Benthic Macroinvertebrates of Hells Canyon
Ralph Myers Water Quality Program Supervisor
Aaron Foster Environmental Technician
Technical Report Appendix E.3.1-8 July 2003 Hells Canyon Complex FERC No. 1971 Copyright © 2003 by Idaho Power Company
Idaho Power Company Benthic Macroinvertebrates of Hells Canyon
TABLE OF CONTENTS
Table of Contents...... i
List of Tables ...... iii
List of Figures...... iii
List of Appendices ...... iv
Abstract...... 1
1. Introduction...... 2
2. Study Area ...... 5
2.1.1. Upstream Reach...... 5
2.1.2. Reservoir Reach...... 7
2.1.3. Downstream Reach ...... 8
3. Plant Operations...... 9
3.1. Operational Overview...... 9
3.2. Seasonal Operations of Brownlee Reservoir ...... 10
4. Methods...... 11
4.1. Sampling Design...... 11
4.1.1. Upstream Reach...... 11
4.1.2. Reservoir Reach...... 11
4.1.3. Downstream Reach ...... 12
4.2. Field Methods ...... 13
4.2.1. Upstream Reach...... 13
4.2.2. Reservoir Reach...... 13
4.2.3. Downstream Reach ...... 14
4.3. Data Analysis...... 15
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4.3.1. Relative-abundance Index...... 15
4.3.2. Sample Composition...... 16
5. Results...... 16
5.1. Upstream Reach...... 16
5.2. Reservoir Reach...... 17
5.3. Downstream Reach ...... 17
6. Discussion...... 18
6.1. Upstream Reach...... 18
6.2. Downstream Reach ...... 19
7. Acknowledgments...... 20
8. Literature Cited ...... 21
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LIST OF TABLES
Table 1. Benthic macroinvertebrate sample distribution in the two reaches below, and above, the Hells Canyon dams complex, lower Snake River, 1998...... 25
Table 2. Benthic macroinvertebrate sample distribution in the reservoir reach of the Hells Canyon dams complex, lower Snake River, 1998...... 26
Table 3. Benthic macroinvertebrate taxa found in the upstream, reservoir, and downstream reaches of the lower Snake River, 1998...... 27
Table 4. Percent Gastropoda and relative abundance indices of selected molluscan taxa in the upstream reach (RM 340−395) above Brownlee Reservoir, 1998...... 28
Table 5. Benthic macroinvertebrate taxa found in the Brownlee Reservoir reach of the lower Snake River, 1998...... 29
Table 6. Benthic macroinvertebrate taxa found in the Oxbow Reservoir reach of the lower Snake River, 1998...... 30
Table 7. Benthic macroinvertebrate taxa found in the Hells Canyon Reservoir reach of the lower Snake River, 1998...... 31
Table 8. Relative abundance indices of selected molluscan taxa in the downstream reach (RM 219−246), 1998...... 32
Table 9. Percent Gastropoda of selected molluscan taxa in the downstream reach (RM 219−246) below Hells Canyon Reservoir, lower Snake River, 1998...... 33
LIST OF FIGURES
Figure 1. Study area for the upstream reach, RM 340 to RM 395...... 35
Figure 2. Study area and transect locations for sampling in the reservoir reach...... 37
Figure 3. Study area for the downstream reach...... 39
Figure 4. Example schematic showing sample design and subsampling process for a 5-river mile subreach in the upstream reach...... 41
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Figure 5. Example schematic showing sample design and subsampling process for a transect sampling in the reservoir reach...... 42
Figure 6. Example schematic showing sample design and subsamplng process sampling in the downstream reach...... 43
Figure 7. Taxonomic composition of analysis groups for samples collected in the upstream reach...... 44
Figure 8. Relative abundance index for samples collected in the upstream reach...... 45
Figure 9. Taxonomic composition for samples collected during October in the downstream reach...... 46
Figure 10. Relative abundance index for samples collected during October in the downstream reach...... 47
Figure 11. Taxonomic composition for samples collected during September in the downstream reach...... 48
Figure 12. Relative abundance index for samples collected during September in the downstream reach...... 49
LIST OF APPENDICES
Appendix 1. Taxa breakdown of taxa indentified from the upstream reach (RM 340−RM 395)...... 51
Appendix 2. Taxa list and phylogeny for taxa identified in the reservoir reach during all seasons...... 55
Appendix 3. Taxa list and phylogeny for taxa detected in the downstream reach (RM 219−RM 247)...... 59
Appendix 4. Taxa list and phylogeny for taxa detected in the downstream reach during winter and spring sampling (RM 189−RM 219)...... 65
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ABSTRACT
In 1998, IPC conducted a macroinvertebrate survey of the Snake River from Swan Falls Dam, (RM 458) downstream to the confluence of the Salmon River (RM 188). This 270-mile section of river was divided into three reaches for purposes of the study. This report presents results from samples collected from RM 395 to RM 188. Analyses to address several of the original objectives of the study were precluded by study design and sampling protocols. The Upstream Reach is defined as the portion of the Snake River from RM 395 to RM 340. Within this 55-mile reach of our study area, 2 composite dredge samples were collected at randomized sites within each five mile subreach. Trycorythodes sp. was the most common taxon while Hydropsyche sp. was also common in samples from this reach. Relative abundance of macroinvertebrates peaked in samples collected in the vicinity of the Payette River. Idaho springsnail (Pyrgulopsis idahoensis) occurred in the upstream reach. The second reach (Reservoir Reach) encompassed Brownlee, Oxbow, and Hells Canyon reservoirs. Here, collection methods varied from suction dredging, petite Ponar, to hand excavation, because of environmental constraints such as water level and temperatures. This variability of collection methods limited our analysis and interpretation of samples within the reservoir reach. The reservoir samples contained the highest number of taxa during spring sampling. Oxbow and Hells Canyon reservoir samples contained more taxa than samples from Brownlee Reservoir. Finally, the Downstream Reach included the Snake River from Hells Canyon Dam downstream to the confluence of the Snake and Salmon rivers. Our analysis of taxa composition in the Downstream Reach, was limited to that portion of the Snake River between Kirby Creek, (RM 219) and Hells Canyon Dam (RM 247). Platyhelminthes, oligochaetes, and gastropods were most common throughout the downstream reach. Four snail specimens identified in the field as Bliss Rapids snails (Taylorconcha serpenticola) were collected near Pine Bar. Taxonomic verification of those individuals remains uncertain. The exotic New Zealand mudsnail (Potamopyrgus antipodarum) occurred in all reaches of the study area, except for Brownlee or Hells Canyon reservoirs.
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1. INTRODUCTION
With few exceptions, dams and reservoirs regulate the rivers of the western United States. The Snake River of Idaho, Oregon, and Washington sustains many dams for the purpose of irrigation, flood control, commercial navigation, and hydropower generation. One complex of dams on the Snake River is the Hells Canyon Complex (HCC), which consists of three dams and associated power plants. These three dams—Brownlee, Oxbow, and Hells Canyon—are owned and operated by Idaho Power Company (IPC). The HCC produces nearly 1.2 megawatts (MW) of electricity, and is responsible for generating over two-thirds of IPC’s power. The HCC is a nonfederal waterpower project, licensed and regulated by the Federal Energy Regulatory Commission (FERC) as FERC No. 1971. FERC issued limited-term licenses for operations of the Hells Canyon, Oxbow, and Brownlee plants in 1955, and construction was completed in 1959, 1961, and 1968 for Brownlee, Oxbow, and Hells Canyon dams, respectively. The project license for the HCC will expire in July 2005.
The Snake River is a large lotic ecosystem (that is, an open ecosystem with flowing water). Benthic macroinvertebrates, those organisms that inhabit the bottom substrates of freshwater habitats for at least part of their lives, are an important component of the biota of the ecosystem. The prefix macro- further defines the invertebrates as those retained by sampling net mesh sizes 200 to 500 microns (µm) (Rosenberg and Resh 1992). Benthic macroinvertebrates are an integral part of this large river ecosystem and can be indicators (as shown by their distribution, diversity, and described ecosystem roles) of the integrity and properties of the river ecosystem.
Benthic macroinvertebrates play important roles in the trophic structure (or relationship of different organisms in the food chain) and energy processing of an aquatic ecosystem. They consume primary producers (those organisms that directly convert the sun’s energy into food) such as periphyton and macrophytes. This heterotrophic energy pathway provides a link between primary producers and tertiary consumers. Many benthic invertebrates function as secondary producers, serving as prey for fish, birds, and some small mammals. They also consume detritus (nonliving particulate organic matter), converting course particulate organic matter (CPOM) to fine particulate organic matter (FPOM).
The distribution and community structures of benthic macroinvertebrates are influenced by water discharge, temperature, and stream substrate characteristics (Reece and Richardson 2000). Ongoing environmental processes affecting the ecosystem—such as flow regulation and impoundment—also directly and indirectly influence these organisms. The response of a species or community to any or all of the influences helps investigators diagnose system conditions. In general, the benthic macroinvertebrate community is a product of evolution, natural environmental pressures, and responses to changes in their environment.
As a factor in the Snake River ecosystem, the HCC controls physical and chemical aspects of the river and therefore affects the benthic community. Many studies of the effects of dams on benthic communities have been completed and documented, including a review on the effects of flow patterns below large dams (Ward 1976). In May 1984 through 1988, Morgan et al. (1991) assessed benthic response to a revised flow-release schedule below the Brighton Hydroelectric
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Dam in Maryland. They found that the benthic community responded positively to a 25 to 35% reduction in extreme low and high flows. Blinn et al. (1995) looked at the influence of fluctuations in river discharge on the structure and function of the benthic community in the tailwaters of Glen Canyon Dam, Arizona. They found macroinvertebrate mass to be four times higher in the main, permanently submerged channel than in the varial, or fluctuation, zone. McKinney et al. (1999) examined how extended dry exposure (3 days) in the varial zone affected the benthic and rainbow trout communities of the Colorado River below Glen Canyon Dam. They concluded that exposure with sudden flow reduction could reduce standing crops of periphyton, macrophytes, and macroinvertebrate taxa, but the reductions had insignificant short- term consequences for rainbow trout.
Shannon et al. (2001) examined the impact of flood releases on the “aquatic food base” below Glen Canyon Dam. Scour and entrainment of benthic organisms was observed at all their study sites. Growns and Growns (2001) compared regulated sites below dams in the Hawkesbury- Nepean River system of Australia to unregulated sites on nearby streams. They concluded that the biological communities at the sites differed mainly because of the change (or difference) in hydrologic regime. Vinson (2001) examined 50 years of data on macroinvertebrate assemblages in two tailwater reaches below Flaming Gorge Dam, Utah. He looked at conditions before the dam and the long-term dynamics of the benthic assemblage downstream of the dam and then assessed the effects of a partial thermal restoration. Although his report covered a wide range of topics in the conclusions, of greater interest to this work was information about species loss and subsequent restoration efforts. He found that native species were lost through species introductions and community shifts; however, efforts to restore the original communities probably are not effective because the new community (the one that has evolved because of the addition of the dam and persists in the dam-dominated ecosystem) is established and tolerant of the operations and turbulence.
Brusven et al. (1974) conducted a synoptic study of aquatic insects below Hells Canyon Dam in 1973. At different water flow stages, they investigated standing crop, drift rates of principal insect species, and insect stranding. They also studied catchability and feeding habits of fish for 24 hours during sequential reductions in flow. They speculated from this 8-day study that water fluctuation causes ecological instability to the biota exposed during dewatering as well as deeper zones through disruption of normal photosynthesis and the decomposition processes. They found that the drift results indicated an obvious diel cycle. In addition, they concluded that drift propensity of aquatic insects generally increased during reduction of flows. Furthermore, they found insects, sculpin, algae, crayfish, and small clams among the stomach contents of fish captured during the study, providing support for the speculation that insect drift may be an important component of the fish food base below Hells Canyon Dam.
Our study was initially scoped and developed within the context of the HCC Collaborative Team Aquatic Resource Workgroup. The study was initiated in response to the need to describe characteristics of current relationships between benthic macroinvertebrates and physical, chemical, and biological components of the ecosystem. The original stated goal of the study was to describe the structure of the benthic community and its relationship to the environment, of which the HCC hydroelectric projects are a major component. Specific objectives were to:
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• Describe the existing benthic macroinvertebrate community of the reach above the HCC in terms of structure and function and determine its contribution to the complex through bioassessment;
• Describe benthic macroinvertebrate communities in the reservoirs and downstream of (or below) the Hells Canyon Dam and compare them with the community upstream of (or above) the complex for structure and function;
• Compare and contrast the benthic communities in the fluctuation zone and the main channel below the Hells Canyon Dam;
• Determine the magnitude of load-following impacts to the benthic community in terms of linear change in densities and distribution below Hells Canyon Dam; and,
• Assess the macroinvertebrates as a food base for other biological groups throughout the study reach.
A draft completion report was produced in 2001 and included in the draft HCC license application published and distributed for agency and public comment on July 2002. In November 2002, IPC became aware of potential inconsistencies in its macroinvertebrate database. An independent review identified issues that had potential implications regarding the data and draft completion report that were included in the draft HCC license application. Because of the potential errors IPC conducted a review and evaluation of Technical Report E.3.1-8 that had been distributed in its draft HCC license application. Because of time constraints, only the 1998 data and the additional data collected in 2002 regarding the potential occurrence of Taylorconcha serpenticola (Bliss Rapids snail) could be adequately evaluated for inclusion in the final report. As a result, the objectives addressed in this final report have been modified to include only objectives that could be defensibly supported by the 1998 and 2002 data collection. The modified objectives addressed by this report are to:
• Describe the existing benthic macroinvertebrate taxa in samples collected in the Snake River starting at the headwaters of Brownlee Reservoir and extending 55 miles upstream;
• Describe macroinvertebrate taxa in samples collected in Brownlee, Oxbow, and Hells Canyon reservoirs;
• Describe the existing macroinvertebrate composition in samples collected in the Snake River from Hells Canyon Dam downstream to the confluence of the Snake and Salmon rivers; and,
• Report any findings of Endangered Species Act (ESA) listed snail species within the study area.
