Geology topics

Scott D. Evans

Publications and source records attributed to Scott D. Evans.

26 records · Page 2Linked to original sources

USGS2013

Behavior and dam passage of juvenile Chinook salmon at Cougar Reservoir and Dam, Oregon, March 2011 - February 2012

The movements and dam passage of juvenile Chinook salmon implanted with acoustic transmitters and passive integrated transponder tags were studied at Cougar Reservoir and Dam, near Springfield, Oregon. The purpose of the study was to provide information to aid with decisions about potential alternatives for improving downstream passage conditions for juvenile salmonids in this flood-control reservoir. In 2011, a total of 411 hatchery fish and 26 wild fish were tagged and released during a 3-month period in the spring, and another 356 hatchery fish and 117 wild fish were released during a 3-month period in the fall. A series of 16 autonomous hydrophones throughout the reservoir and 12 hydrophones in a collective system near the dam outlet were used to determine general movements and dam passage of the fish over the life of the acoustic transmitter, which was expected to be about 3 months. Movements within the reservoir were directional, and it was common for fish to migrate repeatedly from the head of the reservoir downstream to the dam outlet and back to the head of the reservoir. Most fish were detected near the temperature control tower at least once. The median time from release near the head of the reservoir to detection within about 100 meters of the dam outlet at the temperature control tower was between 5.7 and 10.8 days, depending on season and fish origin. Dam passage events occurred over a wider range of dates in the spring and summer than in the fall and winter, but dam passage numbers were greatest during the fall and winter. A total of 10.5 percent (43 of 411) of the hatchery fish and 15.4 percent (4 of 26) of the wild fish released in the spring are assumed to have passed the dam, whereas a total of 25.3 percent (90 of 356) of the hatchery fish and 16.9 percent (30 of 117) of the wild fish released in the fall are assumed to have passed the dam. A small number of fish passed the dam after their transmitters had stopped working and were detected at passive integrated transponder detectors at various locations downstream of the dam, indicating some tagged fish passed the dam undetected. The rate of dam passage was affected by diel period, discharge, and reservoir elevation. Diel period was the most influential factor of those examined, with nighttime dam passage rates about 9 times greater than daytime rates, depending on the distance of fish from the dam outlet. Dam passage rates also were positively related to dam discharge, and negatively related to reservoir elevation. In the operational condition used as an example, fish approached the dam outlet at the temperature control tower from the south and east and, when most fish got near the tower, they were directly in front of it. In many cases, the results for wild and hatchery fish were similar, or the results suggested hatchery fish could be reasonable surrogates for wild fish. Hatchery-origin and wild-origin fish behaved similarly in the following ways: their general movements in the reservoir; the timing of their dam passage; and the effects of diel period, discharge, and elevation on their passage rates. Parasitic copepods were present on most wild fish examined, and the mortality of wild fish during capture, handling and tagging was much greater than that of hatchery fish. This suggests that the ability of wild fish to cope with stressors may be less than that of fish directly from the hatchery.

Oregon↗

USGS2012

Interim results from a study of the behavior of juvenile Chinook salmon at Cougar Reservoir and Dam, Oregon, March--August 2011

The movements and dam passage of yearling juvenile Chinook salmon implanted with acoustic transmitters and passive integrated transponder tags were studied at Cougar Reservoir and Dam, near Springfield, Oregon. A total of 411 hatchery fish and 26 wild fish were tagged and released between March 7 and May 21, 2011. A series of 16 autonomous hydrophones placed throughout the reservoir were used to determine general fish movements over the life of the acoustic transmitter, which was expected to be 91 days. Movements within the reservoir were directional, and it was common for fish to migrate repeatedly from the head of the reservoir downstream to the dam outlet and back. The dam passage rate was 11.2 percent (95-percent confidence interval 7.8–14.6 percent) for hatchery fish and 15.4 percent (95-percent confidence interval -1.0–31.8 percent) for wild fish within 91 days from release. Most fish passage occurred at night. The median time from release to dam passage was 34.5 days for hatchery fish and 34.2 days for wild fish. A system of hydrophones near the dam outlet, a temperature control tower, was used to estimate positions of fish in three dimensions to enable detailed analyses of fish behavior near the tower. Analyses of these data indicate that hourly averaged depths of fish within a distance of 74 m from the upstream face of the tower ranged from 0.6 to 9.6 meters, with a median depth of 3.6 meters for hatchery fish and 3.4 meters for wild fish. Dam discharge rates and the diurnal period affected the rates of dam passage. Rates of dam passage were similar when the dam discharge rate was less than 1,200 cubic feet per second, but increased sharply at higher discharges. The rate of dam passage at night was 4.4–7.8 times greater than during the day, depending on the distance of fish from the dam. This report is an interim summary of data collected as of August 3, 2011, for planning purposes.

