Assessment of Ecosystem Quality and its Impact on Resource Allocation in the Middle Snake River Sub- Basin / Evaluación de la calidad del Ecosistema y su impacto en la localización de recursos en la subcuenca del Río Snake Central

KEYWORDS: Middle Snake River; Milner Dam; King Hill; southern Idaho; risk assessment; water quality model; Geographic Information System (GIS)

ABSTRACT

The Middle Snake River sub- basin is currently ecologically stressed due to numerous point and non- point pollution sources, diversion of water for irrigation or hydropower, and a series of mainstem dams. Management strategies are crucial because of longterm claims on water, non- point source effects and new mainstem hydroelectric project proposals, as well as proposals for additional aquaculture facilities and other development on various tributaries. A multicompartment water quality model and an evaluation of historic biological resources are being used to characterize the ecological risks associated with proposed developments between Milner Dam and King Hill in southern Idaho. Central to the complex anthology of risks are the variability in flow, water quality and quantity, outflow, meteorologic inconsistencies, and model uncertainty compared with the variability in the environmental requirements for indicator organisms. Using Geographic Information System (GIS) techniques, ecological analyses are integrated into a system planning model which will provide a framework for examining management strategies for the sub- basin.

RESUMEN

La subcuenca del Río Snake central se encuentra actualmente estresada ecológicamente, debido a numerosas fuentes puntuales y no puntuales de contaminación, desviación de agua para irrigación o hidroeléctrica, y a una serie de presas prioritarias. Las estrategias de manejo son cruciales debido a los reclamos a largo plazo sobre el agua, los efectos de las fuentes no puntuales y las nuevas propuestas de proyectos hidroeléctricos prioritarios, así como las propuestas para facilidades adicionales para acuicultura y otros desarrollos en varios tributarios. Se están utilizando un modelo de calidad de agua multicompartamental y una evaluación histórica de los recursos biológicos para caracterizar los riesgos ecológicos asociados con los desarrollos propuestos entre la presa Milner y King Hill en el sur de Idaho. Central a la antología compleja de riesgos está la variabilidad en flujos, calidad y cantidad de agua, salidas, inconsistencias metereológicas, y modelo incierto comparado con los requerimientos ambientales para organismos indicadores. Utilizando la técnica del Sistema de Información Geográfica (SIG), los análisis ecológicos son integrados dentro de un modelo de sistema de planeación el cual proporcionará un marco para examinar las estrategias de manejo para la subcuenca.

CONTRIBUTED PAPER

Introduction

The Snake River extends 1,667 km from its origin in western Wyoming to its confluence with the Columbia River at Pasco, Washington. There is an elevation drop of 2,895 meters as the river descends its gradient. For the purposes of this study, the Middle Snake River extends from Milner Dam to King Hill (River Kilometers 1030.4 to 880.7). During its descent in this reach, the river's entrenchment exposes the Snake River Plain Aquifer as hundreds of small tributary springs arising from the north (right) bank (see Covington and Weaver, 1989; 1990a,b,c; 1991). The Snake River Plain Aquifer is an Environmental Protection Agency (EPA)- designated Sole Source Aquifer, providing domestic water for much of south- central Idaho. The tributaries arising from the Aquifer contribute up to 6,500 cfs, however, this has declined in recent years (Kjelstrom, 1992).