Of special interest was the presence of endangered Bliss Rapids snails (Taylorconcha serpenticola), and threatened Idaho Springsnails (Pyrgulopsis idahoensis) reported in the draft completion report. Determining the presence of ESA listed species is important in defining the regulatory framework and scope of issues related to licensing the HCC. In addition, the status of the New Zealand mudsnail (Potamopyrgus antipodarum) was of particular interest because it has
Page 4 Hells Canyon Complex Idaho Power Company Benthic Macroinvertebrates of Hells Canyon been identified as significant to the persistence of listed snails, and other native aquatic biota of the Snake River (USFWS 1995).
2. STUDY AREA
To specifically describe the benthic macroinvertebrates associated with the HCC, IPC sampled aquatic macroinvertebrates in the mainstem Snake River within the upstream, reservoir, and downstream reaches of the HCC study area during 1998. Each reach has unique features that are important to describe and understand the biological communities, including macroinvertebrates, of the Snake River.
2.1.1. Upstream Reach
The upstream reach in this study is the unimpounded portion of the Snake River that extends from the headwaters of Brownlee Reservoir (RM 340) 55 miles upstream to RM 395 (Figure 1). In the upstream reach, the Snake River can be characterized as a low-gradient (0.2 to 0.4 m/km) river, with several island complexes. Most of this reach is surrounded by farmland and rural development on flat to gentle topography. Stream substrates are dominated by small particles, with fines and sand to medium-sized cobbles prevalent throughout. The Snake River in this area reflects heavy use since large amounts of water are diverted annually for agricultural and urban uses upstream and throughout this reach. The geology within the upstream reach is distinctive and lends itself well to the intensive agricultural and urban uses prevalent in the valley. Where most of the Snake River Plain was formed by lava flow, this reach of the study area consists mostly of deposited sediments (Malde 1965). Beginning approximately 20 miles downstream of Twin Falls, Idaho, the dominating basalt plateaus of the Snake River canyon are covered by a thickening mass of detrital deposits (Malde 1965). Finally, at a point very near the Oregon border, the basalt plateaus disappear entirely, and the Snake River flows through the wide, heavily sedimented valley that characterizes this upstream reach. This valley and upstream reach end downstream of Weiser where the Snake River enters the mountains of Hells Canyon.
Five major tributaries enter this 55 mile reach of the Snake River. The Weiser, Payette, Malheur, Boise, and Owyhee rivers all enter the Snake River within this reach (Figure 1). These tributaries and their watersheds are described in more detail below because of their importance to the physical, chemical, and biological features of the Snake River.
Weiser River—The 100-mile long Weiser River flows southward through predominately scrub- covered rolling hills to its confluence with the Snake River at Weiser, Idaho. The Weiser River basin drains a total of 1,076,165 acres of land, almost entirely underlain by basalt flows (Ross and Savage 1967). Basalt mantled by alluvium covers the valleys, allowing both the intensive irrigated and dry farming common to the area. This mantling predisposes these lowlands to flooding, especially in late winter and early spring when flows are highest. The Weiser River watershed ranges in elevation from 7,970 to 2,097 feet, with a mean elevation of 4,032 feet. Predominant vegetation within the Weiser River drainage is shrubland, and the primary land use is agriculture.
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Payette River—The Payette River, which drains over 2 million acres of west-central Idaho (Figure 2), is the tributary that contributes the most water to the Snake River between the Henrys Fork and the Salmon River. The basin’s forested uplands lie primarily on granitic rock, although the majority of the lower basin is underlain by basalt (Ross and Savage 1967). Lowlands are mantled by alluvium. Flows resulting from snowmelt are usually highest in June, though high flows can also be common after heavy rains in late winter and early spring. As with the Weiser River basin, the dominant vegetation within this watershed is shrubland, and the prevailing land use is agriculture.
Lower Malheur River—The Malheur River drains approximately 2 million acres. However, the lower Malheur River drainage comprises 580,545 acres of predominately high desert shrubland. The Malheur River flows primarily through rock terrain that is principally composed of volcanic, rock. The lower portion of the watershed has significant deposits of ash washed down from higher elevations (Orr 1992). The area classified as the lower Malheur River watershed ranges from an elevation of 5,887 to 2,111 feet, with a mean elevation of 3,540 feet. Because of the low elevation and lack of thermal cover within the basin, peak runoff is early, usually during April. Rangeland is the predominant land use. In lower portions of the watershed, the Malheur River traverses the Snake River Plain where irrigated farming is the dominant land use and produces large volumes of irrigation return flows to the river.
Lower Boise River—The 190-mile Boise River flows westward from the Sawtooth Mountains and drains over 2.5 million acres. Its confluence with the Snake River lies approximately 20 miles northwest of Caldwell, Idaho. The highest elevations are forested and underlain almost entirely by granitic rock (Mullins 1998). However, the geology of the lower Boise River is a matrix of alluvium and volcanic rock. The floodplain is composed of unconsolidated alluvium (silt, sand, and coarse well-sorted gravel), buried beneath a blanket of soil, often as much as 20 feet thick. Terraces flanking the river on the north and south are composed of unconsolidated clay, silt, sand, and well-sorted gravel (Mullins 1998). The lower Boise River flows through Ada and Canyon counties, the most industrialized and urbanized area in Idaho. Streamflows in the river are primarily influenced by reservoir regulation, irrigation withdrawals, irrigation returns, and shallow groundwater seepage (Thomas and Dion 1974). The tremendous development and “urban sprawl” that the lower Boise River basin has seen in the past 30 years has significantly increased the amount of stormwater runoff into the Boise River (Kjelstrom 1995). This lower portion of the watershed encompasses a total area of 866,766.4 acres. Here the watershed ranges in elevation from 6,880 to 2,195 feet, with a mean elevation of 2,937 feet.
Lower Owyhee River—The Owyhee River drains almost 5.5 million acres. The lower Owyhee River watershed, is classified as predominately shrubland, and consists of 1,326,824 acres. This lower section of the drainage ranges in elevation from 6,453 to 2,198 feet, with a mean elevation of 4,067 feet. Within this lower section of the Owyhee River watershed, agriculture and grazing are the predominant land uses, resulting in a significant amount of agricultural irrigation return. The characteristics of the lower watershed mirror those of the Malheur River in many ways. For example, flows peak in late April to early May, and the predominant geology is a conglomeration of deposited ash and lavas from the middle Miocene epoch (Orr 1992).
Each of the above-described tributaries lose much of their summer water flow volume to lowland
Page 6 Hells Canyon Complex Idaho Power Company Benthic Macroinvertebrates of Hells Canyon irrigation diversion. Irrigation return flows to tributary lower reaches and directly to the Snake River are a common feature of these streams and contribute heavy loadings of nutrients, sediments, organic matter, and bacteria to the rivers.
2.1.2. Reservoir Reach
Brownlee Reservoir—Brownlee Reservoir, completed in 1959, is the uppermost reservoir of the HCC (Figure 2). A large storage reservoir with approximately 1 million acre feet of active storage, the entire reservoir volume is approximately 1.4 million acre feet. At full pool (633 m [2,077 ft] above mean sea level [msl]), Brownlee Reservoir has a surface area of 6,100 hectares (ha) (15,000 acres) and is 93 km (58 miles) long. Mean depth is approximately 30.5 m (100 ft), with a maximum depth of 91.4 m (300 ft) near the dam. The average hydraulic retention time is 34 days (Myers et al. 2001).
Shorelines are typically steep and consist of bedrock or mixtures of boulders, sand, and gravel substrate. Large rock outcrops occur throughout the entire length. Shoreline substrates are quite variable with some areas dominated by sand and other areas characterized by bedrock and small to medium-sized cobbles and boulders of angular basalt. Shoreline slopes in the range of 20 to 30% are most common. One of the most dominant habitat features of Brownlee Reservoir is the transition zone (RM 308−325). The transition zone, typical of storage reservoirs on large rivers, is the part of the reservoir where habitat is transitioning from riverine to lacustrine. Typical characteristics of the transition zone include deposition of fine sediment, high densities of phytoplankton, and low summer dissolved oxygen levels. Brownlee Reservoir serves as a sedimentation basin for the Snake River, resulting in water of measurably lower turbidity and phosphorus content leaving the reservoir than entering (Myers et al. 2001).
Brownlee Reservoir substantially affects the downstream system, in part because of deep-water releases. The reservoir is thermally stratified throughout the summer, with a relatively strong thermocline located at a depth of approximately 40 m (Myers et al. 2001). Water temperatures in the upper 10 m of Brownlee Reservoir remain above 21 °C from July to September, with peaks approaching 26 to 29 °C in late summer (Ebel and Koski 1968, Goodnight 1971, Rohrer 1984). Typically, summer outflow water temperatures are cooler than inflowing river temperatures (Myers et al. 2001). During the fall, outflowing water temperatures are warmer than inflowing water temperatures (Ebel and Koski 1968). Milligan et al. (1983) classified Brownlee, Oxbow, and Hells Canyon reservoirs as meso-eutrophic reservoirs . Brownlee and Hells Canyon reservoirs thermally stratify during the summer months, resulting in hypolimnetic anoxia (Ebel and Koski 1968; Myers et al. 2001).
Oxbow Reservoir—Oxbow Reservoir is a small re-regulating reservoir approximately 19 km (11.8 miles) long with a total volume of 57,500 acre feet. The reservoir is surrounded by moderate to steep topography (20 to 75% slopes). The Snake River from the tailrace of Brownlee Dam to the mouth of Wildhorse Creek (1 mile downstream) is a swift, narrow channel. Oxbow Reservoir is relatively narrow with a mean width of 242 m (795 ft) and shallow, with a mean depth of 15 m (50 ft). It’s maximum depth is approximately 25 m (81 feet). The average hydraulic retention time for Oxbow Reservoir is 1.4 days (Myers et al. 2001). Shorelines are primarily basalt outcrops and talus, except where small tributaries have created alluvial fans. Daily fluctuations upward of 1.2 m (4 ft) are common.
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Hells Canyon Reservoir—Hells Canyon Reservoir, constructed in 1967, is a re-regulating reservoir approximately 35 km (21.7 miles) long with a total volume of 170,000 acre feet. Its maximum depth is approximately 75 m (245 ft), and has a mean width of 305 m (1,000 ft). The average hydraulic retention time for Hells Canyon Reservoir is 4 days (Myers et al. 2001). Reservoir shorelines are generally very steep, and substrates consist primarily of basalt outcrops and talus slopes. The unique design of the powerhouse and dam of the Oxbow Project leaves a 3.7-km (2.3-mile) stretch of the original river channel from Oxbow Dam downstream to the outflow of the powerhouse with a minimum flow of 100 cubic feet per second (cfs). The backwater effect of Hells Canyon Reservoir can extend over almost the entire length of the 2.3-mile bypassed reach, creating a relatively shallow backwater area with low velocities between Oxbow Dam and the Oxbow Powerhouse. Indian Creek enters the Snake River in the bypassed reach. Shorelines downstream in the Hells Canyon Reservoir are generally very steep, and substrates consist primarily of basalt outcrops and talus slopes.
2.1.3. Downstream Reach
The Snake River in the downstream reach is a high-gradient river (1.8 m/km) with large rapids, and diverse hydraulic features ranging from shallow riffles to deep pools (Figure 3). Substrates range from large basalt outcrops and boulders to cobble and sandbars. This unimpounded reach of the Snake River flows through a deep gorge, and is surrounded at the upstream end by nearly vertical cliff faces. The canyon becomes somewhat wider downstream near Johnson Bar (RM 230), with steep topography continuing downstream to the confluence of the Snake and Salmon rivers.
Throughout the canyon, topography is generally steep and broken, with slopes dominated by rock outcrops and talus slopes. At the deepest points of the canyon, the walls rise almost vertically. Canyon walls are deeply dissected by numerous side canyons that contain tributaries to the Snake River. The Seven Devils Mountains to the east and Wallowa Mountains to the west form the upper reaches of the canyon walls. These mountains form a series of jagged peaks reaching almost 10,000 feet, with subalpine and alpine conditions (USFS 1990) above 6,000 ft msl on both sides of the canyon.
Hells Canyon was formed as the Snake River eroded through the Blue Mountains in Oregon and Seven Devil Mountains in Idaho (U.S. Department of Energy 1985). The Snake River has existed since the Pliocene epoch and probably cut to its present level during the Pleistocene. During the Pleistocene, glacial meltwater provided abundant runoff for downcutting, while regional uplifting created weak points in the 2,000- to 3,000-foot-thick basalt plateau that overlaid the Blue and Seven Devils mountains. Resulting erosion formed the currently observed drainage pattern that established the Snake River (U.S. Department of Energy 1985). Northeast- trending, high-angle fault patterns characterize the extensive Snake River fault system running throughout the study area (Fitzgerald 1982). Besides basalt, other rock types are also present within the study area. Extensive limestone outcrops are found in some tributary drainage areas, and local granitic outcrops also occur.
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3. PLANT OPERATIONS
3.1. Operational Overview
Operations of the three projects of the HCC are closely coordinated to generate electricity and to serve many other public purposes. Currently, over 400,000 customers rely on IPC’s hydro and thermal generation system for power. The HCC is an integral part of IPC’s generation system. Winter and summer operations are particularly important because energy needs are highest during those seasons. In wintertime, customers need extra electricity for lighting and heating. During the summer, electricity demand is high for air conditioning and irrigation pumping.
IPC operates the HCC to comply with the FERC license, as well as to accommodate other concerns, such as recreational use, environmental conditions and voluntary arrangements. One of these arrangements includes the Fall Chinook Recovery Plan adopted in 1991. A second was the cooperative arrangement that IPC had with federal interests in implementing portions of the Federal Columbia River Power System (FCRPS) biological opinion flow augmentation between 1995 and 2001. The FCRPS biological opinion flow augmentation is intended to avoid jeopardy from the FCRPS operations below the HCC.