Oregon↗

USGS2012

A multi-year analysis of spillway survival for juvenile salmonids as a function of spill bay operations at McNary Dam, Washington and Oregon, 2004-09

We analyzed 6 years (2004-09) of passage and survival data collected at McNary Dam to examine how spill bay operations affect survival of juvenile salmonids passing through the spillway at McNary Dam. We also examined the relations between spill bay operations and survival through the juvenile fish bypass in an attempt to determine if survival through the bypass is influenced by spill bay operations. We used a Cormack-Jolly-Seber release-recapture model (CJS model) to determine how the survival of juvenile salmonids passing through McNary Dam relates to spill bay operations. Results of these analyses, while not designed to yield predictive models, can be used to help develop dam-operation strategies that optimize juvenile salmonid survival. For example, increasing total discharge typically had a positive effect on both spillway and bypass survival for all species except sockeye salmon ( Oncorhynchus nerka ). Likewise, an increase in spill bay discharge improved spillway survival for yearling Chinook salmon ( Oncorhynchus tshawytscha ), and an increase in spillway discharge positively affected spillway survival for juvenile steelhead ( Oncorhynchus mykiss ). The strong linear relation between increased spill and increased survival indicates that increasing the amount of water through the spillway is one strategy that could be used to improve spillway survival for yearling Chinook salmon and juvenile steelhead. However, increased spill did not improve spillway survival for subyearling Chinook salmon and sockeye salmon. Our results indicate that a uniform spill pattern would provide the highest spillway survival and bypass survival for subyearling Chinook salmon. Conversely, a predominantly south spill pattern provided the highest spillway survival for yearling Chinook salmon and juvenile steelhead. Although spill pattern was not a factor for spillway survival of sockeye salmon, spill bay operations that optimize passage through the north and south spill bays maximized spillway survival for this species. Bypass survival of yearling Chinook salmon could be improved by optimizing conditions to facilitate bypass passage at night, but the method to do so is not apparent from this analysis because photoperiod was the only factor affecting bypass survival based on the best and only supported model. Bypass survival of juvenile steelhead would benefit from lower water temperatures and increased total and spillway discharge. Likewise, subyearling Chinook salmon bypass survival would improve with lower water temperatures, increased total discharge, and a uniform spill pattern.

Oregon;Washington↗

USGS2012

Passage probabilities of juvenile Chinook salmon through the powerhouse and regulating outlet at Cougar Dam, Oregon, 2011

Cougar Dam near Springfield, Oregon, is one of several federally owned and operated flood-control projects within the Willamette Valley of western Oregon that were determined by the National Oceanic and Atmospheric Administration’s National Marine Fisheries Service in 2008 to impact the long-term viability of several salmonid stocks. In response to this ruling, the U.S. Army Corps of Engineers is looking for means to reduce impacts to salmonids, including improving downstream passage of juvenile salmonids at Cougar Dam. This study of juvenile Chinook salmon ( Oncorhynchus tshawytscha ) passage at Cougar Dam was conducted to inform decisions about potential improvements for downstream fish passage. The primary objective of the study was to estimate route-specific passage probabilities of yearling Chinook salmon at Cougar Dam. The study was conducted using fish from a nearby hatchery surgically implanted with radio transmitters and passive integrated transponder (PIT) tags and released near the entrance of a temperature control tower through which all water going through the dam must pass. Water passing through the temperature control tower may be routed through a penstock to a powerhouse with two Francis turbines, or to a spillway-like structure called the regulating outlet. Secondary objectives of the study were to estimate the probability that fish enter a bypass at a non-federal facility downstream, and to estimate dam-passage and in-river fish survival. Dam operating conditions during the study included an average forebay elevation of 1,580 feet (National Geodetic Vertical Datum of 1929) and an average of 48.2 percent of the total dam discharge of 1,106 cubic feet per second passing through a regulating outlet opening of 1.25 feet. Dam passage probability was greatest at night (0.8741 standard error [SE] 0.0265) and primarily through the regulating outlet (0.8896 SE 0.0617 day; 0.9417 SE 0.0175 night). The joint probability of entering the bypass at Leaburg Dam and being detected at the PIT system within the bypass was 0.0755 (SE 0.0363), but some fish were known to pass the PIT system undetected, indicating that the true probability of entering the bypass was underestimated. The estimated survival of fish passing through the temperature control tower, through the dam, and to a site at a bridge over the South Fork of the McKenzie River 3.9 kilometers downstream was 0.3680 (SE 0.1322) for fish passing through the powerhouse, and 0.4247 (SE 0.0440) for fish passing through the regulating outlet. The estimated in-river survival through the 37.3 kilometers from the bridge to a site at Leaburg Hatchery on the McKenzie River was 0.5857 (SE 0.2227) for fish that had passed through the powerhouse, and 0.4537 (SE 0.0551) for fish that had passed through the regulating outlet.