Ecosystem Degradation and Historical Perspectives

The Middle Snake River of the present is a transformed ecosystem when compared with its historic fauna and habitat. Since the advent of western exploration there has been an ongoing, synergistic and incremental change in the Middle Snake River ecosystem, including the extinction of enormous seasonal migratory runs of fall chinook and other salmon, white sturgeon and other migratory elements of the Columbia River fauna. Shoshone Falls (64.6 m. high; R.Km. 989.7) was the interior barrier for anadromous fish ascending the Snake River. The Snake River drainage above Shoshone Falls (Upper Snake River fauna) consists of fourteen native fish taxa. Below Shoshone Falls the historic Middle Snake River sub- basin fauna consisted of twenty- four native fish species (Smith [1978] reported twenty- three taxa; Oncorhynchus kisutch was subquently verifed from archeological sites, see Plew, 1981). This natural barrier has allowed at least one vicariant speciation; the Utah sucker (Catostomus ardens Jordan and Gilbert, 1880) from the Bonneville and Upper Snake River basins is a sister species to the largescale sucker (Catostomus macrocheilus Girard, 1857) of the Middle Snake River (see Smith, 1978, for further faunal analysis). Few species occur in both the Upper and Middle Snake River faunas; twenty- two species occur exclusively in one or the other of these faunal assemblages. Approximately eight of the twenty- four fish species native to the Middle Snake River sub- basin are no longer present. Several others are regarded as sensitive/special concern species by the Idaho Dept. of Fish and Game. The only vertebrate which is a federal Candidate species is the Shoshone sculpin, Cottus greenei (Gilbert and Culver) 1898, a narrowly restricted Middle Snake River endemic. By contrast, nearly two dozen non- native fish have been recorded (see Simpson and Wallace, 1978; Bowler, 1992; Bowler and Olmstead, 1990). Among the forty- three native aquatic mollusk taxa, there are four federally listed as Endangered, one as Threatened, and three as Candidate mollusks (U.S. Fish and Wildlife Service, December 14, 1992). All of these species historically sustained healthy populations in the lotic habitats within the gradient (Frest and Bowler, 1993).

When early explorers such as the Hunt Party (1811) and the Bonneville Expedition (1836) first reached this area they reported a river of extraordinary beauty and resources (Murphey, et al., 1992). At the site of Niagara/Crystal Springs, a designated National Natural Landmark (R.Km. 967.6), written accounts of early explorers found the entire river clear and abounding with wildlife resources. Massive runs of fall and summer chinook salmon (Oncorhynchus tschawytscha) and steelhead (Oncorhynchus mykiss) ascended the Middle Snake River as far upstream as the natural barrier of the 64.6 meter Shoshone Falls (R.Km. 989.7). Although not collected by the early researchers of the 1890s, coho salmon (Oncorhynchus kisutch) bones have been found in excavated Native American camps near Bliss (R. Km. 910.9) and at another site in the Middle Snake sub- basin (lew, 1981). Other Columbia River elements included anadromous and resident white sturgeon (Acipenser transmontanus) weighing up to 680 kilograms and the Pacific lamprey (Lampetra tridentata). The remnant white sturgeon population surviving in this reach appears to be a genotypic stock distinct from sturgeon in the Lower Columbia (G. Gall, pers. comm.), and exists today as isolated sub- populations in a few tailwater reaches.

Although there were year- round resident groups, Native American Shoshoni and Bannock tribes congregated at Upper (R. Km. 935) and Lower Salmon Falls (R. Km. 922.2) to utilize the migratory anadromous fishery. The subsistence provided by the anadromous fishery was the mainstay of their fall and winter existence. Commercial fishery operations by non- Indian pioneers were common along the Middle Snake River from Weiser (R. Km. 565.4) to Glenns Ferry (R.Km. 870.4) to Hagerman (R.Km. 924.1) (Evermann, 1896; Gilbert and Evermann, 1894). Salmon carcasses would line the banks, and were scavanged by eagles, coyotes and other predators. Large numbers of Pacific lamprey were present in the river as far upstream as Shoshone Falls, and their ammocoetes (larvae) served as a rich forage base for sturgeon and other bottom feeding fishes. Prior to their local extirpation in the late 1940s with the closing of Bliss Dam, adult lamprey were highly prized as sturgeon bait.

The U.S. Fish Commission research expeditions to Columbia River headwater sites in the early 1890s were stimulated by severe declines in commercial fishery harvests, so that the early reports of Evermann and his colleagues for the Middle Snake River fishery reflected a severely depleted fall chinook migration (the skewed sex ratio and small size classes of fish reported in Evermann [1896] are also suggestive of a declining fishery). The Fish Commission expedition found the Hagerman Valley the best site in Idaho for establishing hatcheries to supplement the diminishing fishery: "The salmon visit this part of the river in sufficient numbers to furnish roe for hatching, and this is probably the most available point where suitable water and an abundance of fish can be found for such a station in Idaho" (Gilbert and Evermann, 1896). Evermann (1896) observed that, "A little blasting at these falls (Lower Salmon) would make it very much easier for the salmon to ascend...and would result in a considerable increase in salmon supply in the Snake River." Damage to salmon spawning areas in the Hagerman Valley from mining was also evident in the 1890s, as reported by Evermann (1896): "The Indians that come here say the salmon prefer the sandy beds, and that the coarse gravel which the miners have run into the river has caused the salmon to seek other spawning- beds."

