, but a combination of urban and agricultural land use. The effects of agricultural and urban land use could not be distinguished from each other, yet combined they provide a good assessment of overall watershed disturbance.

Oregon, Washington↗
USGS2010

Development of an Environmental Flow Framework for the McKenzie River Basin, Oregon

The McKenzie River is a tributary to the Willamette River in northwestern Oregon. The McKenzie River is approximately 90 miles in length and has a drainage area of approximately 1,300 square miles. Two major flood control dams, a hydropower dam complex, and two hydropower canals significantly alter streamflows in the river. The structures reduce the magnitude and frequency of large and small floods while increasing the annual 7-day minimum streamflows. Stream temperatures also have been altered by the dams and other anthropogenic factors, such as the removal of riparian vegetation and channel simplification. Flow releases from one of the flood control dams are cooler in the summer and warmer in the fall in comparison to unregulated flow conditions before the dam was constructed. In 2006, the Oregon Department of Environmental Quality listed a total of 112.4, 6.3, and 55.7 miles of the McKenzie River basin mainstem and tributary stream reaches as thermally impaired for salmonid rearing, salmonid spawning, and bull trout, respectively. The analyses in this report, along with previous studies, indicate that dams have altered downstream channel morphology and ecologic communities. In addition to reducing the magnitude and frequency of floods, dams have diminished sediment transport by trapping bed material. Other anthropogenic factors, such as bank stabilization, highway construction, and reductions of in-channel wood, also have contributed to the loss of riparian habitat. A comparison of aerial photography taken in 1939 and 2005 showed substantial decreases in secondary channels, gravel bars, and channel sinuosity, particularly along the lower alluvial reaches of the McKenzie River. In addition, bed armoring and incision may contribute to habitat degradation, although further study is needed to determine the extent of these processes. Peak streamflow reduction has led to vegetation colonization and stabilization of formerly active bar surfaces. The large flood control dams on Blue River and South Fork McKenzie River likely have had the greatest effect on downstream habitats because these sediment and flood-rich tributaries historically contributed a disproportionate volume of bed material, wood, and peak flows in comparison with the spring-fed tributaries of the upper McKenzie River basin. The ecological effects of the dams were examined by focusing on nine exemplar aquatic and terrestrial species, including spring Chinook salmon, bull trout, Oregon chub, Pacific and western brook lamprey, red-legged frog, western pond turtle, alder, and cottonwood. The changes caused by the dams to streamflow hydrograph affect all these and other species in complex ways, although a few commonalities are apparent. A loss of channel complexity in the McKenzie River basin, which is associated with the reduction in flood events and widespread channel stabilization, is the primary factor related to the observed population declines for all nine exemplar species. The dams also have caused direct ecological effects by blocking access to habitat, changing the amount and timing of available critical habitat, and changing water temperature during important seasons for different life stages.

Scientific Investigations Report↗
USGS2011

Crims Island-Restoration and monitoring of juvenile salmon rearing habitat in the Columbia River Estuary, Oregon, 2004-10

Under the 2004 Biological Opinion for operation of the Federal Columbia River Power System released by the National Marine Fisheries Service, the U.S. Army Corps of Engineers (USACE), the Bonneville Power Administration (BPA), and the Bureau of Reclamation (Reclamation) were directed to restore more than 4,047 hectares (10,000 acres) of tidal marsh in the Columbia River estuary by 2010. Restoration of Crims Island near Longview, Washington, restored 38.1 hectares of marsh and swamp in the tidal freshwater portion of the lower Columbia River. The goal of the restoration was to improve habitat for juveniles of Endangered Species Act (ESA)-listed salmon stocks and ESA-listed Columbian white-tailed deer. The U.S. Geological Survey (USGS) monitored and evaluated the fisheries and aquatic resources at Crims Island in 2004 prior to restoration (pre-restoration), which began in August 2004, and then post-restoration from 2006 to 2009. This report summarizes pre- and post-restoration monitoring data used by the USGS to evaluate project success. We evaluated project success by examining the interaction between juvenile salmon and a suite of broader ecological measures including sediments, plants, and invertebrates and their response to large-scale habitat alteration. The restoration action at Crims Island from August 2004 to September 2005 was to excavate a 0.6-meter layer of soil and dig channels in the interior of the island to remove reed canary grass and increase habitat area and tidal exchange. The excavation created 34.4 hectares of tidal emergent marsh where none previously existed and 3.7 hectares of intertidal and subtidal channels. Cattle that had grazed the island for more than 50 years were relocated. Soil excavated from the site was deposited in upland areas next to the tidal marsh to establish an upland forest. Excavation deepened and widened an existing T-shaped channel to increase tidal flow to the interior of the island. The western arm of the existing 'T-channel' was extended westward and connected to Bradbury Slough to create a second outlet to the main river. New intertidal channels were constructed from the existing 'T-channel' and tidal mudflats became inundated at high tide to increase rearing habitat for juvenile salmonids. The restoration action resulted in a 95-percent increase in available juvenile salmon rearing habitat. We collected juvenile salmon and other fishes at Crims Island and a nearby reference site using beach seines and fyke nets annually from March through August during all years. Benthic invertebrates were collected with sediment corers and drift invertebrates were collected with neuston nets. Juvenile salmon stomach contents were sampled using lavage. Vegetation and sediments characteristics were surveyed and we conducted a topographic/bathymetric survey using a RTK (real time kinematic) GPS (global positioning system). The fish assemblage at Crims Island, composed primarily of threespine stickleback (Gasterosteus aculeatus), non-native banded killifish (Fundulus diaphanus), peamouth chub (Mylocheilus caurinus), subyearling Chinook salmon (Oncorhynchus tshawytscha) (hereinafter referred to as subyearlings), and small numbers of juvenile chum salmon (Oncorhynchus keta), did not differ appreciably pre- and post-restoration. Subyearlings were the primary salmonid collected and were seasonally abundant from April through May during all years. The abundance of juvenile salmon declined seasonally as water temperature exceeded 20 degrees C in the Reference site by mid-June; however, subyearlings persisted at the Mainstem site and in subtidal channels of the Restoration site through the summer in water temperatures exceeding 22 degrees C. Residence times of subyearlings in Crims Island backwaters generally were short consisting of one or two tidal cycles. Median residence time was longer in the Restoration site than in the Reference site pre- and post-restoration. Small (mean = 55.7 millimeters) subyea