Oregon↗

USGS2012

Optimization of radio telemetry receiving systems

The performance of radio telemetry receiving systems can be affected by numerous factors, thus it is important for researchers to understand these factors when designing a radio telemetry study. One approach that has been used to describe these factors is the radio system equation which defines six variables that affect radio receiving systems (Sisak and Lotimer 1998; Section 5.1). This equation is: P r = P t – L w – L awi –L air + G r – L rtl where P r is the received power level, P t is the transmitted power level, L w is the signal loss in water, L awi is the loss at the air-water interface, L air is the loss in air, G r is the gain of the receive antenna, and L rtl is the loss of the receive transmission line (Figure 1). Three of these variables (L w , L air , and L awi ) are affected by factors that researchers have little control over (i.e., distance traveled by a given radio signal, water conductivity and temperature, angle of refraction of the signal as it exits the water). However, P t , G r , and L rtl can be influenced by the user and planning for the effects of each is an essential first step towards designing a radio receiving system that operates at the highest level possible. The first of these factors P t , is addressed while choosing which transmitter to purchase, a topic which was covered in a previous Section. Much of the information that we present will focus on maximizing the strength of the signal that is received by the radio receiver which is affected by G r and L rtl . Additionally, we will cover techniques to minimize the effects of ambient (or background) noise which is also an important aspect of radio receiving systems. Ambient noise is important because low signal-to-noise ratios will result in signals that cannot be detected by the receiving system. In other words, tagged fish within range of the receiving system are not detected because ambient noise levels exceed the received signal at the receiver.

Book chapter↗

USGS2011

Summary of juvenile salmonid passage and survival at McNary Dam-Acoustic survival studies, 2006-09

Passage and survival data were collected at McNary Dam between 2006 and 2009. These data have provided critical information for resource managers to implement structural and operational changes designed to improve the survival of juvenile salmonids as they migrate past the dam. Given the importance of these annual studies, the primary objectives of this report were to summarize the findings of these annual studies to ensure that passage and survival metrics are consistently calculated and reported across all years and to consolidate this information in a single document, thereby making it easier to reference. It is worth noting that this report does not contain all the information from all the annual reports. The intent of this report was to summarize the key findings from multiple years of research. The reader is encouraged to reference the annual reports if more detailed information is needed. Chapter 1 summarizes existing behavior, passage, and survival results for fish released 10 rkm upstream of McNary Dam and from the McNary Dam tailrace during 2006-09. Chapter 2 summarizes existing behavior, passage, and survival results for fish released in the mid-Columbia River and detected at McNary Dam during 2006-09. Results from 2006 indicated that higher spill discharge generally resulted in higher fish passage through spill, and in turn, higher fish survival through the entire dam. Within the spillway, passage effectiveness was highest for the south spill bays, adjacent to the powerhouse. Increased passage in this area, combined with detailed 3-dimensional approach paths, aided in the design and location of the temporary spillway weirs (TSWs) at McNary Dam prior to the 2007 migration of juvenile salmonids. During the 2007 study, the TSWs were tested under two spill treatments during the spring and summer: a "2006 Modified spill," and a "2007 test spill." In the spring, slightly higher discharge through spill bays 14-17 was the primary difference between the spill treatments tested. During the summer, spill treatments were characterized by a high (60 percent) and low (40 percent) percent flow of the total discharge going through the spillway. Flow through the TSWs represented about 7-8 percent of total project discharge in spring and about 10-11 percent of total project discharge in summer. Overall, the TSWs passed 24 percent of yearling Chinook salmon and 27 percent of subyearling Chinook salmon, but passed about 65 percent of juvenile steelhead. In spring, there was little evidence for an effect of spill treatment on either fish passage or survival, however, this was not surprising given there was a relatively small difference between spill treatments. For subyearling Chinook salmon during the summer study, high spill discharge resulted in higher fish passage through the spillway and lower fish passage through the powerhouse. Season wide survival (paired-release) for yearling and subyearling Chinook salmon was 0.98 and 0.92 (SE<0.04) through TSW 20, and 0.96 and 0.97 (SE<0.04) through TSW 22, respectively. Season-wide survival (single-release) for juvenile steelhead was 0.98 (SE=0.024) through TSW 20, and 0.90 (SE=0.02) through TSW 22. The extent to which location and structural design contributed to the differences observed between the two TSWs was uncertain. Nonetheless, the TSWs performed similarly to surface-oriented fish passage structures at other locations and appear to be a useful fish passage alternative at McNary Dam. The 2008 and 2009 studies confirmed previous results showing high survival for fish passing through the TSWs, especially juvenile steelhead. Although the number of all fish species passing through the TSWs was lower in 2008 and 2009 compared to 2007, fish passage efficiency for juvenile steelhead and subyearling Chinook salmon was higher in years with the TSWs, compared to 2006, before the TSWs were in place.