Brownlee Reservoir is the only one of the three HCC facilities—and IPC’s only project—with significant storage. It has 101 vertical feet of active storage capacity, totaling approximately 1 million acre-feet of water. On the other hand, Oxbow and Hells Canyon reservoirs have significantly smaller active storage capacities—approximately 0.5 and 1.0% of Brownlee Reservoir’s volume, respectively.
Brownlee Dam’s hydraulic capacity is also the largest of the three projects. Its powerhouse capacity is approximately 35,000 cubic feet per second (cfs), while the Oxbow and Hells Canyon powerhouses have hydraulic capacities of 28,000 and 30,500 cfs, respectively.
Target elevations for Brownlee Reservoir define the flow of water through the HCC. However, when flows exceed powerhouse capacity for any of the projects, water is released over the spillways at those projects. When flows through the HCC are below hydraulic capacity, all three projects operate closely together to re-regulate flows through the Oxbow and Hells Canyon projects so that they remain within the 1-foot per hour ramp rate requirement (measured at Johnson Bar below Hells Canyon Dam) and still meet the daily peak load demands.
In addition to maintaining the ramp rate, IPC maintains minimum flow rates in the Snake River downstream of Hells Canyon Dam. These minimum flow rates are for navigation purposes and IPC’s compliance with article 43 of the existing license. Neither the Brownlee Project nor the Oxbow Project has a minimum flow requirement below its powerhouse. However, because of the Oxbow Project’s unique configuration, a flow of 100 cfs is maintained through the bypassed reach of the Snake River below the dam (a segment called the Oxbow Bypass).
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3.2. Seasonal Operations of Brownlee Reservoir
Brownlee Reservoir is a multiple-use, year-round resource for the Northwest. Although its primary purpose is providing a stable power source, Brownlee Reservoir is also used for flood control, fish and wildlife mitigation, and recreation.
Brownlee Dam is one of several Northwest dams that cooperate to provide springtime flood control on the lower Columbia River and, between 1995 and 2001, to regulate flow in the lower Snake River. For flood control, IPC operates the reservoir cooperatively with the U.S. Army Corps of Engineers (COE) North Pacific Division, according to article 42 of the existing license.
After flood-control requirements have been met in early summer, the reservoir is refilled to meet peak summer electricity demands and provide suitable habitat for spawning bass and crappie. The full reservoir also offers optimal recreational opportunities through the Fourth of July holiday.
As part of the flow augmentation reasonable and prudent alternative (RPA) implemented by the 1995 and 2000 FCRPS biological opinions, the Bureau of Reclamation (BOR) periodically releases water from BOR storage reservoirs in the upper Snake River to assist with the migration of anadromous fish past the lower Snake River FCRPS projects. From 1995 through the summer of 2001, IPC cooperated with the BOR and other federal interests in these flow augmentation efforts by shaping (or pre-releasing) water from Brownlee Reservoir (and later refilling the drafted reservoir space with water released by the BOR from the upper Snake River reservoirs) and by occasionally contributing water to flow augmentation efforts. To facilitate IPC’s cooperation with the flow augmentation RPA, in 1996 the Bonneville Power Administration (BPA) entered into an energy exchange agreement with IPC. The agreement reimbursed IPC for any energy losses it incurred as a result of the company’s participation through an energy exchange mechanism. That agreement expired in April 2001 and has not been renewed by BPA.
Later in the fall, Brownlee Reservoir’s releases are managed to maintain constant flows below Hells Canyon Dam. These flow requirements, which are based on the Fall Chinook Recovery Plan that IPC adopted in 1991, as well as the minimum flow required by article 43, help ensure sufficient water levels to protect even the shallowest spawning nests, or redds. After fall chinook spawn, IPC attempts to have a full reservoir by the first week of December to meet winter peak demands.
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4. METHODS
4.1. Sampling Design
4.1.1. Upstream Reach
The Upstream Reach extended along the Snake River from river mile (RM) 340 at Cobb Rapid on the Idaho and Oregon border to RM 395 below the confluence of the Boise and Owyhee rivers. For sampling, we divided the Upstream Reach into 19 subreaches of 5 river miles each using 1:24,000 USGS topographic maps (Figure 1 and Table 1). Because the USGS maps contain a “gap” in their river mile labels the subreach identified as RM 385-390 does not exist on the USGS maps. While this labeling error gives the appearance that our study design did not include a 5-mile subreach, our sampling was actually continuous throughout the entire upstream reach.
During June and July 1998, we collected 2 composite, macroinvertebrate samples within each five-mile subreach (Figure 4). Each of the 2 composites consisted of dredging efforts at 3 micro- sample sites. The 6 micro-sample sites within a subreach were located by randomly selecting 6 of the possible 50 tenths of river miles microsites within each 5-mile subreach. Selected micro- sample sites were then sequentially sampled from downstream to upstream. The first 3 microsites sampled within a subreach were considered one sample, while the second group of 3 microsites constituted the second sample.
At each micro-sample site, we dredged five 0.25 m2 areas over the range of accessible depths. The range of accessibility was defined by the length of the dredge hose. The boat was secured to the riverbank, and the range of depths within approximately 50 feet of the boat (the length of our dredge hose) were then sampled by collecting 5 dredges. Therefore, each sample contained macroinvertebrates collected from 5 dredging efforts at each of 3 microsites for a total of 15 dredge collections per sample (Figure 4). From each of the composite samples, 5 individual subsamples (jars) were then removed for taxonomic analysis. The 15-dredge composite was thoroughly mixed before removing the 5 subsamples.
4.1.2. Reservoir Reach
Six sample sites, two each in Brownlee, Oxbow, and Hells Canyon Reservoirs, were chosen for macroinvertebrate sampling (Figure 2). In Brownlee Reservoir, sample sites were established as fixed cross-sectional transects at RM 302.9 of the Snake River and RM 3.6 on the Powder River Arm. Transects were established at RM 274.0 and 279.0 of the Snake River in Oxbow Reservoir and at RM 263.0 and 265.5 in Hells Canyon Reservoir. Within each reservoir, we chose sites where transects had similar aquatic habitat, geology, and terrain.
Each transect extended perpendicularly across a reservoir from the high-water mark on one shoreline to the high-water mark on the opposite shoreline. Each transect was divided into a river-right and river-left shoreline micro-sample site. We collected subsamples of benthic
Hells Canyon Complex Page 11 Benthic Macroinvertebrates of Hells Canyon Idaho Power Company macroinvertebrates at depths of 1 m, 5 m, 10 m, and 15 m below the high-water mark during each season (winter, spring, summer, and fall) of 1998 and at each micro-sample site. Consequently, we collected 4 subsamples at each micro-sample site of each fixed transect, or 8 subsamples per sample site during each season (Figure 5) (Table 2).
Collection methods included dredging, Ponar, and benthic excavation. Benthic excavation was used only at dewatered sample sites and targeted stranded macroinvertebrates. Each collection was placed in a sample jar and represented a subsample from a micro-sample site.
4.1.3. Downstream Reach
Downstream of Hells Canyon Dam, we subdivided the reach into 58 1-river mile sections (i.e., RM 189 to 246) based on 1:24,000 USGS topographic maps (Figure 3). During January to May 1998 and between RM 189 and 219, we collected macroinvertebrates at 2 sample sites that, within a river mile, were each comprised of 3 micro-sample sites (Figure 6). We randomly selected tenth-river miles within each river mile section for establishing micro-sample sites. Macroinvertebrates were collected at each of the micro-sample sites. Selected micro-sample sites were then sampled sequentially from downstream to upstream over January−October.
At a randomly selected tenth-river mile, we visually assessed both shorelines for the feasibility and safety of collecting macroinvertebrates while wading and diving. We established individual micro-sample sites on shorelines where feasible. Specifically, 2 micro-sample sites could be established at one randomly selected tenth-river mile if both shores were accessible to sampling. Likewise, another tenth-river mile would be selected if neither shoreline were acceptable for sampling. We dredged five 0.25 m2 area macroinvertebrate collections from within each micro- sample site. An individual sample site was composed of the first 3 feasible micro-sample sites within a river mile. Correspondingly, the second sample site was composed of the second 3 micro-sample sites. Therefore, each river mile section contained 2 sample sites, and each sample site was comprised of 3 micro-sample sites. At each microsite, 5 dredge collections were taken, resulting in a total of 15 dredge collections per sample (Figure 6).
Dredges were collected only with wading between RM 188 and 201, because of unsafe, low- temperature diving conditions. Dredges were collected with both wading and scuba diving at the remaining sample sites from RM 201 upstream to Hells Canyon Dam.
As in the Upstream Reach, dredge collections from each sample site were combined into a single composite collection from which 5 composite subsamples were taken (Figure 6). The 15 dredge collections were thoroughly mixed in a bucket before selecting the 5 subsamples. We repeated the process at the second sample site within a river mile section for a total of 5 subsamples per sample site, and 2 individual samples per river mile.
Conversely, during September to October 1998, we only established 1 sample site per river mile between RM 219 (approximately Kirby Creek) and 247 (approximately Hells Canyon Dam). Similar to other samples, 5 dredges were collected for each micro-sample site and 3 micro- sample sites were collected for each sample site established within a river mile section. Consequently, only 1 independent sample was collected for each river mile section between RM 219 and 247 (Figure 6) (Table 1).
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4.2. Field Methods
Sampling methods varied throughout the course of the 1998 field season depending on conditions at the time of sampling. The primary sample collection method was suction dredging. Generally, divers using SCUBA gear operated the dredge except when the water was shallow enough for wading, or cold temperatures or high water velocities created safety hazards for divers. The Ponar dredge was only used in reservoirs when low water temperature precluded safe diving. Excavation with a shovel was used at the reservoir sites when the sampling location was dewatered at the time of sampling. Additional detail regarding sampling methods and protocols imposed within each of the reaches are described below.
4.2.1. Upstream Reach
All samples from RM 340−RM 395, were collected at micro-sample sites with a venturi loop vacuum dredging apparatus, sampling an area measuring 0.25 m2. Scuba-equipped divers were used when required by water depths. However, because of the relatively shallow, often braided nature of the Snake River channel within this reach, the majority of sample sites were accessible by wading. The contents of each dredging effort (subsample) were passed through a series of three sieves—2.5 mm, 1.0 mm, and 500 µm mesh size, in order to separate the majority of the substrate from the macroinvertebrates. Each subsample retained by this sieving process was then placed in a large, composite bucket. When the material from 15 dredging efforts, gathered from three sample microsites, had been combined in the composite bucket, the contents were thoroughly mixed and 5 subsamples were removed from the aggregate. These subsamples were preserved in 70% ethyl alcohol, and labeled in the field. After field collection of all samples was completed, the samples were sent to EcoAnalysts in Moscow, Idaho for taxonomic analysis. Once in the care of EcoAnalysts, a 100% sort and count of the invertebrates from each subsample was performed and all invertebrate specimens identified to the lowest possible taxonomic level. All specimens were then deposited with the Orma J. Smith Museum of Natural History in Caldwell, Idaho.
In the upstream reach, an effort was made to collect samples from varying depths at each micro- sample site. Therefore the depths of the five subsamples within each microsite were represented as a range, by documenting only the depths of the shallowest and deepest samples collected at each location. The substrate encountered at each dredge location was classified and recorded according to the Wentworth (1922) scale of geological classification. Furthermore, a Hydrolab Datasonde 3® was used to record the physical and chemical water quality parameters—including temperature, dissolved oxygen, pH, and specific conductivity within each five mile subsection of the reach.
4.2.2. Reservoir Reach
The basic sampling design developed for sampling the reservoirs within the HCC was designed to remain consistent with those used in the upstream reach, while taking into consideration the much greater depths associated with the reservoir environment. Six transect lines, spanning the entire channel, between the discernable high water marks on both banks were established on
Hells Canyon Complex Page 13 Benthic Macroinvertebrates of Hells Canyon Idaho Power Company
each reservoir. On these transect lines eight 0.25 m2 samples were collected, four from each side of the reservoir, at distances of 1, 5, 10 and 15 m from the visually discernable high water mark.
Because of variable water levels and temperatures encountered in the HCC reservoirs during repeat sampling visits in 1998, various sampling techniques were employed to collect invertebrate samples. Since the 1, 5, 10 and 15 m sampling distances on each transect were measured from full pool elevations, there were sampling events when water levels were such that as many as the first two - three sampling depths were desiccated during the time of sampling. For example, during sampling in August, Brownlee reservoir was down more than 30ft. below full pool. In desiccated sampling locations benthic samples were excavated with a shovel instead of the venturi loop dredge. Furthermore, on sampling visits when water temperatures were determined to be too cold for safe diving, such as in March when water temperatures were 42 °F, samples were collected using a petite Ponar dredge.
In the reservoirs, individual dredges were not combined into composite collections. Rather, each dredge was sieved and then placed in an individual subsample jars and uniquely labeled for laboratory analysis. These subsamples were preserved in 70% ethyl alcohol and labeled in the field for later identification by EcoAnalysts in Moscow, Idaho. Once in the care of EcoAnalysts, a 100% sort and count of the invertebrates from each subsample was performed and all invertebrate specimens identified to the lowest possible taxonomic level. All specimens were then deposited with the Orma J. Smith Museum of Natural History in Caldwell, Idaho.
4.2.3. Downstream Reach
Sampling began in January at the confluence of the Salmon River and progressed upstream. From RM 188 to RM 218, six random tenths were selected from each river mile. Five 0.25 m2 dredging efforts were collected from each of the first three of these random tenths (micro-sample sites) encountered as the crew progressed upstream, for a total of 15 samples. Material from each dredging effort (subsample) was passed through a series of three sieves—2.5 mm, 1.0 mm, and 500 µm mesh size, in order to separate the majority of the substrate from the macroinvertebrates. Each subsample retained by this sieving process was then placed in a large, composite bucket. When the material from 15 dredging efforts, gathered from three sample microsites, had been combined in the composite bucket, the contents were thoroughly mixed and 5 subsamples were removed from the aggregate. This process was then repeated for the remaining three tenth sections, for a total of ten samples per river mile. Two sites, or 10 dredging efforts (five of the samples from each 15 sample composite) were to be collected at depth, by SCUBA divers, per river mile. However cold water and high-river flows were unsafe for diving during January to March. Hence, cold water sampling was restricted to suction dredging while wading along shallow and protected shorelines, up to RM 201. By the time the crew reached this point in the river, water temperatures had warmed enough to allow for safe diving conditions.
