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Fact Sheet 198-96

National Water Quality Assessment Program

Activities of the National Water-Quality Assessment Program in the Upper Snake River Basin, Idaho and western Wyoming, 1991-2001

By Walton H. Low

Background

In 1991, the U.S. Geological Survey (USGS) began a full-scale National Water-Quality Assessment (NAWQA) Program. The long-term goals of the NAWQA Program are to describe the status and trends in the water quality of a large part of the Nation's rivers and aquifers and to improve understanding of the primary natural and human factors that affect water-quality conditions. In meeting these goals, the program will produce water-quality, ecological, and geographic information that will be useful to policy makers and managers at the national, State, and local levels.

A major component of the program is study-unit investigations, upon which national-level assessment activities are based. The program's 60 study-unit investigations are associated with principal river basins and aquifer systems throughout the Nation. Study units encompass areas from 1,200 to more than 65,000 mi2 (square miles) and incorporate about 60 to 70 percent of the Nation's water use and population served by public water supply. In 1991, the upper Snake River Basin was among the first 20 NAWQA study units selected for implementation. From 1991 to 1995, a high-intensity data-collection phase of the upper Snake River Basin study unit (fig. 1) was implemented and completed. Components of this phase are described in a report by Gilliom and others (1995).

In 1997, a low-intensity phase of data collection began, and work continued on data analysis, report writing, and data documentation and archiving activities that began in 1996. Principal data-collection activities during the low-intensity phase will include monitoring of surface-water and ground-water quality, assessment of aquatic biological conditions, and continued compilation of environmental setting information.

Completed Surface Water Activities, 1991-1995

About 300 monthly and extreme-flow samples were collected at 12 sites (table 1) during the high-intensity phase from April 1993 to June 1995. Also, weekly pesticide samples were collected at Teton River and Rock Creek sites from April 1993 to August 1993. Monthly samples were collected from the Snake River at Flagg Ranch, near Blackfoot, near Buhl, and at King Hill and Rock Creek through September 1995. Sites were selected to represent reference sites with relatively undisturbed land, indicator sites with a single predominant land use, or integrator sites with multiple land uses table 1).

Table 1. High-intensity phase surface-water quality and ecological survey sites
Site No. Site Name Intervening Basin Area (sq. miles) Site Type Land Use
13010065 Snake River at Flagg Ranch, WY 511 Reference Forested (reference)
13027500 Salt River near Etna, WY 829 Indicator Agriculture
13055000 Teton River near St. Anthony, ID 890 Indicator Agriculture
13056500 Henrys Fork near Rexburg, ID 2,920 Indicator Agriculture
13069500 Snake River near Blackfoot, ID 11,310 Integrator Mixed
13073000 Portneuf River at Topaz, ID 570 Indicator Agriculture
13081500 Snake River near Minidoka, ID 15,700 Integrator Mixed
13092747 Rock Creek at Twin Falls, ID 277 Indicator Agriculture
13094000 Snake River near Buhl, ID 17,139 Indicator Mixed
13120500 Big Lost River near Chilly, ID 450 Indicator Rangeland
13152500 Malad River near Gooding, ID 2,990 Indicator Agriculture
13154500 Snake River at King Hill, ID 6,650 Integrator Mixed

Sample collection followed established NAWQA protocols designed to minimize sample contamination. Runoff conditions during the sampling period included extreme drought and average and above-average snowmelt runoff. Quality assurance samples were collected and analyzed at all sites.

Three synoptic surveys for nutrients, suspended sediment, and pesticides were conducted in 1994 and 1995 to provide greater spatial resolution for sources of contaminants in water discharging to the Snake River. A high-flux/high-use synoptic survey was conducted at 35 sites on the Snake River and major tributaries in 1994. A second high-flux/high-use synoptic survey was conducted at 10 sites on Rock Creek, agricultural tunnel drains, and agricultural drains in 1994. A third synoptic survey was conducted at selected sites on the State-declared water-quality-limited reach of the Snake River between Milner Dam and King Hill during the late irrigation season in 1995. High-flux/high-use refers to the period of the irrigation season during which land application of chemicals, contaminant discharge, and water use are intensive.