Scientific Investigations Report↗
USGS2011

River-aquifer exchanges in the Yakima River basin, Washington

Five categories of data are analyzed to enhance understanding of river-aquifer exchanges-the processes by which water moves between stream channels and the adjacent groundwater system-in the Yakima River basin. The five datasets include (1) results of chemical analyses of water for tritium (3H, a radioactive isotope of hydrogen) and the ratios of the stable isotopes of hydrogen (2H/1H) and oxygen (18O/16O), (2) series of stream discharge measurements within specified reaches (seepage investigations or 'runs'), (3) vertical hydraulic gradients (between stream stage and hydraulic heads the underlying aquifer) measured using mini-piezometers, (4) groundwater levels and water temperature in shallow wells near stream channels, and (5) thermal profiles (continuous records of water temperature along river reaches). Exchanges are described in terms of streamflow, vertical hydraulic gradients, groundwater temperature and levels, and streamflow temperature, and where appropriate, the exchanges are discussed in terms of their relevance to and influence on salmonid habitat. The isotope data shows that the ultimate source of surface and groundwater is meteoric water derived from atmospheric precipitation. Water from deep wells has a different isotopic composition than either shallow groundwater or surface water, indicating that the deep groundwater system contributes, at most, only a small component of the surface-water discharge. The isotope data confirms that river-aquifer exchanges involve primarily modern streamflow and modern, shallow groundwater. Net exchanges of water for 46 stream sections investigated with seepage runs ranged from nearly zero to 1,071 ft3/s for 28 gaining sections, and -3 to -242 ft3/s for 18 losing sections. The magnitude of the upper 50 percent of the net gains is an order of magnitude larger than those for net losses. The sections have a normalized net exchange (as absolute value) that fully ranged from near 0 to 65.6 (ft3/s)/mi. Gaining-section values ranged from about 0.1 to 65.6 (ft3/s)/mi, and losing section values ranged from about -0.1 to -35.4 (ft3/s)/mi. Gains are much more vigorous than the losses with 55 percent being larger than 3.0 (ft3/s)/ mi, whereas, only 6 percent of the negative net exchanges were larger than 3.0 (ft3/s)/mi. Gains and losses for 167 measured reaches within the 46 sections ranged from about 70 to -75 (ft3/s)/mi, and ranged more than 5 orders of magnitude. The median values for the gains and losses were 5.1 and -4.4 (ft3/s)/mi, respectively. The magnitude of the gains was larger than the losses; more than 40 percent of the gains were greater than 10 (ft3/s)/mi, and only about 25 percent of the losses were greater than 10 (ft3/s)/mi. Reaches with large gains are identified and these reaches represent potentially important areas for various life stages of salmonids and possibly for preservation or restoration of that habitat. Ninety-nine measurements of vertical hydraulic gradients (VHGs) were made using mini-piezometers. The median for the measurements was -0.35 ft/ft (negative values indicate downward flow), and in terms of absolute values, the median was 0.05 ft/ft. The VHGs tended to be small. Seventy VHG values were negative (indicating streamflow losses), and 29 were positive (indicating streamflow gains). VHGs vary more than 4 orders of magnitude, and in terms of magnitudes, 65 percent were less than 0.1 ft/ft. The negative VHG values are not only more prevalent but are larger than the positive values. The magnitudes of almost 50 percent of the negative VHGs are greater than 0.05 ft/ft and only 33 percent of the positive VHGs are greater than 0.05 ft/ft. The percentile distribution of the VHG data, which is similar to the shape of the seepage data distribution, shows that beyond the 80th percentile, the positive values become much larger, indicating that the largest VHGs have a different controlling mechanism. The VHGs were formulated in terms of fluxes per unit are