On September 23rd, at RM 219 it was decided that a continuation of sampling under the current protocol would not allow adequate time for completion of the survey. Therefore sampling at six random tenths, or micro-sample sites per river mile, was reduced to three. From this point on, 15 subsamples were collected per river mile rather than 30. The 15 subsamples were collected dredging 5 points at three randomly selected tenth of river mile sites within each mile. Five of
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the 15 composite samples per RM were still collected at depth, by SCUBA equipped divers. The 15 subsamples were composited into one bucket. The contents of the bucket were then thoroughly mixed and five subsamples were removed from the aggregate and placed into individual jars. Each of the five jars containing material collected from every 1-mile segment of the reach, were uniquely labeled and preserved in 70% ethyl alcohol. Samples were sent to EcoAnalysts in Moscow, Idaho, where 100% of sample contents was sorted, enumerated, and identified to the lowest possible taxonomic level. Specimens were deposited with the Orma J. Smith Museum of Natural History in Caldwell, Idaho.
In response to the identification of a Bliss Rapids snail in one of the samples collected near Pine Bar during the 1998 survey, we conducted additional sampling in 2002. The snail collected during the 1998 survey was identified as a Bliss Rapids snail by EcoAnalysts, and then subsequently sent to Dr. Robert Hershler (Dept. of Systematic Biology, Smithsonian Institution, Washington, D.C.) for verification. In November 2002, the IPC invertebrate crew returned to the Snake River, near Pine Bar (RM 227) with the goal of collecting additional specimens to confirm the presence of T. serpenticola in the vicinity. On this occasion, sampling began approximately 1 mile downstream of Pine Bar (RM 226.5) and proceeded to a point approximately one half mile above Pine Bar (RM 228). Within this reach an effort was made to sample all available substrate and habitat. Information used in delineating sampling locations was gathered from IPC’s morphological and substrate classification maps (Chandler et al. 2001). Sixty-two, 0.25 m2 vacuum dredge collections were made throughout the reach. Each collection was run through a series three sieves—2.5 mm, 1.0 mm, and 500 µm mesh sieves to separate the majority of the substrate from the macroinvertebrates. The material retained in the sieves was then placed in white, flat-bottom pans and visually scanned for Bliss Rapids snails. When a Bliss Rapids snail was found it was recorded in the field log book and packaged live, for immediate shipment to Dr. Robert Hershler for positive identification. After Bliss Rapids snails were removed from the sample, the remaining material was returned to the river.
4.3. Data Analysis
4.3.1. Relative-abundance Index
We were unable to estimate macroinvertebrate densities because of the lack of quantitative subsampling, resulting in an unknown relationship of subsamples to composite samples. Therefore, for the upstream and downstream reaches we estimated a relative-abundance index by pooling data from subsamples from individual subreaches (e.g., 5-river mile subreaches upstream, 1-river mile subreaches downstream) and averaging data from the replicate samples collected within each subreach. The result is a relative abundance index that accounts for nonstandard sampling effort within a reach.
However, among reaches (e.g., upstream, reservoirs, or downstream) nonstandard sampling effort prevents reliable comparisons of index results. The confounding factor of sampling timing and seasonal life history of macroinvertebrates further precludes comparison among reaches. Because of quantification issues that precluded precision and accuracy estimates, the data is of unknown reliability. The sample size of 2 precluded reliability analyses within subreaches
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(Table 1). Comparisons within a reach must be made with caution because of these reasons and potentially unbalanced sampling effort.
Issues involving sampling design (e.g., changing water levels between events) and effort (e.g., variable collection methods between events) were more pervasive in reservoir sampling. Therefore, relative abundance indices were not estimated for this reach.
4.3.2. Sample Composition
Identification of individual macroinvertebrates to the lowest taxonomic level often results in inconsistent phylogeny at a particular level (e.g., not all individuals identified to genus or species level). Various reasons for this occur, including the condition of the sample, or life stage of particular organisms. To account for these inconsistencies, we reported sample composition at a taxonomic identification level that was consistent throughout, and accounted for all individuals identified (Table 3). Sample composition was estimated using the same process as described in the previous section for the analysis groups in (Table 3) and presented on a percentage scale. Further description of the samples in the form of common taxa (genus or species) are presented as that specific taxa’s percentage of the larger analysis group and includes only the individuals identified to lowest level. For example, Tricorythdes sp. as 50% of Ephemeroptera included only those individuals identified as Tricorythdes sp. and not individuals identified to the lowest level as Ephemeroptera, Tricorythidae or Tricorythodes.
5. RESULTS
5.1. Upstream Reach
Taxa found in samples collected in the upstream reach of the Snake River are listed in Appendix 1. For analysis, these taxa were grouped into levels where taxonomy was consistent and complete (Table 3). Of the 25 macroinvertebrate groups analyzed, the most common groups in the upstream samples were Ephemeroptera, Trichoptera, Diptera, Oligochaeta, and Gastropoda (Figure 7). Ephemeroptera was consistently the largest contributor to the sample and members of genus Tricorythodes were on average 75% of this group. Of the Trichoptera order, common species included members of the Hydropsychidae family. Hydropsyche was the most common Tricopteran, and was found in every 5-mile segment.
Percent Ephemeroptera and Trichoptera did not show any clear longitudinal patterns through the reach. However, patterns of change in other groups were apparent through the reach. Oligochaeta increased to approximately 13% of all organisms between RM 360 and RM 340 from less than 1% for the remainder of the reach (Figure 7). This increase in Oligochaeta was entirely due to increases in one species, Limnodrilus hoffmeisteri. Percent Diptera, over 94% of which were family chironomidae in the upstream reach, increased downstream of RM 355 compared to upstream of RM 355. Upstream of RM 355 Dipterans were generally low, at or below 10% of the sample (Figure 7).
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Relative abundance indices of the various taxa appeared variable with no, single, consistent longitudinal pattern (Figure 8). Several possible patterns include somewhat similar relative abundance upstream of the 365−370 subreach, followed by the highest relative abundance in the 365−370 subreach. The Payette River enters the Snake River in the 365−370 subreach. Relative abundance declined in subreaches below the Payette River, followed by an abrupt increase at the headwaters of Brownlee Reservoir.
Of special concern to us was the presence or absence of endangered or threatened snails, and the status of the New Zealand mudsnail (Potamopyrgus antipodarum). For this reason lower taxonomic levels of the Class Gastropoda were analyzed separately. We found Pyrgulopsis idahoensis (Idaho Springsnail) in only one 5-mile subreach. There it comprised 27% of the Gastropods collected (Table 4). The New Zealand mudsnail also occurred in the subreach containing Idaho Springsnails as well as in 3 additional subreaches. In one subreach (RM 350−355), it accounted for 100% of the Gastropods sampled.
5.2. Reservoir Reach
Taxa found in samples from the reservoirs were generally different from taxa found upstream (Appendix 2). Specifically, in the reservoirs more Oligochaetes were found than in the upstream samples. In addition, no Trichoptera, Plecoptera, or Tricorythodes (the most common Ephemeroptera upstream) were detected in the reservoir samples. Fewer taxa were found in Brownlee samples during all seasons (Table 5) compared to Oxbow (Table 6) and Hells Canyon (Table 7). Some seasonal patterns were evident with Cladocera appearing only in spring in Brownlee, and winter and spring in Oxbow and Hells Canyon. Bivalves were found in samples from all seasons in Oxbow and Hells Canyon but in no samples from Brownlee Reservoir. The Idaho Springsnail was not found in samples from the reservoirs, while the New Zealand mudsnail was found in Oxbow Reservoir during summer and fall sampling.
5.3. Downstream Reach
Sections of the downstream Snake River reach were sampled throughout 1998. The section extending from RM 219 upstream to RM 231 was sampled in the winter/spring of 1998 while the section from RM 231 upstream to RM 246 (Hells Canyon Dam) was sampled in fall 1998. Fall sampling extended from late September to the end of October. We were only able to compare sample composition from RM 219 through 247 because sampling at other locations was not conducted during a similar time period. Macroinvertebrate emergence and life history, and confounding factors such as flow, and water temperature precluded meaningful sample composition analysis among the entire range of sites sampled within the downstream reach.
Taxa found in samples taken during this fall time period are shown in Appendix 3. Taxa composition during October sampling varied longitudinally, with members of the Phylum Platyhelminthes very common in locations close to Hells Canyon Dam (Figure 9). All individuals in this analysis group were identified to the lowest level of class Turbellaria. Platyhelminthes and Bivalvia (Corbicula sp.) were very common approximately six miles downstream from the dam with significant numbers of Gastropods also present. Taxa
Hells Canyon Complex Page 17 Benthic Macroinvertebrates of Hells Canyon Idaho Power Company composition changed moving downstream from RM 236 to 231 with Oligochaeta becoming common (Figure 9). During October sampling (RM 246−231) the most common Oligochaeta taxa were family Enchytraeidae (average 75% of Oligochaeta) and Limnodrilus hoffmeisteri (average 21% of Oligochaeta).
Taxa composition in September samples was variable showing no clear longitudinal patterns. Member of the Platyhelminthes and Bivalvia were the same as October sampling while Oligochaeta members changed slightly to Enchytraeidae (average 86% of Oligochaeta) and Limnodrilus hoffmeisteri (average 13% of Oligochaeta) (Figure 10).
Relative abundance index for October sampling showed lower values below RM 239 and relatively high values closer to the dam when Platyhelminthes were abundant (Figure 11). Relative abundance index in September increased slightly in the downstream section during September sampling (Figure 12).
Idaho Springsnails were not found in samples collected below the dam. One Bliss Rapids snail was found in samples collected in the RM 227 subreach during the 1998 survey. Our sampling in November 2002, which was designed to target collection of additional Bliss Rapids snails resulted in collection of 3 individuals that were field identified as Bliss Rapids snails. Taxonomic identification of the three individuals collected in 2002 and sent to Dr. Hershler was inconclusive. He characterized some of the snails’ features as appearing to be more like Amnicola. His conclusion was that more specimens would be required to resolve the taxonomic uncertainty. The New Zealand mudsnail was found in half (14) of the 1-mile subreaches below Hells Canyon Dam (Table 8). Furthermore, of the 14 subreaches that contained New Zealand mudsnails, half (7) contained New Zealand mudsnail numbers that accounted for over 50% of the Gastropods collected. Ferissia sp.was the only Gastropod taxon more common than the New Zealand mudsnail
6. DISCUSSION
6.1. Upstream Reach
The Snake River valley and its watersheds in the upstream reach include some of the most urbanized, as well as most intensively farmed, areas in Idaho. Therefore, the potential for degraded water quality within this reach is high. Regardless of how obvious these water quality problems may seem, pinpointing their origins and specific effects on the aquatic ecosystem in the Snake River Basin remains a difficult task since water quality disturbances often have no single and apparent source (nonpoint source) and are episodic.
In this report of 1998 benthic macroinvertebrate sampling, assessing water quality problems using biomonitoring metrics is not possible because of lack of quantitative subsampling and unknown reliability (e.g., no precision, bias, or accuracy estimates) of the data. However, our results describing taxonomic composition agree with earlier macroinvertebrate studies contracted by IPC (McGuire 1991) who noted the largest component of the samples were Tricorythodes sp,
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Hydropsyche sp,Tubificid Oligochaetes, and Cricotopus sp. (Diptera). McGuire (1991) noted an increase in Hilsenhoff Biotic Index, designed to detect organic pollution, at River Miles 364.4 and 345.3. Our results show increasing proportions of Limnodrilus hoffmeisteri, a species known to increase in abundance with organic enrichment (Rosenberg and Resh 1992) in that subreach. Results from our study and McGuire (1991) agree and suggest increasing organic enrichment downstream of the Payette River confluence (RM 365.5). McGuire (1991) also noted that macroinvertebrate density appeared to be primarily regulated by substrate composition and hydrology in this upstream reach. In this study, habitat specific information (e.g., riffle or pool, substrate type) was lost by compositing and no a priori stratification according to actual river habitat types, so the relationship of these data to available river habitat is unclear. Therefore, we are unable to further relate macroinvertebrate relationships to the physical environment in the Upstream Reach.
The relative abundance index showed some patterns that may be related to tributary confluences. Higher values occurred near the confluence of the Payette (RM 365.5). However, loss of substrate and other habitat information does not allow probable causes of these patterns to be determined.
While the endangered Idaho springsnail is present in the Snake River immediately upstream of Brownlee Reservoir, it does not appear to be widely distributed throughout the reach we sampled. It should also be noted that Dr. Robert Hershler, author of the 1998 systematic review of Pyrgulopsis (Hershler 1998), now considers Pyrgulopsis idahoensis to not be a separate species, but combined with 3 other members of the Natricola clade within the single species Pyrgulopsis robusta (= Potmatiopsis robusta) (Hershler and Liu 2003). The New Zealand mudsnail also occurs in the reach. While it appears more widespread in its distribution within the reach than the Idaho springsnail, the New Zealand mudsnail does not appear to be ubiquitous within the reach.
6.2. Downstream Reach
Samples collected downstream of Hells Canyon Dam, particularily during October, were dominated by non-insect groups. Downstream changes in sample composition and relative abundance index were also apparent. In the eight river miles closest to the dam Platyhelmenthes (free-living flatworms) and Corbicula sp. were most common. Both of these groups subsist primarily on fine detritus from the substrate or water column, and may be an indication that detrital material leaving Hells Canyon Reservoir is providing a food source for these groups. However, rapid reproduction of Platyhelmenthes during detrital-rich fall outflow below reservoirs can occur because of the life cycle of this group. Rapid reproduction is possible for two reasons. First, Turbelarians are monoecious, meaning each individual has both male and female reproductive organs. Second, in addition to sexual reproduction, they can reproduce asexually by fragmentation. With the decrease of these groups downstream relative abundance indices are notably lower below RM 239.