Paste Watson et al. Table 1 here - sideways

The historic anadromous fishery has been absent from the Middle Snake River for nearly half a century (see Table 1). The anadromous salmonids were first severely impacted around 1910 by the construction of Swan Falls Dam (R.Km. 736.9), which lacked a fish ladder. Although a poorly sited ladder was installed a decade or so later, the dam remained a major barrier to migrating salmon and steelhead. A few fall chinook salmon were subsequently reported from the Bruneau River (R.Km.796.5). However, steelhead successfully re- invaded the sub- basin to Lower Salmon Falls. When Lower Salmon Falls Dam was raised in 1948 a fishway was installed; Upper Salmon Dam also had a fish ladder, albeit badly located (see Irving and Cuplin, 1956). Fish and Game surveys of fall chinook salmon spawning redds below Swan Falls Dam in the late 1940s reported extensive siltation of spawning habitat from dam construction in the Hagerman Valley, over 175 river kilometers upstream (see Zimmer, 1950 with supplements in 1951 and 1953 for survey data; Idaho Department of Fish and Game, 1953). The final mainstem hydroelectric developments which terminated the anadromous fishery in the Middle Snake River were the sequential closures of Bliss Dam (R.Km. 902.8; 1949; no fish passage provided), C.J. Strike Dam (R.Km. 729.1; 1952; see Irving and Cuplin, 1956; no fish passage), and ultimately the trilogy of Idaho Power Company projects in Hells Canyon (Brownlee Dam, 1958; Oxbow Dam, 1962; Hells Canyon Dam, 1967).

Modern Ecological Problems: Mollusks and Macrophytes as Bioindicators

As Frest and Bowler (1993) report elsewhere in this volume, the native mollusk fauna of the Middle Snake River is a rich assemblage of forty- three species, but, like the faunal transformation already apparent in the native fishes, there is a habitat and water quality determined change occurring within the molluscan fauna in this river reach. Toward the end of the last decade, there has been a remarkable expansion in enormous populations of the New Zealand mud snail, Potamopyrgus antipodarum (Bowler, 1990). First observed in the river in 1987 by D.W. Taylor, within three years this tiny (4- 5 mm) gastropod became the dominant invertebrate in this section of the Snake River. As Haynes, et al. (1985) noted, its small size makes it well suited for passive dispersal by birds and fish. This species is parthenogenetic, and as a live bearer is able to tolerate pollution to a much greater degree than many native taxa. Potamopyrgus is reproductively much more successful than the native molluscs with which it co- exists. It is able to rapidly retreat beneath rocks during diurnal water level fluctuations, and appears more resistant to the desiccation caused by raising and lowering river levels to match peak hydroelectric loads than the native snails found in similar shallow riffle habitats. Frest and Johannes (1991) report densities of up to 640,000 individuals per square meter in the river near Thousand Springs. While the large numbers of Potamopyrgus would make it superficially seem a potentially significant forage species for organisms higher on the river food chain, it has been shown to be capable of surviving passage through alimentary canals of both trout and yellow perch (Haynes, et al., 1985). This species is overwhelmingly dominant in shallow water habitats and on macrophytes at most sites.

The rapid population building of Potamopyrgus was paralleled by a corresponding precipitous decline in populations of indigenous mollusk species which are less pollution- tolerant. Four Middle Snake River gastropods were recently listed as federal Endangered Species (Physa natricina, Pyrgulopsis idahoensis, Lanx n. sp., and Valvata utahensis), another was listed as Threatened (the Bliss Rapids snail, an unnamed hydrobiid), and there are three additional taxa which are federal Candidate species (Anodonta californiensis, Fisherola nuttalli, and Fluminicola columbiana). As Frest and Bowler (1993) report in this volume, there are many other lotic, coldwater preferring species which are declining in the Middle Snake River, while a large group of species which are characteristic of warmer, lentic waters are increasing. The large freshwater clam, Margaritifera falcata, one of the most abundant clams in Native American archaeological sites, is now virtually eliminated from the Middle Snake River (Bowler, 1990). This may have been a result of the extinction of salmon runs in the area, as M. falcata larvae require salmonids as preferred hosts during their brief attachment stage. This species has been replaced by the smaller pelecypod Gonidea angulata.