Scientific Investigations Report↗
USGS2012

Quality of water in the White River and Lake Tapps, Pierce County, Washington, May-December 2010

The White River and Lake Tapps are part of a hydropower system completed in 1911–12. The system begins with a diversion dam on the White River that routes a portion of White River water into the southeastern end of Lake Tapps, which functioned as a storage reservoir for power generation. The stored water passed through the hydroelectric facilities at the northwestern end of the lake and returned to the White River through the powerhouse tailrace. Power generation ceased in January 2004, which altered the hydrology of the system by reducing volumes of water diverted out of the river, stored, and released through the powerhouse. This study conducted from May to December 2010 created a set of baseline data collected under a new flow regime for selected reaches of the White River, the White River Canal (Inflow), Lake Tapps Diversion (Tailrace) at the powerhouse, and Lake Tapps. Three sites, one on the White River at Headworks, one on the White River at R Street, and one on the Tailrace, were equipped for continuous recording of water-quality data, and three sites (Headworks, White River Canal Inflow, and Tailrace) were sampled for discrete water-quality data. Nine lake sites were measured for physical and water-quality properties and samples were collected for analyses of nutrients, suspended solids, and fecal-coliform bacteria concentrations. Samples from the lake also were analyzed for concentrations of chlorophyll a and organic chemicals. Discrete samples indicated that water from the White River, White River Canal Inflow, and Tailrace sites generally was turbid, warm, chemically dilute, and well-oxygenated. Exceptions occurred at the sites when flow to the White River Canal was suspended or when little or no flow was released from the lake into the Tailrace. The quality of physical properties and concentrations in water measured continuously at the three sites generally was good and met the freshwater criteria designated by Washington State Department of Ecology for recreational and aquatic-life uses, with several exceptions. The 7-day average of daily maximum temperatures (7–DADMax) was greater than the freshwater aquatic life criterion of 16 degrees Celsius (°C) for core summer salmonid habitat on 6 days at the Headworks site and 37 days at the R-Street site during the study. The 7-DADMax temperatures were greater than the 13°C criterion for spawning, rearing, and incubation on 6 days at the Headworks site and 20 days at the R-Street site. The freshwater aquatic life criterion for dissolved oxygen of 9.5 milligrams per liter (mg/L) for core summer salmonid habitat was not met at the Headworks and R-Street sites for periods during July and August 2010. Exceptions also occurred at the Headworks site for measurements of pH, which were greater than the aquatic life upper limit of 8.5 pH units during July 2010. Aquatic life pH criteria were not met at the Tailrace site during June, July, and August 2010, when pH was greater than 8.5 pH units, and during August 2010 when pH decreased to less than 6.5 pH units. Lake Tapps water near the surface was relatively clear, warm, and well oxygenated. The clearest water of the nine lake sites was at the Deep site with a median Secchi disk transparency measurement of 6.05 m (meters), which represents a two- to six-fold increase over historical measurements of transparency at this location. Median water temperatures were 18.2–18.9°C and maximums were from 22.9–25.0°C. Median dissolved oxygen concentrations were greater than 8.42 mg/L and minimums generally were not lower than 7.4 mg/L. By early July 2010, weak thermal stratification developed at most lake sites into at least a warm surface layer overlying a small thermocline. A well-defined hypolimnion developed below the thermocline only at the Deep site. With the development of thermal stratification, hypolimnion water became anoxic at several sites (Deep, Tapps Island, Snag Island, and Lake Outlet). By late September 2010, an anoxic layer about 15 m thick had formed in the hypolimnion of the Deep site. Mixing during autumn overturn in late November re-oxygenated the water column of all the sites with about 10–12 mg/L of dissolved oxygen. On the basis of pH and specific conductance measurements, Lake Tapps water is pH neutral and chemically dilute. Median pH values for water in the epilimnion and the hypolimnion ranged from 6.84 to 7.64 pH units and maximums did not exceed 7.8 pH units at any site. Median specific conductance was typically less than 70 microsiemens per centimeter at 25°C for the epilimnion and the hypolimnion. Concentrations of nutrients and chlorophyll a in Lake Tapps were low. At most of the sites and in most of the samples from the epilimnion, total phosphorus concentrations were less than the Washington State Department of Ecology phosphorus criterion of 0.01 mg/L for maintaining oligotrophic conditions. Median concentrations of total nitrogen (unfiltered water) ranged from about 0.14 mg/L (Deep, Tapps Island, and Dike 2B sites) to about 0.18 mg/L (Allan Yorke and Lake Inlet sites). Chlorophyll a concentrations were low with median concentrations of 2.16 micrograms per liter (mg/L) or less. The majority of chlorophyll a concentrations were well below the Oregon Department of Environmental Quality action level of 10 mg/L. Using the Carlson Trophic-Status Index and average measures of transparency, chlorophyll a , and total phosphorus data from this study, Lake Tapps generally fits within the oligotrophic classification, but with a few exceptions. At Allan Yorke, Lake Inlet, and Southeast Arm sites, the chlorophyll a and total phosphorus indexes of nearly 40 approach the upper limit of oligotrophic conditions. In addition, average concentrations of total phosphorus at Lake Inlet and Southeast Arm are at Nürnberg's (1996) threshold concentration of 0.01 mg/L, which suggests a slight tendency towards mesotrophic conditions at these two sites during summer July–September. On the basis of epilimnetic nitrogen to phosphorus concentration ratios of greater than 17, Lake Tapps primary production is phosphorus limited at all but two study sites. At the Lake Inlet and Southeast Arm sites, ratios of 15 and 16, respectively, for the summer period suggest either nitrogen or phosphorus (or both) may limit algal growth. Water samples collected at the Allan Yorke, Snag Island, and Lake Outlet study sites were screened for the presence of more than 250 organic chemicals. A total of 14 compounds were detected in trace amounts (or determined to be present) at one or more of the 3 sites. The Allan Yorke site had 9 detections, the Snag Island site had 10 detections, and the Lake Outlet site had 5 detections of compounds mostly belonging to the group of wastewater indicator chemicals. Compounds detected (or with verified presence) at all three sites included the herbicide 2,4-D, the insecticide and mosquito repellant DEET, the herbicide fluridone used for Eurasian watermilfoil eradication, and the herbicide prometon. The largest concentrations of these compounds were in samples from the Allan Yorke site; the lowest concentrations were from the Lake Outlet site.