Special studies of the water quality of 10 selected springs between Twin Falls and Hagerman were completed at the beginning of the irrigation season in April 1994 and after the irriga-tion season in October 1994. Spring discharge during this sampling period accounted for about 65 percent of the discharge of the Snake River at the King Hill site. These studies provide information on ambient water-quality conditions of relatively undisturbed springs and information on the effect of the water quality of springs on the Snake River.

Planned Surface-water Activities, 1997-2001

Two low-intensity phase surface-water quality sites, one on the Snake River and one on Rock Creek table 2), were selected from sites sampled during 1993 to 1995, in accordance with established NAWQA Program guidelines and in consideration of hydrology, land use, water use, and local water-quality management issues. Water-quality management issues focus on the main-stem Snake River because water-quality effects are the result of land and water use near the Snake River and near the mouths of its major tributaries and of discharge from the Snake River Plain aquifer system. Also, the hydrology of and runoff in the Snake River Basin are controlled by numerous reservoirs and a network of canals for irrigation. As a result, sampling frequency is based on flow-controlled discharge. To complement the two low-intensity phase sites, water samples from eight additional sites will be analyzed for major ion, nutrient, and suspended sediment concentrations. These samples will be collected as part of the Idaho Surface-Water Quality Monitoring Network, a cooperative USGS and Idaho Division of Environmental Quality (formerly Idaho Department of Health and Welfare, Division of Environmental Quality) program.

Table 2. Low-intensity phase surface-water quality and ecological survey sites
Site No. Site Name Intervening basin area
(sq. mi)
Site Type Annual Sampling Schedulte for Major Ions, Nutrients, and Sediment Annual Sampling Schedule for Pesticides
13092747 Rock Creek at Twin Falls, ID 241 Indicator Bimonthly; Monthly Apr-Sept.
13154500 Snake River at King Hill, ID 6,650 Integrator Monthly Monthly

The Rock Creek at Twin Falls site (tables 1 and 2) is affected by upstream land use, water use, and ground-water inflow. The intervening 241-mi2 basin area represents parts of the Snake River Basin and Northern Basin and Range ecoregions. Water from Milner Lake on the Snake River is diverted for irrigation of adjacent croplands. Irrigated agriculture is the predominant land use on about 58 mi2, or 24 percent of the intervening basin area. Principal crops are potatoes, grains, corn, and sugar beets. Discharge at the Rock Creek site has been measured continuously since 1993. The lowest and highest annual mean discharges during 1993 ­ 95 were 99.3 and 122 ft3/s, respectively. The annual mean discharge during the same period was 113 ft3/s. Major water-quality issues and management activities are focused on areas upstream and downstream from the Rock Creek site.

The Snake River at King Hill site (tables 1 and 2) integrates basinwide land-use, water-use, and ground-water inflow effects. The intervening 6,650-mi2 basin area between the Buhl and King Hill sites (table 1) is within the Snake River Basin, Northern Rockies, and Northern Basin and Range ecoregions. Land use is predominantly irrigated agriculture on about 996 mi2, or 15 percent of the intervening basin area. Principal crops are potatoes, grains, corn, and sugar beets. Dairy, aquacultural, and food-processing operations are other major land and water uses in the intervening basin area. Discharge at King Hill has been measured continuously since 1909. The lowest and highest annual mean discharges during 1909-95 were 7,004 and 18,070 ft3/s, respectively. The annual mean discharge during the same period was 10,730 ft3/s. Water-quality trends of ground-water discharge from the 10,500-mi2 Snake River Plain regional aquifer system also are monitored at this site.

Beginning in May 1997, 12 samples per year at each low-intensity phase site will be collected and analyzed for major ions, nutrients, and suspended sediment table 2). Pesticide samples also will be collected twice per month from April to September at the Rock Creek site and once per month at the Snake River site table 2). Data will be compiled, reviewed, and published in the USGS annual Water-Resources Data report for Idaho.