Loss of riparian habitat and a seasonal burgeoning of aquatic macrophytes, especially Potamogeton spp., has also occurred as a result of nutrient loading and other agricultural nonpoint source pollution. Extensive blooms of planktonic and periphytic algae appear during the spring and summer, and anoxic bottom conditions occur on the thick sediment blanket as early as April. The oxygen- poor bottom conditions exclude most mollusks, and the fishery is characterized by lentic, eutrophic tolerant taxa, particularly catostomids, squawfish, other native cyprinids, and the non- native carp. Recreational use is seasonally restricted by these conditions, particularly boating, water skiing, swimming, and fishing. Jet boats are more utilitarian than those with propellers due to macrophyte growth during the summer in impoundments or lentic sites in the reach.

Ecological Stresses on the Middle Snake River

The Middle Snake River's ecological stessors, which in concert have led to the decline of water quality and the aquatic ecosystem, are numerous and synergistic. Diversion of the Snake River for irrigation purposes at Milner Dam is an historic practice which dewaters the river downgradient to Shoshone Falls during the agricultural season, although there has always been a limited leakage through the dam, and recent Federal Energy Regulatory Commission rules now require a minimum flow of 300 cfs below Milner. High- lift irrigation pumping from the Snake River occurs in Lower Salmon impoundment to irrigate the Bell Rapids agricultural project on the left bank, and a high- lift pump station in the Bliss impoundment provides irrigation water for other agricultural areas on the left bank of the river between Bliss and King Hill. Kjelstrom (1992) presented data indicating that the annual average ground- water discharge, primarily spring flows from the Snake River Plain Aquifer, have declined significantly in the past decade, but especially during the past five years. This pattern appears strongly evident in Box Canyon and Blue Lakes, two of the largest aquifer tributaries for which there are longterm accurate data, as well as in monitoring wells (Kjelstrom, 1992). Groundwater pumping and the current drought may contribute to this decline.

Paste Table 2 & Figure 1 for Watson et al. here (full page)

Primary point and non- point pollution sources include effluent from over 140 fish hatcheries, between 400 and 500 dairies and feedlots, irrigated agriculture runoff, municipal sewage discharge, and a series of mainstem dams (see Table 2). Nearly every tributary from the Snake River Plain Aquifer arising on the right or north bank of the river has been extensively developed, particularly with fish rearing facilities. Between June 1, 1990 and July 25, 1991, Brockway and Robison (1992) examined a transect through the reach sampling thirteen mainstem sites, summarizing STORET data for others, and surveying 19 irrigation return flows, 13 tributaries, and 10 aquaculture effluent streams. According to that study, suspended solids at times exceeded 3,000 mg/l in irrigation return flows, with an estimated 350 tons/day transported by the river at King Hill. The total inflow from 18 irrigation return flows was 21,000 tons, from the ten fish farms sampled an estimated 6,000 tons, and from 9 tributaries 53,000 tons (Brockway and Robison, 1992). Total phosphorus increased from 100 tons at Blue Lakes to over 600 tons at King Hill, with the lowest contributions being in July or mid- summer and the highest appearing in the spring. An estimated 37 tons were contributed by the irrigation return flows sampled, 112 tons from the ten fish hatcheries surveyed, and 219 tons annually from measured tributaries. (It should be noted that return flows from irrigated agriculture have been relatively low in recent years due to drought conditions in southern Idaho; the temporal pattern of pollution input could be altered during wet years, so that periods of intense phosphorus contribution could continue much longer in above median water years. Similarly, "flushing flows" or years with extended runoff could re- suspend nutrient rich sediments which would pass through the system, settling in impoundments and lentic sites down gradient, and, perhaps stimulating algal growth in the process.) In the Brockway and Robison (1992) study, total phosphorus was greater than 0.1 mg/l at all sample sites at some point during the study term; at Murtaugh total P reached 0.33 mg/l, and the mean of all sites was 0.08 mg/l which represented 2 tons/day of total P. Phosphorus values of greater than 0.025 mg/l are considered to be levels promoting growth of algae and macrophytes (see discussion in EPA [1991] and TMDL literature review in Cusimano [1992]), and although there is variation in the current chemistry of the area's springwater, values as low as 0.01 mg/l are reported in STORET and Brockway and Robison (1992).