It is tempting to relate these patterns in taxonomic composition and relative abundance indices to known water quality characteristics below Hells Canyon Dam. Dissolved oxygen and temperature of water leaving Hells Canyon Dam can change substantially over a one-month
Hells Canyon Complex Page 19 Benthic Macroinvertebrates of Hells Canyon Idaho Power Company period during the fall (Myers et al. 2001). Myers et al. (2002) noted dissolved oxygen in the penstock of Hells Canyon Powerhouse increasing from approximately 3 mg/L to 6 mg/L through September and October 1998. Temperatures decreased nearly 10 °C during the same time frame (Myers et al 2002). Since portions of the downstream reach were sampled during three different events in late September, early October, and late October, defensible relationships between the taxa reported here, and water quality gradients that may exist downstream cannot be made. Decreases in relative abundance indices, and changes in taxonomic composition from RM 238 to RM 231 found in our sampling cannot be attributed to a specific environmental factor. Observed longitudinal patterns may be related to a number of factors but confounding factors in this 1998 study preclude conclusions as to cause and effect. We lost the ability to relate the sample species composition to specific habitat information because the specific habitat information was lost by our compositing technique. Our inability to correlate species composition to available river habitat further confounds the interpretation.
Although sampling in this reach was relatively intense during 1998 several original study objectives for the Snake River below Hells Canyon Dam could not be addressed. Specifically, objectives related to bioassessment, community function, effects of flow fluctuations, and assessing macroinvertebrates as a food base were problematic. Macroinvertebrate abundance and community composition can change in response to a number of factors including current velocity, channel morphology, substrate type, and anthropogenic influences such as non-point sediment, nutrient, and pesticide loading. EPT richness (the number of Ephemeroptera, Plecoptera, and Trichoptera) is often used in determining the level of environmental stress the benthic community is experiencing. Higher numbers of EPT taxa are generally believed to indicate less stressed environments since the majority of the taxa within these orders are sensitive to pollution (Rosenberg and Resh 1992). In this report we did not assess bioindicator metrics, community function, or macroinvertebrate issues related to flow fluctuations. Our inability to address those was the result of loss of sample-specific habitat information because of the compositing technique and potential for bias associated with non random selection of sampling sites. Most problematic was our inability to associate specific habitat conditions with samples, including substrate type, or fluctuation characteristics at each sample. We also were unable to assess macroinvertebrates as a food base in this report because lack of quantitative subsampling precluded quantitative analysis of densities or biomass.
Taxonomic uncertainty precludes us from making a conclusive determination regarding the presence of Bliss Rapids snails downstream of Hells Canyon Dam. While presence of Bliss Rapids snails near Pine Bar appears unlikely it cannot be ruled out. Pine Bar is approximately 300 miles downstream of the closest known contemporary colony of Bliss Rapids snails. Still, the specimens we collected resembled Bliss Rapids snails in enough features that Dr. Hershler, was unable to make a definitive taxonomic determination. His uncertainty was in large part the result of our small sample size, and the techniques used to preserve the specimens.
7. ACKNOWLEDGMENTS
We wish to acknowledge Dianne Shinn for her efforts as principal investigator throughout much of this study. In addition, Brad Alcorn, Ron Piston, Tim Stuart, Barry Bean, and Mike
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Stephenson provided valuable expertise, effort, and assistance in field sample collection. Finally we also wish to thank Dr. C. Michael Falter, Frank Edelmann and Jesse Naymik for providing analysis and reporting expertise.
8. LITERATURE CITED
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Brusven, M. A., C. MacPhee, and R. Biggam. 1974. Benthic insects: effects of fluctuation on benthic insects. In: K. Bayha, C. Koski, editors. Anatomy of a river: an evaluation of water requirements for the Hells Canyon Reach of the middle Snake River. Pacific Northwest Basin Commission, Vancouver, WA. p. 67−84.
Chandler, J. A., S. Brink, S. K. Parkinson, and M. Butler. 2001. Hells Canyon instream flow assessment. In: Technical appendices for new license application: Hells Canyon Hydroelectric Project. Idaho Power, Boise, ID. Technical Report E.2.3-2.
Ebel, W. J., and C. H. Koski. 1968. Physical and chemical limnology of Brownlee Reservoir, 1962−64. Fishery Bulletin 67(2):295−335.
Fitzgerald, J. F. 1982. Geology and basalt stratigraphy of the Weiser embayment, west-central Idaho. In: B. Bonnichsen and R. M. Breckenridge, editors. Cenozoic geology of Idaho. Idaho Bureau of Mines and Geology, Moscow, ID. p. 103−128.
Goodnight, W. H. 1971. Angler use of fish harvest at Brownlee Reservoir limnological studies of Brownlee Reservoir. F-53-R-6 (Job V-a, Job V-b). 26 p.
Growns, I. O., and J. E. Growns. 2001. Ecological effects of flow regulation on macroinvertebrates and periphytic diatom assemblages in the Hawkesbury– Napean River, Australia. Regulated Rivers: Research and Management 17:275−293.
Hershler, R. 1998. A systematic review of the hydrobiid snails (Gastropoda: Rissooidea) of the Great Basin, western United States. PartI. Genus Pyrgulopsis. Veliger 41:1−132.
Hershler, R., and H. P. Lui, 2003. Taxonomic status of the Idaho springsnail (Pyrgulopsis idahoensis). Report to the U.S. Fish and Wildlife Service, and Barker, Rosholt & Simpson LLP, Boise, ID.
Kjelstrom, S. C. 1995. Streamflow gains and losses in the Snake River and ground-water budgets for the Snake River Plain, Idaho and Eastern Oregon. U.S. Geological Survey I 19.16:08-c.
Malde, H. E. 1965. Snake River plain. Princeton University Press, Princeton, NJ.
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Milligan, J. H., R. A. Lyman, C. M. Falter, E. E. Krumpe, and J. E. Carlson. 1983. Classification of Idaho’s freshwater lakes. Research project completion report. Idaho Water and Energy Resources Institute, University of Idaho, Moscow, ID.
Morgan, R. P. II, R. Jacobsen, S. B. Weisberg, L. A. McDowell, and H. T. Wilson. 1991. Effects of flow alteration on benthic macroinvertebrate communities below the Brighton Hydroelectric Dam. Journal of Freshwater Ecology 6(2):419−428.
Mullins, W. H. 1998. Biological assessment of the lower Boise River, October 1995 through January 1998, Ada and Canyon counties, Idaho. U.S. Department of the Interior, U.S. Geological Survey.
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Thomas, C. A., and N. P. Dion. 1974. Characteristics of streamflow and ground-water condition in the Boise River watershed. U.S. Geological Survey. Report No. USGS-WRD-74-043.
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Ward, J. V. 1976. Effects of flow patterns below large dam on stream benthos: a review. American Fisheries Society Symposium II p. 235−253.
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Page 24 Hells Canyon Complex Idaho Power Company Benthic Macroinvertebrates of Hells Canyon
Table 1. Benthic macroinvertebrate sample distribution in the two reaches below, and above, the Hells Canyon dams complex, lower Snake River, 1998.
Downstream Reach Micro- Sample sample Composite Composite True Subreach Dates Sites Sites Collections1 Collections Subsamples Samples Downstream (Hells Canyon Dam to Kirby Creek) RM 219 9/23 1 3 15 1 5 1 220 9/23 1 3 15 1 5 1 221 9/24 1 3 15 1 5 1 222 9/24 1 3 15 1 5 1 223 9/24 1 3 15 1 5 1 224 9/28 1 3 15 1 5 1 225 9/28 1 3 15 1 5 1 226 9/28 1 3 15 1 5 1 227 9/29 1 3 15 1 5 1 228 9/29 1 3 15 1 5 1 229 9/30 1 3 15 1 5 1 230 9/30 1 3 15 1 5 1 231 10/6 1 3 15 1 5 1 232 10/6 1 3 15 1 5 1 233 10/6 1 3 15 1 5 1 234 10/7 1 3 15 1 5 1 235 10/7 1 3 15 1 5 1 236 10/7 1 3 15 1 5 1 237 10/8 1 3 15 1 5 1 238 10/8 1 3 15 1 5 1 239 10/20 1 3 15 1 5 1 240 10/20 1 3 15 1 5 1 241 10/20 1 3 15 1 5 1 242 10/20 1 3 15 1 5 1 243 10/21 1 3 15 1 5 1 244 10/21 1 3 15 1 5 1 245 10/22 1 3 15 1 5 1 246 10/22 1 3 15 1 5 1 Upstream (RM 395 down to headwaters of Brownlee Reservoir) RM 340-345 6/23 2 6 30 2 10 2 345-350 623-24 2 6 30 2 10 2 350-355 6/24 2 6 30 2 10 2 355-360 6/25 2 6 30 2 10 2 360-365 6/29 2 6 30 2 10 2 365-370 6/29-30 2 6 30 2 10 2 370-375 6/30 2 6 30 2 10 2 375-380 7/6 2 6 30 2 10 2 380-385 76 2 6 30 2 10 2 385-3902 No Data No Data No Data No Data No Data No Data No Data 390-395 7/7 2 6 30 2 10 2 1 Collection method was a 0.25m2 Venturi loop suction dredge. 2 River miles 385-390 were not present on the USGS sampling maps. River mile 390 followed river mile 385 on the sampling maps, so these river miles, (391-394) though not represented on the maps, were in fact, sampled.
Hells Canyon Complex Page 25 Benthic Macroinvertebrates of Hells Canyon Idaho Power Company
Table 2. Benthic macroinvertebrate sample distribution in the reservoir reach of the Hells Canyon dams complex, lower Snake River, 1998.
Reservoir Reach (Brownlee, Oxbow, and Hells Canyon Reservoirs) Micro- Sample sample Collections Subsample True Sample Times Sites Sites 1 s Samples
Brownlee Reservoir Winter 2 4 15 15 2 Spring 2 4 16 16 2 Summer 2 4 13 13 2 Fall 2 4 15 15 2
Oxbow Reservoir Winter 2 4 16 16 2 Spring 2 4 16 16 2 Summer 2 4 16 16 2 Fall 2 4 16 16 2
Hells Canyon Reservoir Winter 2 4 16 16 2 Spring 2 4 16 16 2 Summer 2 4 16 16 2 Fall 2 4 16 16 2
1 Collection methods were a 0.25m2 Venturi loop suction dredge, Ponar dredge, and dry excavation.
Page 26 Hells Canyon Complex Idaho Power Company Benthic Macroinvertebrates of Hells Canyon
Table 3. Benthic macroinvertebrate taxa found in the upstream, reservoir, and downstream reaches of the lower Snake River, 1998.
Taxonomy Reach
Reservoir
Upstream (Brownlee, Downstream Oxbow, & Hells Phylum Class Order (RM 340-395) Canyon) (RM 189-247) Coelenterata Undetected Detected Detected
Platyhelminthes Detected Detected Detected
Nemertea Undetected Detected Undetected
Nematoda Detected Detected Detected
Nematomorpha Detected Detected Detected
Mollusca Bivalvia Detected Detected Detected Gastropoda Detected Detected Detected
Annelida Branchiobdellida Detected Undetected Hirudinea Detected Detected Detected Oligochaeta Detected Detected Detected Polychaeta Undetected Detected Detected
Arthropoda Arachnida Detected Detected Detected
Branchiopoda Cladocera Undetected Detected Detected
Malacostraca Amphipoda Detected Detected Detected Malacostraca Decapoda Undetected Undetected Detected Malacostraca Isopoda Detected Detected Detected
Maxillopoda Copepoda Undetected Detected Undetected
Ostracoda Undetected Detected Undetected
Insecta Coleoptera Detected Detected Detected Diptera Detected Detected Detected Ephemeroptera Detected Detected Detected Lepidoptera Detected Undetected Detected Odonata Detected Undetected Detected Plecoptera Detected Undetected Detected Trichoptera Detected Undetected Detected
Hells Canyon Complex Page 27 Benthic Macroinvertebrates of Hells Canyon Idaho Power Company
Table 4. Percent Gastropoda and relative abundance indices of selected molluscan taxa in the upstream reach (RM 340−395) above Brownlee Reservoir, 1998.
Family Ancylidae Planorbidae Hydrobiidae Hydrobiidae Hydrobiidae Undetermined
Genus/Species
Subreach Potamopyrgus Pyrgulopsis (RM) Ferrissia sp. Vorticifex effusa Fluminicola sp. antipodarum idahoensis Undetermined Subreach Relative Abundance Index 340-345 0.00 0.10 0.20 0.00 0.00 0.00 345-350 0.00 0.10 0.50 0.00 0.00 0.00 350-355 0.00 0.00 0.00 0.30 0.00 0.00 355-360 0.10 0.90 0.10 0.10 0.00 0.00 360-365 0.10 2.30 1.30 0.00 0.00 0.50 365-370 0.00 3.00 6.20 0.20 3.60 0.30 370-375 0.00 0.70 0.10 0.00 0.00 0.20 375-380 0.30 0.40 0.00 0.00 0.00 0.00 380-385 0.00 0.20 12.40 0.00 0.00 0.00 390-395 0.00 2.00 1.70 2.00 0.00 0.00 Subreach Community Composition (Percent of Gastropoda)
340-345 0.00% 33.33% 66.67% 0.00% 0.00% 0.00% 345-350 0.00% 16.67% 83.33% 0.00% 0.00% 0.00% 350-355 0.00% 0.00% 0.00% 100.00% 0.00% 0.00% 355-360 8.33% 75.00% 8.33% 8.33% 0.00% 0.00% 360-365 2.38% 54.76% 30.95% 0.00% 0.00% 11.90% 365-370 0.00% 22.56% 46.62% 1.50% 27.07% 2.26% 370-375 0.00% 70.00% 10.00% 0.00% 0.00% 20.00% 375-380 42.86% 57.14% 0.00% 0.00% 0.00% 0.00% 380-385 0.00% 1.59% 98.41% 0.00% 0.00% 0.00% 390-395 0.00% 35.09% 29.82% 35.09% 0.00% 0.00%
Page 28 Hells Canyon Complex Idaho Power Company Benthic Macroinvertebrates of Hells Canyon
Table 5. Benthic macroinvertebrate taxa found in the Brownlee Reservoir reach of the lower Snake River, 1998.