Completed Ecological Activities, 1992-1995

Ecological surveys, including ecological synoptic surveys and intensive ecological assessments, were conducted at 30 river and spring sites in the upper Snake River Basin during 1993-95. These surveys were completed during summer and fall low-flow conditions at the 12 water-quality sites (table 1 and fig. 2), 12 least-disturbed reference river sites (fig. 2), and 6 least-disturbed spring sites (fig. 2). Least-disturbed reference sites are sites that showed little evidence of human disturbance. Fish, macroinvertebrate, and algae samples were collected for taxonomic identification and enumeration, and associated habitats were assessed. Voucher samples of aquatic species were preserved and archived. Continuous water temperature also was recorded at the 12 water-quality and 6 spring sites.

The ecological synoptic survey of 6 least-disturbed springs between Twin Falls and Hagerman was completed during April to June 1994 (at the beginning of the irrigation season) in cooperation with the U.S. Fish and Wildlife Service. The survey of springs will provide information with which to describe and characterize the aquatic biology and associated habitat of some of the remaining least-disturbed springs in this area. Some of these springs currently support federally listed endangered snail species and are part of the focus of major State water-quality issues.

Intensive ecological assessments of year-to-year variability in biological communities and contaminants in bed sediment and biological tissue were completed at 6 of the 12 water-quality sites during 1993-95. These sites were sampled for 3 consecutive years during the same 1993-95 period. An intensive habitat survey also was completed in 1995 to characterize stream channel morphology, which included longitudinal profiles, cross-sectional surveys, and substrate description. At two of these sites, ecological assessments were completed at multiple reaches (three per site) to estimate expected variability in fish, macroinvertebrate, and algae samples collected within a river segment.

An occurrence and distribution survey of contaminants in bed sediment and biological tissue (whole-body fish and macroinvertebrates) at 27 river sites was completed during 1992-93. These samples were analyzed for trace elements and organochlorine compounds. Sportfish were collected at one river site to determine contaminant concentrations in edible portions of the fish. The survey was designed to identify significant contaminants and to determine their areal distribution within the study unit.

Planned Ecological Activities, 1997-2001

Selected aquatic communities and habitat will be assessed annually at the two low-intensity phase sites table 2). Fish, macroinvertebrate, and algae taxonomy and enumeration and selected habitat assessments will be conducted annually. Bed sediment and tissue samples for contaminant analyses will be collected at each site triennially beginning in 1997.

The low-intensity phase aquatic biological sampling sites were selected in accordance with established guidelines similar to the surface-water quality site guidelines. To complement the two low-intensity phase sites, selected biological data will be collected at six high-intensity phase sites and two high-intensity phase synoptic sites as part of the Idaho Surface-Water Quality Monitoring Network. Data will be compiled, reviewed, and published in the USGS annual Water-Resources Data report for Idaho.

Completed Groundwater Activites, 1991-1995

Land-use studies were completed for areas associated with the Snake River Plain aquifer and a local alluvial aquifer in southern Minidoka and northern Cassia Counties in 1993 (figs. 1 and 3), in the Snake River Plain aquifer in western Jerome and southern Gooding Counties in 1994, and in eastern Jerome County in 1995 (figs. 1 and 4). These studies assessed concentrations and distributions of constituents in recently recharged ground water. Water samples from 105 wells were analyzed for major ions, nutrients, semivolatile organic compounds, and pesticides. Prescribed quality assurance samples composed 23 percent of the total ground-water quality analytical costs. Samples from selected wells were analyzed for tritium, chlorofluorocarbons, deuterium, oxygen-18, nitrogen-15, and nitrate-nitrogen-15/oxygen-18. Samples from nine wells upgradient from Minidoka, Jerome, and Gooding Counties also were analyzed for nutrients, tritium, chlorofluorocarbons, deuterium, oxygen-18, and nitrogen-15 to establish background values.