Nitrate plus nitrite measurements similarly indicated that the 0.3 mg/l level considered as an indicator level of pollution was exceeded at all 13 river sites in all but two samples. The ten fish hatcheries sampled contributed 1,600 tons/year, while 190 tons were generated by irrigation return flows and 3,600 from tributaries (which also reflect agricultural runoff). The EPA and the Idaho Department of Health and Welfare, Division of Environmental Quality (IDHW DEQ) have sponsored several additional studies to further examine the impacts these point source and nonpoint source pollution contributors have upon the Middle Snake River. A literature review and comprehensive bibliographic database for biotic resources in the Middle Snake River ecosystem is presented in Dey and Minshall (1992).

Ecosystem Analysis and Risk Modeling in Resource Allocation

Restoration of the aquatic resources in the Middle Snake River requires environmental planning with an ecosystem perspective. This implies gaining a better understanding of and articulating the basic interactions of this complex ecosystem. It also necessitates developing methods for assessing the impacts of resource allocation upon ecosystem quality. Present understanding of the Middle Snake River is based upon limited hydrologic and water chemistry data. This is because the historical, utilitarian view of the Middle Snake River ecosystem was as an anthropocentric resource whose primary values were irrigation, the generation of hydroelectric power, and for the production of fish in commercial aquaculture hatcheries. The intrinsic values of this unique river segment with its remarkable deciduous riparian forests, endemic mollusks, the historic anadromous fishery, and the surviving vertebrate endemics such as the Shoshone sculpin are only beginning to be understood. To enhance the development of this perspective, as mandated by the Clean Water Act (see EPA [1991] for a discussion of implementing the Clean Water Act sections), the Region 10 Environmental Protection Agency in cooperation with the IDHW DEQ is designing a methodology for characterizing the risk of further altering the ecosystem for known and proposed levels of development.

Goals

The goals of the Middle Snake River restoration project have elements which are short and longterm. The development of a methodology using GIS and other techniques to address the existing and potential, or at least predictable, problems is an immediate challenge. EPA Region 10 has approached this by providing its technical support for: 1) review of permits for licensing existing and proposed hydroelectric projects; 2) evaluation of management plans for identifying and controlling nonpoint source pollution; 3) establishment of Total Maximum Daily Loads (TMDL's) for water quality- limited segments of the river; and 4) assisting in the writing of permits under the National Pollution Discharge Elimination System (NPDES). The longterm goals are to develop an ecosystem perspective for environmental planning which can be applied to tributaries in other river basins or sub- basins throughout the region.

Risk Modeling Assumptions

As in any predictive or descriptive model, the characterization of ecological risk through modeling is based upon assumptions which are the direct products of data from historic and ongoing research. These assumptions include:

1. Major features of the Snake River ecosystem can be described in terms of compartments between which there can be flows of energy, material and information.

2. The flows of energy, material and information can be described mathematically within given bounds of uncertainty.

3. There is sufficient information to characterize the variability of forcing functions associated with meteorology, hydrology and water chemistry.

4. There is sufficient information to characterize the variability of environmental forcing functions associated with important types of human development on the Snake River.

5. Assessment endpoints for biological systems included in the risk analysis are known within given bounds of uncertainty. Where endpoints are not known, surrogates, such as water quality standards can be applied.

6. The principal components of risk arise from uncertainty or variability in driving forces and from uncertainty in the models used to describe the state of the ecosystems.