Washington;Oregon↗

USGS2010

Assessing survival of Mid-Columbia River released juvenile salmonids at McNary Dam, Washington, 2008-09

Few studies have evaluated survival of juvenile salmon over long river reaches in the Columbia River and information regarding the survival of sockeye salmon at lower Columbia River dams is lacking. To address these information gaps, the U.S. Geological Survey was contracted by the U.S. Army Corps of Engineers to evaluate the possibility of using tagged fish released in the Mid-Columbia River to assess passage and survival at and downstream of McNary Dam. Using the acoustic telemetry systems already in place for a passage and survival study at McNary Dam, fish released from the tailraces of Wells, Rocky Reach, Rock Island, Wanapum, and Priest Rapids Dams were detected at McNary Dam and at the subsequent downstream arrays. These data were used to generate route-specific survival probabilities using single-release models from fish released in the Mid-Columbia River. We document trends in passage and survival probabilities at McNary Dam for yearling Chinook and sockeye salmon and juvenile steelhead released during studies in the Mid-Columbia River. Trends in the survival and passage of these juvenile salmonid species are presented and discussed. However, comparisons made across years and between study groups are not possible because of differences in the source of the test fish, the type of acoustic tags used, the absence of the use of passive integrated transponder tags in some of the release groups, differences in tagging and release protocols, annual differences in dam operations and configurations, differences in how the survival models were constructed (that is, number of routes that could be estimated given the number of fish detected), and the number and length of reaches included in the analysis (downstream reach length and arrays). Despite these differences, the data we present offer a unique opportunity to examine the migration behavior and survival of a group of fish that otherwise would not be studied. This is particularly true for sockeye salmon because little information is available about their survival as they pass hydroelectric dams in the lower Columbia River. Collecting information on fish released in the Mid-Columbia River, as well as on fish released 8 kilometers upstream of McNary Dam, allowed us to evaluate similarities and differences in passage and survival probabilities. In general, juvenile salmonids released in the Mid-Columbia River and detected at and downstream of McNary Dam showed trends in passage and survival probabilities that were similar to fish released 8 kilometers upstream of McNary Dam. This suggests that increased migration time or length of migration had little effect on behavior and survival of Mid-Columbia River released juvenile salmonids detected at McNary Dam.

Open-File Report↗

USGS2009

Evaluation of strobe lights to reduce turbine entrainment of juvenile steelhead ( Oncorhynchus mykiss ) at Cowlitz Falls Dam, Washington

We conducted a radiotelemetry evaluation to determine if strobe lights could be used to decrease turbine entrainment of juvenile steelhead ( Oncorhynchus mykiss ) at Cowlitz Falls Dam, Washington. We found that radio-tagged juvenile steelhead approached and entered two spillbays (one lighted, one unlighted) in equal proportions. However, the presence of strobe lights was associated with decreased spillbay residence time of juvenile steelhead and increased passage through induction slots (secondary turbine intakes located upstream of the ogee on the spillway). Mean residence time of tagged fish inside the lighted spillbay was 14 min compared to 62 min inside the unlighted spillbay. Radio-tagged steelhead passed through induction slots at a higher proportion in the lighted spillbay (55%) than in the unlighted spillbay (26%). Recent studies have suggested that strobe lights can induce torpor in juvenile salmonids. We believe that strobe light exposure affected fish in our study at a location where they were susceptible to high flows thereby reducing mean residence time and increasing the proportion of tagged fish entering induction slots in the lighted spillbay. Our results suggest that factors such as deployment location, exposure, and flow are important variables that should be considered when evaluating strobe lights as a potential fish-deterring management tool.

Northwest Science↗