The land-use study conducted in the eastern Jerome County area provided additional information on ground-water quality changes from the southern Minidoka County area (irrigated primarily with ground water) downgradient to the western Jerome-southern Gooding Counties area (irrigated primarily with surface water). Samples from 15 wells were analyzed for major ions, nutrients, semivolatile organic compounds, and pesticides. Samples from 10 of the 15 wells also were analyzed for tritium, chlorofluorocarbons, deuterium, oxygen-18, nitrogen-15, and nitrate-nitrogen-15/oxygen-18.

As part of the study-unit survey to assess current ground-water quality conditions, samples from 50 wells in the Snake River Plain in 1994 and 40 wells in the northern and southern tributary valleys to the Snake River Plain in 1995 were analyzed for targeted pesticides and semivolatile organic compounds. These samples supplemented other samples collected and analyzed as part of the Idaho Statewide Ground-Water Quality Monitoring Network, a cooperative USGS/Idaho Department of Water Resources program. Samples from 20 wells in the eastern tributary valley (Jackson, Wyoming) area also were analyzed in 1995 for major ions, nutrients, semivolatile organic compounds, and pesticides.

Planned Groundwater Activites, 1997-2001

For selected land-use studies completed during 1993 ­ 95, two upgradient wells (reference wells) and two downgradient wells are planned to be sampled once per year. Two springs, Blue Lakes Spring in the upper part of the middle Snake River reach (representing local recharge) and Box Canyon Spring in the lower part of the middle Snake River reach (representing regional recharge), are planned to be sampled once per year. A total of 14 samples per year are planned to be collected and analyzed for major ions, nutrients, and pesticides. Data will be compiled, re-viewed, and published in the USGS annual Water-Resources Data report for Idaho.

Ground-water quality monitoring for the study-unit survey is closely coordinated with the Idaho Statewide Ground-Water Quality Monitoring Network, for which 400 wells are sampled annually. Land-use study monitoring also will be closely coordinated with the regional component of this program. Data collected for the statewide program will be used for the study-unit survey.

Completed Database and GIS Activities, 1991-1995

Data were documented and archived using a geographic information system (GIS) library and data base and USGS national and local data bases. Also, all water-quality and ecological data were aggregated regularly into the national data base. Study-unit personnel reviewed and assured that incoming field and analytical water-quality, aquatic biological, and habitat data were compiled into the established data bases. Updated environmental setting information was compiled, re-viewed, and aggregated regularly into established data bases.

Surface-water quality site locations, intensive ecological assessment site locations, ecological synoptic survey site locations, and land-use study area boundaries and sampling site locations were stored in a GIS library. Surficial geology, land use, precipitation quantity and quality, and other geographic data also were stored in the GIS library.

Planned Database and GIS Activities, 1997-2001

Planned activities include three major tasks. The first task will be to classify current thematic map scenes into land use and land cover and create GIS coverages of the classification for selected areas. The 1970's land-use data for the NAWQA Program are being updated using 1991 ­ 93 LANDSAT Thematic Map satellite scenes. Guidelines were established to produce a consistent national classification of land cover, which was further refined into land-use classifications that are relevant to the upper Snake River Basin. The second task will be to compile, review, and store incoming geographic, water-quality, and ecological data collected during the low-intensity phase. The third task will be to assure that incoming data are aggregated into the USGS national data base.

Publications

Clark, G.M., 1994, Assessment of selected constituents in surface water of the upper Snake River Basin, Idaho and western Wyoming, water years 1975 ­ 89: U.S. Geological Survey Water-Resources Investigations Report 93 ­ 4229, 49 p.

Clark, G.M., 1996, Occurrence of pesticides in surface water in the Rock Creek Basin, south- central Idaho: Moscow, Idaho Academy of Science Journal, December 1994, no. 252, p. 61 ­ 74.

Clark, G.M., 1997, Assessment of nutrients, suspended sediment, and pesticides in surface water of the upper Snake River Basin, Idaho and western Wyoming, water years 1991 ­ 95: U.S. Geological Survey Water-Resources Investigations Report 97­4020, 45 p.

Clark, G.M., in press, Occurrence and flux of selected pesticides in surface water of the upper Snake River Basin, Idaho and western Wyoming: Journal of Soil and Water Conservation.