Objectives and Ecosystem Modeling Strategy: Short- term Objectives

The objectives of the short- term goals are associated with and largely driven by specific requirements of state and federal environmental legislation and the development of comprehensive land- use plans at the county level. They are also determined by the state of our knowledge of the ecosystem and our ability to develop simulation models for the flow of energy, material and information between ecosystem compartments. At present it is possible to accurately apply the methodology to a limited part of this complex ecosystem.

To achieve these objectives within the framework of the risk analysis, a "source- based" strategy is being employed. While this strategy has elements of the traditional approach to the allocation of waste loadings, it also contains elements of risk analysis. The focus of the model is upon water quality including as parameters temperature, dissolved oxygen, nutrients such as nitrate/nitrite N and total P, coliform bacteria, and ammonia toxicity. The State of Idaho's water quality standards are assessment endpoints in this method. The assessment methodology is based upon a mass balance water quality model. Elements of risk are derived from uncertainty and variability in driving forces, and from uncertainty in the mass balance model. The water quality model of Yearsley (1991) utilizes material and energy flows as shown in Figure 2. This model employs standard kinetics theory to simulate temperature, dissolved oxygen, nitrogen, phosphorus, and primary productivity for time scales of hours to decades, vertical length scales of 1- 10's of meters and horizontal scales of 100's of meters to 100's of kilometers.

Paste Figure 2 & Figure 3 of Watson et al. here - full page

Through this method, measures of the risk of exceeding the State of Idaho's water quality standards can be estimated before and after source control or mitigation. This concept is illustrated in Figure 3 where the probability density of total phosphorus is shown schematically before and after TMDLs have been implemented for nutrient generating sources. The probability densities are estimated empirically by Monte Carlo simulation using variability and uncertainty in driving forces as determined from available data. Model uncertainty will be determined by comparing simulation results with measurements obtained in comprehensive field experiments such as those reported by Brockway and Robison (1992).

Long Term Goals and Objectives

Longterm goals include an analysis of the communities within the mainstem river ecosystem encompassing the benthic, planktonic, and riparian/wetland habitats. Sampling of these habitats was conducted in two separate studies during the spring/summer and fall/winter of 1992. Additional field measurements will be taken during spring/summer of 1993. The results of this research are presently being integrated into the model to refine predictive accuracy. This is particularly critical now that there are four federally listed Endangered and one Threatened species of mollusks in the Middle Snake River, as well as three additional Candidate mollusk species (U.S. Fish and Wildlife Service, 1992).

The objectives associated with longterm goals include increasing our knowledge of the Snake River ecosystem with additional field studies and experiments, and allowing expansion of the scope of simulation methods to encompass more complex compartments such as benthic plants and animals, and higher trophic levels in the river. More complex models will inevitably lead to more comprehensive risk assessment methods.

Comprehensive Management Plan for the Middle Snake River

In addition to the studies of the ecosystem, another component of the long term goals is a comprehensive management plan which involves close coordination of government, public and private interests. To meet this goal, several working groups have been formed.

The Mid- Snake River Planning Group consists of representatives of Twin Falls, Gooding, Lincoln and Jerome Counties, along with federal, state and local government entities. Its purpose is to develop a management plan to prioritize problems in the basin and to provide direction for solving them.

The IDHW, DEQ is in the process of developing a nutrient management plan which includes short- term monitoring and modeling studies in the Snake and several small tributaries, a compilation of existing data, identification of land use data, algal bioassays, identification of regulatory and voluntary solutions to achieve target nutrient level/water quality goals and an assurance of public participation in the process. Executive and Technical Advisory Committees including representatives of private industry, conservation, and other groups allow additional participation.

The Bureau of Land Management has recently undertaken a Wild and Scenic River study of three reaches within the Middle Snake River, which adds another evaluative contributor to the resources of the reach. The Lower Salmon Falls Dam tailwaters were identified as a promising candidate for Wild and Scenic River recognition in the Nationwide River Inventory conducted by the Heritage Conservation Recreation Service in the early 1980s (the Wild and Scenic Rivers Act is now implemented by the National Park Service). This section of the reach was also found to qualify for National Natural Landmark recognition as were Box Canyon (R. Km. 946.6) and Malad Gorge (Snake River Km. 919.6 at the confluence to Big Wood River [Malad} Km. 4.7), though none were formally designated as Landmarks (Bowler, 1981a,b,c).