Brownlee 1998 Winter Spring Summer Fall
Enchytraeidae Acari Caecidotea sp. Glyptotendipes sp. Lumbriculidae Ameletus sp. Chironomus sp. Turbellaria Orthocladius sp. Chironomini Crangonyx sp. Paracladopelma sp. Chironomus sp. Dicrotendipes sp. Phaenopsectra sp. Cladocera Enchytraeidae Physa (Physella) sp. Copepoda Endochironomus sp. Tubificidae w/o cap setae Cricotopus sp. Glyptotendipes sp. Drunella doddsi Limnodrilus hoffmeisteri Enchytraeidae Physa (Physella) sp. Gammarus sp. Physidae Glyptotendipes sp. Procladius sp. Helobdella stagnalis Zaitzevia sp. Limnodrilus hoffmeisteri Nais variabilis Phaenopsectra sp. Polypedilum sp. Procladius sp. Tubificidae w/ cap setae
Hells Canyon Complex Page 29 Benthic Macroinvertebrates of Hells Canyon Idaho Power Company
Table 6. Benthic macroinvertebrate taxa found in the Oxbow Reservoir reach of the lower Snake River, 1998.
Oxbow 1998 Winter Spring Summer Fall
Aulodrilus pluriseta Caecidotea sp. Acari Aulodrilus pluriseta Caecidotea sp. Chironomus sp. Caecidotea sp. Caecidotea sp. Chironomini Cladocera Chironomus sp. Chironomus sp. Chironomus sp. Cladotanytarsus sp. Corbicula sp. Corbicula sp. Cladocera Copepoda Crangonyx sp. Crangonyx sp. Cladotanytarsus sp. Corbicula sp. Cryptochironomus sp. Dero nivea Corbicula sp. Cricotopus sp. Dicrotendipes sp. Dicrotendipes sp. Cricotopus sp. Cryptochironomus sp. Enchytraeidae Enchytraeidae Cryptochironomus sp. Dicrotendipes sp. Ferrissia sp. Endochironomus sp. Dero sp. Enchytraeidae Glyptotendipes sp. Ferrissia sp. Dicrotendipes sp. Gammarus sp. Harnischia sp. Gyraulus sp. Eukiefferiella sp. Glyptotendipes sp. Hirudinea Hirudinea Gammarus sp. Hyalella sp. Hyalella sp. Hyalella sp. Hirudinea Limnodrilus hoffmeisteri Ilyodrilus templetoni Limnodrilus hoffmeisteri Hydra sp. Manayunkia speciosa Limnodrilus hoffmeisteri Manayunkia speciosa Limnodrilus hoffmeisteri Nais bretscheri Lumbriculidae Nais behningi Manayunkia speciosa Nais variabilis Manayunkia speciosa Orthocladius sp. Nais bretscheri Ophidonais serpentina Nematoda Ostracoda Nais pardalis Orthocladius Complex Paratanytarsus sp. Physidae Orthocladius sp. Ostracoda Pisidium sp. Pisidium sp. Paracladopelma sp. Paracladopelma sp. Polypedilum sp. Polypedilum sp. Paratanytarsus sp. Paranais sp. Potamopyrgus antipodarum Potamopyrgus antipodarum Physa (Physella) sp. Paratanytarsus sp. Procladius sp. Procladius sp. Polypedilum sp. Phaenopsectra sp. Tubificidae w/ cap setae Tubificidae w/ cap setae Procladius sp. Physa (Physella) sp. Turbellaria Pseudochironomus sp. Pisidium sp. Tanytarsus sp. Polypedilum sp. Tubificidae w/ cap setae Procladius sp. Tubificidae w/o cap setae Prostoma sp. Turbellaria Pseudochironomus sp. Sphaeriidae Tanytarsus sp. Tubificidae w/ cap setae Turbellaria Vejdovskyella sp.
Page 30 Hells Canyon Complex Idaho Power Company Benthic Macroinvertebrates of Hells Canyon
Table 7. Benthic macroinvertebrate taxa found in the Hells Canyon Reservoir reach of the lower Snake River, 1998.
Hells Canyon 1998 Winter Spring Summer Fall Caecidotea sp. Acari Caecidotea sp. Caecidotea sp. Chironomus sp. Aulodrilus pluriseta Chironomus sp. Chironomus sp. Cladocera Caecidotea sp. Cladotanytarsus sp. Cladotanytarsus sp. Cladotanytarsus sp. Chironomini Corbicula sp. Corbicula sp. Corbicula sp. Chironomus sp. Crangonyx sp. Crangonyx sp. Cricotopus sp. Cladocera Cryptochironomus sp. Cryptochironomus sp. Cryptochironomus sp. Cladotanytarsus sp. Dicrotendipes sp. Dicrotendipes sp. Dero sp. Copepoda Enchytraeidae Enchytraeidae Diamesa sp. Corbicula sp. Endochironomus sp. Ferrissia sp. Dicrotendipes sp. Cricotopus sp. Ferrissia sp. Gyraulus sp. Enchytraeidae Cryptochironomus sp. Gammarus sp. Harnischia sp. Ferrissia sp. Dero nivea Gyraulus sp. Hirudinea Gammarus sp. Dicrotendipes sp. Hirudinea Hyalella sp. Hydra sp. Eclipidrilus sp. Hyalella sp. Limnodrilus hoffmeisteri Limnodrilus hoffmeisteri Enchytraeidae Limnodrilus hoffmeisteri Lumbriculidae Lumbriculidae Ferrissia sp. Lumbricina Manayunkia speciosa Manayunkia speciosa Gammarus sp. Lumbriculidae Nematoda Nais behningi Hydra sp. Manayunkia speciosa Prosimulium sp. Nais bretscheri Limnodrilus hoffmeisteri Ophidonais serpentina Simulium sp. Nais pardalis Manayunkia speciosa Paratanytarsus sp. Stenonema terminatum Nais sp. Nais behningi Physidae Stictochironomus sp. Nais variabilis Nais bretscheri Polypedilum sp. Tubificidae w/ cap setae Paracladopelma sp. Nais variabilis Tubificidae w/ cap setae Turbellaria Paratanytarsus sp. Nematomorpha Turbellaria Phaenopsectra sp. Ophidonais serpentina Vorticifex effusa Polypedilum sp. Paracladopelma sp. Stenonema terminatum Paranais sp. Tanytarsus sp. Paratanytarsus sp. Tubificidae w/ cap setae Phaenopsectra sp. Tubificidae w/o cap setae Physa (Physella) sp. Turbellaria Polypedilum sp. Procladius sp. Sphaeriidae Stempellinella sp. Tanytarsus sp. Tubificidae w/ cap setae Turbellaria Vejdovskyella comata Vejdovskyella sp.
Hells Canyon Complex Page 31 Benthic Macroinvertebrates of Hells Canyon Idaho Power Company
Table 8. Relative abundance indices of selected molluscan taxa in the downstream reach (RM 219−246), 1998.
Family Ancylidae Lymnaeidae Planorbidae Planorbidae Hydrobiidae Hydrobiidae Genus/Species Taylorconcha Potamopyrgus Subreach Ferrissia sp. serpenticola Gyraulus sp. Undetermined Fluminicola sp. antipodarum Subreach Relative Abundance Index
RM 219 0.20 0.00 0.00 0.00 0.20 0.00 220 0.00 0.00 0.00 0.00 0.00 0.40 221 0.60 0.00 0.00 0.00 0.00 0.00 222 3.00 0.00 0.00 0.00 0.00 0.40 223 1.20 0.00 0.00 0.00 0.00 0.00 224 0.40 0.00 0.00 0.00 0.00 0.20 225 3.20 0.00 0.00 0.00 0.00 0.40 226 0.00 0.00 0.00 0.00 0.00 0.20 227 0.20 0.20 0.00 0.00 0.00 0.40 228 0.00 0.00 0.00 0.00 0.00 0.20 229 0.00 0.00 0.00 0.00 0.00 0.00 230 1.20 0.00 0.00 0.00 0.00 0.00 231 0.00 0.00 0.00 0.00 0.00 0.00 232 0.20 0.00 0.00 0.00 0.00 1.00 233 0.00 0.00 0.00 0.00 0.00 0.00 234 0.00 0.00 0.00 0.00 0.00 0.00 235 0.00 0.00 0.00 0.00 0.00 0.00 236 0.40 0.00 0.00 0.00 0.00 0.20 237 0.20 0.00 0.00 0.00 0.00 0.00 238 0.00 0.00 0.00 0.00 0.00 0.00 239 0.60 0.00 0.00 0.00 0.00 0.00 240 0.80 0.00 0.00 0.00 0.00 14.20 241 0.20 0.00 0.00 0.00 0.00 0.00 242 4.20 0.00 0.00 0.00 0.00 0.20 243 0.80 0.00 0.00 0.00 0.00 0.00 244 7.00 0.00 0.40 0.00 0.00 9.00 245 11.00 0.00 0.60 0.40 0.00 5.20 246 9.60 0.00 0.20 0.00 0.00 16.40
Page 32 Hells Canyon Complex Idaho Power Company Benthic Macroinvertebrates of Hells Canyon
Table 9. Percent Gastropoda of selected molluscan taxa in the downstream reach (RM 219−246) below Hells Canyon Reservoir, lower Snake River, 1998.
Family Ancylidae Lymnaeidae Planorbidae Planorbidae Hydrobiidae Hydrobiidae Genus/Species Taylorconcha Potamopyrgus Subreach Ferrissia sp. serpenticola Gyraulus sp. Undetermined Fluminicola sp. antipodarum Subreach Percent of Gastropoda
RM 219 50.00% 0.00% 0.00% 0.00% 50.00% 0.00% 220 0.00% 0.00% 0.00% 0.00% 0.00% 100.00% 221 100.00% 0.00% 0.00% 0.00% 0.00% 0.00% 222 88.24% 0.00% 0.00% 0.00% 0.00% 11.76% 223 100.00% 0.00% 0.00% 0.00% 0.00% 0.00% 224 66.67% 0.00% 0.00% 0.00% 0.00% 33.33% 225 88.89% 0.00% 0.00% 0.00% 0.00% 11.11% 226 0.00% 0.00% 0.00% 0.00% 0.00% 100.00% 227 25.00% 25.00% 0.00% 0.00% 0.00% 50.00% 228 0.00% 0.00% 0.00% 0.00% 0.00% 100.00% 229 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 230 100.00% 0.00% 0.00% 0.00% 0.00% 0.00% 231 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 232 16.67% 0.00% 0.00% 0.00% 0.00% 83.33% 233 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 234 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 235 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 236 66.67% 0.00% 0.00% 0.00% 0.00% 33.33% 237 100.00% 0.00% 0.00% 0.00% 0.00% 0.00% 238 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 239 100.00% 0.00% 0.00% 0.00% 0.00% 0.00% 240 5.33% 0.00% 0.00% 0.00% 0.00% 94.67% 241 100.00% 0.00% 0.00% 0.00% 0.00% 0.00% 242 95.45% 0.00% 0.00% 0.00% 0.00% 4.55% 243 100.00% 0.00% 0.00% 0.00% 0.00% 0.00% 244 42.68% 0.00% 2.44% 0.00% 0.00% 54.88% 245 63.95% 0.00% 3.49% 2.33% 0.00% 30.23% 246 36.64% 0.00% 0.76% 0.00% 0.00% 62.60%
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Sleepy C ou 217 g h a RM 219 C r o r 218 ra L h l i g Creek Triangle Cr. h tn C h Kirby Mtn i r n e g Salt e 220 k h Kirkwood C 221 r. h Historic 3@ Creek Cr. 222 Ranch h K Imnaha 223 irk h wo Creek od 224 h Creek C r e e k ce 225 n hC ra a e ribo p 226 u m h e T 227 Creek h
River 228 h H o R r s u Fork e s 229 h h Sh Clarks 230 e h ep Cr. 231 S l h uic C r. e 232
a h
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Creek
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a
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t
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C 246 h C r e e 247Hells k Hells Canyon Cr. h Canyon t Rec. Site ich i m 248 Dam R h m Su Features Legend Tech. Report E.3.1-8 Figure 3 Vicinity Map HELLS CANYON HYDROELECTRIC COMPLEX Washington Streams Note: Highlighted river miles reflect a change in sampling protocal. Montana Secondary Route l Hells Canyon l Oxbow Brownlee Primary Route Downstream Study Area Oregon Idaho Water Body Wyoming Urban Areas Nevada Utah h River Mile
Ê 03691.5 Miles Benthic Macroinvertebrates of Hells Canyon Idaho Power Company
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Page 40 Hells Canyon Complex Idaho Power Company Benthic Macroinvertebrates of Hells Canyon
Composite Subreach (5 Sample Sample Collection River Miles) Site Microsite Dredge (Bucket) Composite Subsamples (Jar) 1 2 13 4 5 1 2 123 1 ABCDE 4 5 1 2 33 4 15 (340-345) 1 2 13 4 5 1 2 223 1 ABCDE 4 5 1 2 33 4 5
Figure 4. Example schematic showing sample design and subsampling process for a 5-river mile subreach in the upstream reach.
Hells Canyon Complex Page 41 Benthic Macroinvertebrates of Hells Canyon Idaho Power Company
Sample Sample Subsample Subreach Site Microsite Collections (Jar) 1A Right 2 B Bank 3 C Transect 4 D 11A Left 2 B Bank 3 C Brownlee 4 D 1A Right 2 B Bank 3 C Transect 4 D 21A Left 2 B Bank 3 C 4D 1A
Figure 5. Example schematic showing sample design and subsampling process for a transect sampling in the reservoir reach.