Washington↗
USGS2019

Sand Creek characterization study for Oncorhynchus clarkii virginalis (Rio Grande Cutthroat Trout), Great Sand Dunes National Park and Preserve, Colorado

The Oncorhynchus clarkii virginalis (Rio Grande cutthroat trout, RGCT) has undergone extensive declines in distribution and population. The RGCT is the southernmost distributed subspecies of cutthroat trout. Native to the Rio Grande Basin in Colorado and New Mexico, the subspecies is also found in the headwaters of the Pecos River and Canadian River basins in New Mexico. Currently, RGCT populations represent approximately 12 percent of the historic distribution. There are many factors that have contributed to the decline of the RGCT including small population sizes; hybridization with non-native salmonids; competition with non-native salmonids; angling; and loss of habitat resulting from wildfire, stream drying, disease, increased water temperatures; and poor land management. The eastern side of Colorado’s Rio Grande Basin is also home to Great Sand Dunes National Park and Preserve and the Sand Creek watershed. This study was designed to (1) characterize current physical and biological conditions of waterbodies within the Sand Creek watershed, from headwaters to lower terminus near the dune field; (2) characterize the spatial extent of existing fisheries within the Sand Creek watershed to inform the scope of potential future reclamation efforts; and (3) evaluate key limiting factors for a future native RGCT reintroduction. Bathymetric profiles were completed for two lakes within the upper Sand Creek drainage to characterize the physical geometry of each lake and to estimate the total lake volume required for future piscicide treatment and (or) fish removal efforts. Physical and biological conditions evaluated included stream water temperature and intermittency, discharge, and the genetics and existing fish community distribution and composition within the Sand Creek watershed were key components of this study. A baseline established the geographic extent and biological constraints factored into future piscicide treatment planning and native trout reintroduction efforts. As a result of this work, the Sand Creek watershed can be broken up into several distinct categories: Lakes that are good candidates for reclamation and reintroduction of RGCT, lakes that are poor candidates for reclamation, streams that currently have fish and are good candidates for reclamation and reintroduction, streams that currently lack fish and may be good candidates for introduction of RGCT, and streams that currently lack fish and are not good candidates for introduction of RGCT. This characterization study report is intended to inform State and Federal managers of the likelihood that the Sand Creek watershed can support a sustainable population of RGCT should they be reintroduced.

Colorado↗