Summary and Conclusions

Because of human activities during the past century the Middle Snake River and its immediate tributaries exhibit water quality and natural resource problems. These include the extinction of an extraordinary anadromous fishery, the diminishment of mollusk populations and species to a level of endangerment, the reduction of habitat and populations of the endemic Shoshone sculpin, and the diminishment of several other native fishes now accorded sensitive species status. The rapid growth of southern Idaho, as well as the increasing requirements for energy and irrigation resources, places an added urgency upon resolving long- standing problems. It is crucial that all parties very clearly understand the severity of the present ecological stress and the extinctions which have already occurred in this reach.

Acknowledgements

We thank two anonymous reviewers from the Society of Environmental Toxicology and Chemistry and L. W. Barnthouse of Oak Ridge National Laboratory for helpful comments on an early draft of this paper.

Literature Cited

Bowler, P.A. 1981a. Natural History Studies and an Evaluation of Eligibility of Box Canyon for National Natural Landmark Designation, and Natural Landmark Brief. Heritage Conservation and Recreation Service (National Park Service) Open- File Report.

Bowler, P.A. 1981b. Natural History Studies and an Evalution for Eligibility of the A.J. Wiley Reach of the Snake River for National Natural Landmark Designation, and Natural Landmark Brief. Heritage Conseravtion and Recreation Service (National Park Service) Open- File Report.

Bowler, P.A. 1981c. Natural History Studies and an Evaluation for Eligibility of Malad Canyon for National Natural Landmark Designation, and Natural Landmark Brief. Heritage Conservation and Recration Service (National Park Service) Open- File Report.

Bowler, P.A. 1990 (1991). Rapid Spread of the freshwater hydrobiid snail Potamopyrgus antipodarum (Gray) in the Middle Snake River, Southern Idaho. Proceedings of the Desert Fishes Council 21: 173- 182.

Bowler, P.A. 1992. The Non- Native Snail Fauna of the Middle Snake River, Southern Idaho. Proceedings of the Desert Fishes Council 23: 28- 44.

Bowler, P.A. and P. Olmstead. 1990 (1991). The Current Status of the Bruneau Hot Springs Snail, an Undescribed Monotypic Genus of Freshwater Hydrobiid Snail, and Its Declining Habitat. Proceedings of the Desert Fishes Council 21: 195- 211.

Brockway, C.E. and C.W. Robison. 1992. Middle Snake River Water Quality Study Phase 1. Final Report submitted to the Idaho Dept. of Health and Welfare, Department of Environmental Quality.

Covington, H.R. and J.N. Weaver. 1989. Geologic Map and Profiles of the North Wall of the Snake River Canyon, Bliss, Hagerman, and Tuttle Quadrangles, Idaho. U.S. Geological Survey, Miscellaneous Investigation Series, Map I- 1947- A.

Covington, H.R. and J.N. Weaver. 1990a. Geologic Map and Profiles of the North Wall of the Snake River Canyon, Pasadena Valley and Ticeska Quadrangles, Idaho. U.S. Geological Survey, Miscellaneous Investigation Series, Map I- 1947- B.

Covington, H.R. and J.N. Weaver. 1990b. Geologic Map and Profiles of the North Wall of the Snake River Canyon, Jerome, Filer, Twin Falls, and Kimberly Quadrangles, Idaho. U.S. Geological Survey, Miscellaneous Investigation Series, Map I- 1947- D.

Covington, H.R. and J.N. Weaver. 1990c. Geologic Map and Profiles of the North Wall of the Snake River Canyon, Eden, Murtaugh, Milner Butte, and Milner Quadrangles, Idaho. U.S. Geological Survey, Miscellaneous Investigation Series, Map I- 1947- E.

Covington, H.R. and J.N. Weaver. 1991. Geologic Maps and Profiles of the North Wall of the Snake River Canyon, Thousand Springs and Niagara Springs Quadrangles, Idaho. U.S. Geological Survey, Miscellaneous Investigation Series, Map I- 1947- C.