Page 42 Hells Canyon Complex Idaho Power Company Benthic Macroinvertebrates of Hells Canyon
Composite Sample Sample Sample Site Microsite Collection (Bucket) Subsample (Jar) 1 2 13 4 5 1 2 12 3 1ABCDE RM 245) 4 5 1 2 33 4 5
Figure 6. Example schematic showing sample design and subsamplng process sampling in the downstream reach.
Hells Canyon Complex Page 43 Benthic Macroinvertebrates of Hells Canyon Idaho Power Company
100%
90%
80% n 70%
60%
50%
40%
30% Taxonomic Compositio Taxonomic
20%
10%
0% Cobb 340-345 345-350 350-355 355-360 360-365 365-370 370-375 375-380 380-385 390-395 Boise Rapid River Subreach
Diptera Ephemeroptera Gastropoda Oligochaeta Trichoptera
Note: Only groups comprising greater than 5% of the samples at one or more subreach are shown
Figure 7. Taxonomic composition of analysis groups for samples collected in the upstream reach.
Page 44 Hells Canyon Complex Idaho Power Company Benthic Macroinvertebrates of Hells Canyon
200
180
160 x 140
120
100
80
60 Relative Abundance Inde Abundance Relative 40
20
0 Cobb 340-345 345-350 350-355 355-360 360-365 365-370 370-375 375-380 380-385 390-395 Boise Rapid River Subreach
Diptera Ephemeroptera Gastropoda Oligochaeta Trichoptera
Note: Only groups comprising greater than 5% of the samples at one or more subreach are shown
Figure 8. Relative abundance index for samples collected in the upstream reach.
Hells Canyon Complex Page 45 Benthic Macroinvertebrates of Hells Canyon Idaho Power Company
100%
90%
n 80%
70%
60%
50%
40%
30%
Taxonomic Compositio Taxonomic 20%
10% 0%
1 3 5 231 232 233 234 235 236 237 238 239 240 24 242 24 244 24 246 Dam n
Canyo
Hells Subreach
Amphipoda Bivalvia Diptera Ephemeroptera Gastropoda Lepidoptera
Nematoda Oligochaeta Platyhelminthes Trichoptera
Note: Only groups comprising greater than 5% of the samples at one or more subreach are shown
Figure 9. Taxonomic composition for samples collected during October in the downstream reach.
Page 46 Hells Canyon Complex Idaho Power Company Benthic Macroinvertebrates of Hells Canyon
220 200
x 180 160 140 120 100 80 60
Relative Abundance Inde Abundance Relative 40 20 0
4 6 8 231 232 233 23 235 23 237 23 239 240 241 242 243 244 245 246
Hells Canyon Dam Subreach
Amphipoda Bivalvia Diptera Ephemeroptera Gastropoda Lepidoptera
Nematoda Oligochaeta Platyhelminthes Trichoptera
Note: Only groups comprising greater than 5% of the samples at one or more subreach are shown
Figure 10. Relative abundance index for samples collected during October in the downstream reach.
Hells Canyon Complex Page 47 Benthic Macroinvertebrates of Hells Canyon Idaho Power Company
100%
90%
80% n 70%
60%
50%
40%
30% Taxonomic Compositio
20%
10%
0% Kirby 219 220 221 222 223 224 225 226 227 228 229 230 Creek Subreach
Amphipoda Bivalvia Diptera Ephemeroptera Gastropoda Lepidoptera
Nematoda Oligochaeta Platyhelminthes Trichoptera
Note: Only groups comprising greater than 5% of the samples at one or more subreach are shown
Figure 11. Taxonomic composition for samples collected during September in the downstream reach.
Page 48 Hells Canyon Complex Idaho Power Company Benthic Macroinvertebrates of Hells Canyon
220
200
180 x 160
140
120
100
80
60 Relative Abundance Inde Abundance Relative 40
20
0 Kirby 219 220 221 222 223 224 225 226 227 228 229 230 Creek Subreach
Amphipoda Bivalvia Diptera Ephemeroptera Gastropoda Lepidoptera
Nematoda Oligochaeta Platyhelminthes Trichoptera
Note: Only groups comprising greater than 0.5% of the samples at one or more subreach are shown
Figure 12. Relative abundance index for samples collected during September in the downstream reach.
Hells Canyon Complex Page 49 Benthic Macroinvertebrates of Hells Canyon Idaho Power Company
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Page 50 Hells Canyon Complex Idaho Power Company Benthic Macroinvertebrates of Hells Canyon
Appendix 1. Taxa breakdown of taxa indentified from the upstream reach (RM 340−RM 395).
Phylum Class Order Family Genus Taxa Codes
Upstream Taxa Sampled - RM 340-395
Branchiobdellida Undetermined Undetermined Undetermined Branchiobdellida Annelida Hirudinea Arhynchobdellida Erpobdellidae Undetermined Erpobdellidae Undetermined Undetermined Undetermined Hirudinea Oligochaeta Haplotaxida Enchytraeidae Undetermined Enchytraeidae Naididae Ophidonais Ophidonais serpentina Tubificidae Limnodrilus Limnodrilus hoffmeisteri Lumbricina Undetermined Undetermined Lumbricina Arthropoda Arachnida Undetermined Undetermined Undetermined Acari Insecta Coleoptera Elmidae Dubiraphia Dubiraphia sp. Microcylloepus Microcylloepus sp. Stenelmis Stenelmis sp. Undetermined Elmidae Diptera Ceratopogonidae Undetermined Ceratopogoninae Empididae Hemerodromia Hemerodromia sp. Simuliidae Simulium Simulium sp. Undetermined Simuliidae Tipulidae Undetermined Tipulidae Diptera-Chironomidae Chironomidae Chironomus Chironomus sp. Cladotanytarsus Cladotanytarsus (Lenziella) sp. Cladotanytarsus sp. Cricotopus Cricotopus bicinctus gr. Cricotopus sp. Cryptochironomus Cryptochironomus sp. Cryptotendipes Cryptotendipes sp.
Hells Canyon Complex Page 51 Benthic Macroinvertebrates of Hells Canyon Idaho Power Company
Phylum Class Order Family Genus Taxa Codes
Upstream Taxa Sampled - RM 340-395
Dicrotendipes Dicrotendipes sp. Endochironomus Endochironomus sp. Glyptotendipes Glyptotendipes sp. Harnischia Harnischia sp. Micropsectra Micropsectra sp. Microtendipes Microtendipes pedellus gr. Nanocladius Nanocladius sp. Odontomesa Odontomesa sp. Orthocladius Orthocladius obumbratus Orthocladius sp. Parachironomus Parachironomus sp. Paracladopelma Paracladopelma sp. Parakiefferiella Parakiefferiella sp. Paratanytarsus Paratanytarsus sp. Phaenopsectra Phaenopsectra sp. Polypedilum Polypedilum sp. Potthastia Potthastia longimana gr. Rheotanytarsus Rheotanytarsus sp. Robackia Robackia demeijerei Stempellinella Stempellinella sp. Stenochironomus Stenochironomus sp. Synorthocladius Synorthocladius sp. Tanytarsus Tanytarsus sp. Thienemannimyia Thienemannimyia gr. sp. Undetermined Chironomini Xenochironomus Xenochironomus sp.
Page 52 Hells Canyon Complex Idaho Power Company Benthic Macroinvertebrates of Hells Canyon
Phylum Class Order Family Genus Taxa Codes
Upstream Taxa Sampled - RM 340-395
Ephemeroptera Baetidae Acentrella Acentrella insignificans Acentrella sp. Acentrella turbida Baetis Baetis sp. Baetis tricaudatus Baetodes Baetodes sp. Camelobaetidius Camelobaetidius sp. Undetermined Baetidae Caenidae Caenis Caenis sp. Cercobrachys Cercobrachys sp. Undetermined Caenidae Ephemerellidae Attenella Attenella margarita Attenella sp. Ephemerella Ephemerella inermis/infrequens Heptageniidae Nixe Nixe sp. Rhithrogena Rhithrogena sp. Stenonema Stenonema terminatum Undetermined Heptageniidae Polymitarcyidae Ephoron Ephoron sp. Tricorythidae Tricorythodes Tricorythodes sp. Lepidoptera Pyralidae Petrophila Petrophila sp. Odonata Gomphidae Undetermined Gomphidae Plecoptera Perlodidae Cultus Cultus sp. Isoperla Isoperla sp. Skwala Skwala sp. Trichoptera Brachycentridae Brachycentrus Brachycentrus occidentalis
Hells Canyon Complex Page 53 Benthic Macroinvertebrates of Hells Canyon Idaho Power Company
Phylum Class Order Family Genus Taxa Codes
Upstream Taxa Sampled - RM 340-395
Glossosomatidae Culoptila Culoptila sp. Protoptila Protoptila sp. Hydropsychidae Cheumatopsyche Cheumatopsyche sp. Hydropsyche Hydropsyche sp. Undetermined Hydropsychidae Leptoceridae Nectopsyche Nectopsyche sp. Oecetis Oecetis avara Undetermined Leptoceridae Malacostraca Amphipoda Crangonyctidae Crangonyx Crangonyx sp. Gammaridae Gammarus Gammarus sp. Talitridae Hyalella Hyalella sp. Undetermined Undetermined Amphipoda Isopoda Asellidae Caecidotea Caecidotea sp. Mollusca Bivalvia Veneroida Corbiculidae Corbicula Corbicula sp. Sphaeriidae Pisidium Pisidium sp. Gastropoda Basommatophora Ancylidae Ferrissia Ferrissia sp. Planorbidae Vorticifex Vorticifex effusa Neotaenioglossa Hydrobiidae Fluminicola Fluminicola sp. Potamopyrgus Potamopyrgus antipodarum Pyrgulopsis Pyrgulopsis idahoensis Undetermined Undetermined Undetermined Gastropoda Nematoda Undetermined Undetermined Undetermined Undetermined Nematoda Nematomorpha Undetermined Undetermined Undetermined Undetermined Nematomorpha Platyhelminthes Turbellaria Undetermined Undetermined Undetermined Turbellaria
Page 54 Hells Canyon Complex Idaho Power Company Benthic Macroinvertebrates of Hells Canyon
Appendix 2. Taxa list and phylogeny for taxa identified in the reservoir reach during all seasons.
Phylum Class Order Family Genus Taxa Codes
Reservoir Taxa Sampled - Brownlee, Oxbow, Hells Canyon
Annelida Hirudinea Rhynchobdellida Glossiphoniidae Helobdella Helobdella stagnalis Undetermined Undetermined Undetermined Hirudinea Oligochaeta Haplotaxida Enchytraeidae Undetermined Enchytraeidae Naididae Dero Dero nivea Dero sp. Nais Nais behningi Nais bretscheri Nais pardalis Nais sp. Nais variabilis Ophidonais Ophidonais serpentina Paranais Paranais sp. Vejdovskyella Vejdovskyella comata Vejdovskyella sp. Tubificidae Aulodrilus Aulodrilus pluriseta Eclipidrilus Eclipidrilus sp. Ilyodrilus Ilyodrilus templetoni Limnodrilus Limnodrilus hoffmeisteri Undetermined Tubificidae w/ cap setae Tubificidae w/o cap setae Lumbricina Undetermined Undetermined Lumbricina Lumbriculida Lumbriculidae Undetermined Lumbriculidae Polychaeta Canalipalpata Sabellidae Manayunkia Manayunkia speciosa Arthropoda Arachnida Undetermined Undetermined Undetermined Acari Branchiopoda Cladocera Undetermined Undetermined Cladocera
Hells Canyon Complex Page 55 Benthic Macroinvertebrates of Hells Canyon Idaho Power Company
Phylum Class Order Family Genus Taxa Codes
Reservoir Taxa Sampled - Brownlee, Oxbow, Hells Canyon
Insecta Coleoptera Elmidae Zaitzevia Zaitzevia sp. Diptera Simuliidae Prosimulium Prosimulium sp. Simulium Simulium sp. Diptera-Chironomidae Chironomidae Chironomus Chironomus sp. Cladotanytarsus Cladotanytarsus sp. Cricotopus Cricotopus sp. Cryptochironomus Cryptochironomus sp. Diamesa Diamesa sp. Dicrotendipes Dicrotendipes sp. Endochironomus Endochironomus sp. Eukiefferiella Eukiefferiella sp. Glyptotendipes Glyptotendipes sp. Harnischia Harnischia sp. Orthocladius Orthocladius Complex Orthocladius sp. Paracladopelma Paracladopelma sp. Paratanytarsus Paratanytarsus sp. Phaenopsectra Phaenopsectra sp. Polypedilum Polypedilum sp. Procladius Procladius sp. Pseudochironomus Pseudochironomus sp. Stempellinella Stempellinella sp. Stictochironomus Stictochironomus sp. Tanytarsus Tanytarsus sp. Undetermined Chironomini Ephemeroptera Ameletidae Ameletus Ameletus sp.