Clark, G.M., and Ott, D.S., 1996, Springflow effects on chemical loads in the Snake River, south-central Idaho: Journal of the American Water Resources Association, v. 32, no. 3, p. 553 ­ 563.

Low, W.H., 1991, National Water-Quality Assessment Program - the upper Snake River Basin study: U.S. Geological Survey Water Fact Sheet, Open-File Report 91 ­ 165.

Mann, L.J., and Low, W.H., 1995, Tritium, stable isotopes, and nitrogen in flow from selected springs that discharge to the Snake River, Twin Falls-Hagerman area, Idaho, 1990 ­ 93: U.S. Geological Survey Water-Resources Investigations Report 94 ­ 4247, 21 p.

Maret, T.R., 1995, Mercury in streambed sediment and aquatic biota in the upper Snake River Basin, Idaho and western Wyoming, 1992: U.S. Geological Survey Fact Sheet, FS ­ 089 ­ 95.

Maret, T.R., 1995, Water-quality assessment of the upper Snake River Basin, Idaho and western Wyoming-summary of aquatic biological data for surface water through 1992: U.S. Geological Survey Water-Resources Investigations Report 95 ­ 4006, 59 p.

Maret, T.R., and Low, W.H., 1995, Drawing a "big picture" of Idaho waters: Boise, Idaho Department of Fish and Game, Idaho Wildlife, Fall 1995, p. 12 ­ 16.

Maret, T.R., Robinson, C.T., and Minshall, G.W., 1997, Fish assemblages and environmental correlates in least-disturbed streams of the upper Snake River Basin: Transactions of the American Fisheries Society, v. 126, no. 2, p. 200 ­ 216.

Maupin, M.A., 1995, Water-quality assessment of the upper Snake River Basin, Idaho and western Wyoming-environmental setting, 1980 ­ 92: U.S. Geological Survey Water-Resources Investigations Report 94 ­ 4221, 35 p.

Maupin, M.A., 1996, Estimated water use at dairy farms in Gooding, Jerome, and Twin Falls Counties, Idaho, 1990 ­ 93: U.S. Geological Survey Fact Sheet, FS ­ 111 ­ 96.

Rupert, M.G., 1994, Analysis of data on nutrients and organic compounds in ground water of the upper Snake River Basin, Idaho and western Wyoming, 1980 ­ 91: U.S. Geological Survey Water-Resources Investigations Report 94 ­ 4135, 40 p.

Rupert, M.G., 1996, Major sources of nitrogen input and loss in the upper Snake River Basin, Idaho and western Wyoming, 1990: U.S. Geological Survey Water-Resources Investigations Report 96 ­ 4008, 15 p.

Rupert, M.G., Stone, M.A.J., and Ott, D.S., 1996, National Water-Quality Assessment Program-nitrate and pesticides in ground water-Blaine, Cassia, Lincoln, and Minidoka Counties, south-central Idaho: U.S. Geological Survey Fact Sheet, FS ­ 246 ­ 95.

Selected Reading

Brennan, T.S., Jones, M.L., O'Dell, I., Lehmann, A.K., and Tungate, A.M., 1994, Water resources data, Idaho, water year 1994, Volume 1, Great Basin and Snake River Basin above King Hill: U.S. Geological Survey Water-Data Report ID ­ 94 ­ 1, 409 p.

Gilliom, R.J., Alley, W.M., and Gurtz, M.E., 1995, Design of the National Water-Quality Assessment Program - occurrence and distribution of water-quality conditions: U.S. Geological Survey Circular 1112, 33 p.

First posted 1997

For additional information contact:
Director, Idaho Water Science Center
U.S. Geological Survey 230 Collins Road
Boise, ID 83702
http://id.water.usgs.gov


Suggested citation:

Low, W. H, 1996, Activities of the National Water-Quality Assessment Program in the upper Snake River Basin, Idaho and western Wyoming, 1991-2001: U.S. Geological Survey Fact Sheet 198-96, 1 sheet.



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