Cusimano, R.F. 1992. Technical Guidance for Assessing the Quality of Aquatic Environments. A Handbook Prepared for the Water Quality Financial Assistance Program. Washington State Department of Ecology, Olympia, Washington.

Dey, P.D. and G. W. Minshall. 1992. Middle Snake River Biotic Resources: A Summary of Literature in the Snake River Water Quality Assessment Bibliographic Database. Final Report. Volume I. Prepared for the U.S. Enivronmental Protection Agency Region 10, Seattle, Washington.

Environmental Protection Agency. April, 1991. Guidance for Water Quality- based Decisions: The TMDL Process. Assessment and Watershed Protection Division, U.S. Environmental Protection Agency, Washington, D.C. EPA 440/4- 91- 00.

Evermann, B.W. 1896. A Preliminary Report upon Salmon Investigations in Idaho in 1894. Bulletin of the United States Fish Commission 15 (for 1895): 253- 284.

Frest, T.J. and P.A. Bowler. 1993. A Preliminary Checklist of the Molluscs of the Middle Snake River. Proceedings of the Desert Fishes Council 24: in press.

Frest, T.J. and E. Johannes. 1991. Mollusk fauna in the vicinity of three proposed hydroelectrc projects on the middle Snake River, Central Idaho. Final Report, Prepared for Don Chapman Associates, Inc., Boise, Idaho. Deixis Consultants, 6842 24th Ave N.E., Seattle, WA 98115.

Gilbert, C.H. and Evermann. 1894. A report upon investigations in the Columbia River Basin, with descriptions of four new species of fishes. Bull. U.S. Fish Commiss. 14: 169- 204.

Haynes, A., B.J.R. Taylor, and M.E. Varley. 1985. The influence of the mobility of Potamopyrgus jenkinsi (Smith, E.E.) (Prosobranchia: Hydrobiidae) on its spread. Arch. Hyrdrobiol. 103: 497- 508.

Idaho Department of Fish and Game. 1953. The Size and Timing of Runs of Anadromous Species of Fish in the Idaho Tributaries of the Columbia River. Prepared for the U.S. Army, Corps of Engineers by the Idaho Fish and Game Department.

Irving, R.B. and P. Cuplin. 1956. The effect of hydroelectric development on the fishery resources of the Snake River. Idaho Department of Fish and Game. Boise, Idaho.

Kjelstrom, L.C. 1992. Assessment of Spring Discharge to the Snake River, Milner Dam to King Hill, Idaho. Water Fact Sheet. U.S. Geological Survey Open- File Report 92- 147.

Murphey, K., M.J. Crutchfield, and P.A. Bowler. 1992. An Ethnographic and Natural History of the Hagerman Valley. Hagerman Valley Historical Society, Hagerman, Idaho.

Plew, M.G. 1981. Archeological test excavation at four prehistoric sites in western Snake River Canyon near Bliss, Idaho. Idaho Archeological Consultants. Project Report No. 4. Boise, Idaho.

Simpson, J. and R. Wallace. 1978. Fishes of Idaho. The University Press of Idaho, Moscow, Idaho.

Smith, G.R. 1978. Biogeography of Intermountain Fishes. Great Basin Memoirs No. 2: 17- 42.

U.S. Fish and Wildlife Service. December 14, 1992. Endangered and Threatened Wildlife and Plants; Determination of Endangered or Threatened Status for Five Aquatic Snails in South Central Idaho. Final Rule. Federal Register 57(240): 59244- 59257.

Williams, R.M., J.E. Carter, D.K. Shiozawa, and R.F. Leary. 1991. Taxonomic and Genetic Analysis of Five Rainbow Trout Populations from Southern Idaho. Boise State University Evolutionary Genetics Lab Report 91- 2.

Yearsley, J.R. 1991. A dynamic river basin water quality model. EPA Publ. #910/9- 91- 019. EPA Region 10, Seattle, Washington. 22 pp.

Zimmer, P.D. 1950. A Three Year Study of Fall Chinook Salmon Spawning Areas in the Snake River Above Hells Canyon Dam Site. Supplements in 1951 and 1953. U.S. Fish and Wildlife Service Report.

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