Page 56 Hells Canyon Complex Idaho Power Company Benthic Macroinvertebrates of Hells Canyon
Phylum Class Order Family Genus Taxa Codes
Reservoir Taxa Sampled - Brownlee, Oxbow, Hells Canyon
Ephemerellidae Drunella Drunella doddsi Heptageniidae Stenonema Stenonema terminatum Malacostraca Amphipoda Crangonyctidae Crangonyx Crangonyx sp. Gammaridae Gammarus Gammarus sp. Talitridae Hyalella Hyalella sp. Isopoda Asellidae Caecidotea Caecidotea sp. Maxillopoda Copepoda Undetermined Undetermined Copepoda Ostracoda Undetermined Undetermined Undetermined Ostracoda Coelenterata Hydrozoa Hydroida Hydridae Hydra Hydra sp. Mollusca Bivalvia Veneroida Corbiculidae Corbicula Corbicula sp. Sphaeriidae Pisidium Pisidium sp. Undetermined Sphaeriidae Gastropoda Basommatophora Ancylidae Ferrissia Ferrissia sp. Physidae Physa Physa (Physella) sp. Undetermined Physidae Planorbidae Gyraulus Gyraulus sp. Vorticifex Vorticifex effusa Neotaenioglossa Hydrobiidae Potamopyrgus Potamopyrgus antipodarum Nematoda Undetermined Undetermined Undetermined Undetermined Nematoda Nematomorpha Undetermined Undetermined Undetermined Undetermined Nematomorpha
Nemertea Enopla Hoplonemertea Tetrastemmatidae Prostoma Prostoma sp. Platyhelminthes Turbellaria Undetermined Undetermined Undetermined Turbellaria
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Appendix 3. Taxa list and phylogeny for taxa detected in the downstream reach (RM 219−RM 247).
Phylum Class Order Family Genus Taxa Codes
Downstream Taxa Sampled - RM 219-247
Annelida Hirudinea Rhynchobdellida Piscicolidae Piscicola Piscicola sp. Undetermined Undetermined Undetermined Hirudinea Oligochaeta Haplotaxida Enchytraeidae Undetermined Enchytraeidae Naididae Nais Nais behningi Nais bretscheri Nais sp. Nais variabilis Spirosperma Spirosperma sp. Tubificidae Limnodrilus Limnodrilus hoffmeisteri Lumbricina Undetermined Undetermined Lumbricina Polychaeta Canalipalpata Sabellidae Manayunkia Manayunkia speciosa Arthropoda Arachnida Undetermined Undetermined Undetermined Acari Branchiopoda Cladocera Undetermined Undetermined Cladocera Crustacea Undetermined Undetermined Undetermined Crustacea Insecta Coleoptera Elmidae Cleptelmis Cleptelmis addenda Optioservus Optioservus sp. Zaitzevia Zaitzevia sp. Diptera Blephariceridae Undetermined Blephariceridae Empididae Chelifera Chelifera sp. Sciaridae Undetermined Sciaridae Simuliidae Simulium Simulium sp. Undetermined Simuliidae Tipulidae Antocha Antocha sp. Dicranota Dicranota sp. Undetermined Tipulidae
Hells Canyon Complex Page 59 Benthic Macroinvertebrates of Hells Canyon Idaho Power Company
Phylum Class Order Family Genus Taxa Codes
Downstream Taxa Sampled - RM 219-247
Undetermined Undetermined Diptera Diptera-Chironomidae Chironomidae Brillia Brillia sp. Cardiocladius Cardiocladius sp. Cladotanytarsus Cladotanytarsus (Lenziella) sp. Cladotanytarsus sp. Cricotopus Cricotopus (Cricotopus) sp. Cricotopus (Isocladius) sp. Cricotopus (Isocladius) Type I Cricotopus bicinctus gr. Cricotopus sp. Cricotopus tremulus gr. Cricotopus trifascia gr. Diamesa Diamesa sp. Dicrotendipes Dicrotendipes sp. Endochironomus Endochironomus sp. Eukiefferiella Eukiefferiella claripennis gr. Eukiefferiella devonica gr. Eukiefferiella sp. Heleniella Heleniella sp. Limnophyes Limnophyes sp. Micropsectra Micropsectra sp. Nanocladius Nanocladius sp. Odontomesa Odontomesa sp. Orthocladius Orthocladius (Euortho.) luteipes Orthocladius (Euortho.) rivicola gr. Orthocladius (Euorthocladius) sp.
Page 60 Hells Canyon Complex Idaho Power Company Benthic Macroinvertebrates of Hells Canyon
Phylum Class Order Family Genus Taxa Codes
Downstream Taxa Sampled - RM 219-247
Orthocladius (Orthocladius) sp. Orthocladius Complex Orthocladius obumbratus Orthocladius sp. Parametriocnemus Parametriocnemus sp. Phaenopsectra Phaenopsectra sp. Polypedilum Polypedilum sp. Pseudochironomus Pseudochironomus sp. Pseudosmittia Pseudosmittia sp. Rheocricotopus Rheocricotopus sp. Rheotanytarsus Rheotanytarsus exiguus gr. Rheotanytarsus sp. Smittia Smittia sp. Tanytarsus Tanytarsus sp. Tvetenia Tvetenia bavarica gr. Tvetenia sp. Tvetenia vitracies gr. Undetermined Orthocladiinae Ephemeroptera Ameletidae Ameletus Ameletus sp. Baetidae Acentrella Acentrella insignificans Acentrella sp. Baetis Baetis bicaudatus/tricaudatus Baetis sp. Baetis tricaudatus Diphetor Diphetor hageni Undetermined Baetidae
Hells Canyon Complex Page 61 Benthic Macroinvertebrates of Hells Canyon Idaho Power Company
Phylum Class Order Family Genus Taxa Codes
Downstream Taxa Sampled - RM 219-247
Ephemerellidae Drunella Drunella coloradensis/flavilinea Ephemerella Ephemerella inermis/infrequens Undetermined Ephemerellidae Heptageniidae Cinygmula Cinygmula sp. Heptagenia Heptagenia sp. Nixe Nixe sp. Rhithrogena Rhithrogena sp. Stenonema Stenonema terminatum Undetermined Heptageniidae Leptophlebiidae Paraleptophlebia Paraleptophlebia sp. Tricorythidae Tricorythodes Tricorythodes sp. Lepidoptera Pyralidae Petrophila Petrophila sp. Odonata Cordulegasteridae Cordulegaster Cordulegaster sp. Plecoptera Chloroperlidae Sweltsa Sweltsa sp. Undetermined Chloroperlidae Leuctridae Undetermined Leuctridae Nemouridae Malenka Malenka sp. Podmosta Podmosta sp. Zapada Zapada cinctipes Zapada columbiana Taeniopterygidae Undetermined Taeniopterygidae Undetermined Undetermined Plecoptera Trichoptera Hydropsychidae Cheumatopsyche Cheumatopsyche sp. Hydropsyche Hydropsyche sp. Undetermined Hydropsychidae Hydroptilidae Leucotrichia Leucotrichia sp.
Page 62 Hells Canyon Complex Idaho Power Company Benthic Macroinvertebrates of Hells Canyon
Phylum Class Order Family Genus Taxa Codes
Downstream Taxa Sampled - RM 219-247
Lepidostomatidae Lepidostoma Lepidostoma sp. Leptoceridae Ceraclea Ceraclea sp. Limnephilidae Undetermined Limnephilidae Malacostraca Amphipoda Crangonyctidae Crangonyx Crangonyx sp. Gammaridae Gammarus Gammarus sp. Talitridae Hyalella Hyalella sp. Decapoda Astacidae Pacifastacus Pacifastacus leniusculus Isopoda Asellidae Caecidotea Caecidotea sp. Coelenterata Hydrozoa Hydroida Hydridae Hydra Hydra sp. Mollusca Bivalvia Veneroida Corbiculidae Corbicula Corbicula sp. Gastropoda Basommatophora Ancylidae Ferrissia Ferrissia sp. Lymnaeidae Taylorconcha Taylorconcha serpenticola Physidae Physa Physa (Physella) sp. Planorbidae Gyraulus Gyraulus sp. Undetermined Planorbidae Vorticifex Vorticifex effusa Neotaenioglossa Hydrobiidae Fluminicola Fluminicola sp. Potamopyrgus Potamopyrgus antipodarum Undetermined Hydrobiidae Nematoda Undetermined Undetermined Undetermined Undetermined Nematoda Nematomorpha Undetermined Undetermined Undetermined Undetermined Nematomorpha Platyhelminthes Turbellaria Undetermined Undetermined Undetermined Turbellaria
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Appendix 4. Taxa list and phylogeny for taxa detected in the downstream reach during winter and spring sampling (RM 189−RM 219).
Phylum Class Order Family Genus Taxa Codes
Downsteam Taxa Sampled: RM 189-219
Annelida Hirudinea Rhynchobdellida Piscicolidae Piscicola Piscicola sp. Undetermined Undetermined Undetermined Hirudinea Oligochaeta Haplotaxida Enchytraeidae Undetermined Enchytraeidae Naididae Nais Nais bretscheri Nais sp. Nais variabilis Tubificidae Limnodrilus Limnodrilus hoffmeisteri Lumbricina Undetermined Undetermined Lumbricina Arthropoda Arachnida Undetermined Undetermined Undetermined Acari Branchiopoda Cladocera Undetermined Undetermined Cladocera Crustacea Undetermined Undetermined Undetermined Crustacea Insecta Coleoptera Elmidae Cleptelmis Cleptelmis addenda Zaitzevia Zaitzevia sp. Diptera Empididae Chelifera Chelifera sp. Sciaridae Undetermined Sciaridae Simuliidae Simulium Simulium sp. Undetermined Simuliidae Tipulidae Dicranota Dicranota sp. Undetermined Tipulidae Undetermined Undetermined Diptera Diptera-Chironomidae Chironomidae Brillia Brillia sp. Cardiocladius Cardiocladius sp. Cladotanytarsus Cladotanytarsus (Lenziella) sp Cladotanytarsus sp.
Hells Canyon Complex Page 65 Benthic Macroinvertebrates of Hells Canyon Idaho Power Company
Phylum Class Order Family Genus Taxa Codes
Downsteam Taxa Sampled: RM 189-219
Cricotopus Cricotopus (Cricotopus) sp. Cricotopus (Isocladius) sp. Cricotopus (Isocladius) Type I Cricotopus bicinctus gr. Phylum Class Order Family Genus Taxa Codes
Downsteam Taxa Sampled: RM 189-219
Cricotopus sp. Cricotopus tremulus gr. Cricotopus trifascia gr. Diamesa Diamesa sp. Dicrotendipes Dicrotendipes sp. Eukiefferiella Eukiefferiella claripennis gr. Eukiefferiella devonica gr. Eukiefferiella sp. Heleniella Heleniella sp. Limnophyes Limnophyes sp. Micropsectra Micropsectra sp. Nanocladius Nanocladius sp. Odontomesa Odontomesa sp. Orthocladius Orthocladius (Euortho.) luteipes Orthocladius (Euortho.) rivicola gr. Orthocladius (Euorthocladius) sp. Orthocladius (Orthocladius) sp. Orthocladius Complex Orthocladius obumbratus Orthocladius sp.
Page 66 Hells Canyon Complex Idaho Power Company Benthic Macroinvertebrates of Hells Canyon
Phylum Class Order Family Genus Taxa Codes
Downsteam Taxa Sampled: RM 189-219
Parametriocnemus Parametriocnemus sp.
Phaenopsectra Phaenopsectra sp. Polypedilum Polypedilum sp. Pseudosmittia Pseudosmittia sp. Rheocricotopus Rheocricotopus sp. Rheotanytarsus Rheotanytarsus exiguus gr. Rheotanytarsus sp. Smittia Smittia sp. Tanytarsus Tanytarsus sp.
Phylum Class Order Family Genus Taxa Codes
Downsteam Taxa Sampled: RM 189-219
Tvetenia Tvetenia sp. Undetermined Orthocladiinae Ephemeroptera Ameletidae Ameletus Ameletus sp. Baetidae Acentrella Acentrella sp. Baetis Baetis bicaudatus/tricaudatus Baetis sp. Baetis tricaudatus Diphetor Diphetor hageni Undetermined Baetidae Ephemerellidae Drunella Drunella coloradensis/flavilinea Ephemerella Ephemerella inermis/infrequens Undetermined Ephemerellidae Heptageniidae Cinygmula Cinygmula sp.
Hells Canyon Complex Page 67 Benthic Macroinvertebrates of Hells Canyon Idaho Power Company
Phylum Class Order Family Genus Taxa Codes
Downsteam Taxa Sampled: RM 189-219
Heptagenia Heptagenia sp. Stenonema Stenonema terminatum Undetermined Heptageniidae Leptophlebiidae Paraleptophlebia Paraleptophlebia sp. Tricorythidae Tricorythodes Tricorythodes sp. Lepidoptera Pyralidae Petrophila Petrophila sp. Odonata Cordulegasteridae Cordulegaster Cordulegaster sp. Plecoptera Chloroperlidae Sweltsa Sweltsa sp. Undetermined Chloroperlidae Leuctridae Undetermined Leuctridae Nemouridae Malenka Malenka sp. Podmosta Podmosta sp. Zapada Zapada cinctipes Taeniopterygidae Undetermined Taeniopterygidae Undetermined Undetermined Plecoptera Trichoptera Hydropsychidae Cheumatopsyche Cheumatopsyche sp.
Phylum Class Order Family Genus Taxa Codes
Downsteam Taxa Sampled: RM 189-219
Hydropsyche Hydropsyche sp. Undetermined Hydropsychidae Hydroptilidae Leucotrichia Leucotrichia sp. Lepidostomatidae Lepidostoma Lepidostoma sp. Leptoceridae Ceraclea Ceraclea sp. Limnephilidae Undetermined Limnephilidae
Page 68 Hells Canyon Complex Idaho Power Company Benthic Macroinvertebrates of Hells Canyon
Phylum Class Order Family Genus Taxa Codes
Downsteam Taxa Sampled: RM 189-219
Malacostraca Amphipoda Gammaridae Gammarus Gammarus sp. Talitridae Hyalella Hyalella sp. Isopoda Asellidae Caecidotea Caecidotea sp. Mollusca Bivalvia Veneroida Corbiculidae Corbicula Corbicula sp. Gastropoda Basommatophora Ancylidae Ferrissia Ferrissia sp. Physidae Physa Physa (Physella) sp. Planorbidae Vorticifex Vorticifex effusa Neotaenioglossa Hydrobiidae Potamopyrgus Potamopyrgus antipodarum Undetermined Hydrobiidae Nematomorpha Undetermined Undetermined Undetermined Undetermined Nematomorpha None None None None None NoInverts Platyhelminthes Turbellaria Undetermined Undetermined Undetermined Turbellaria
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