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Show 31 Appendix- Water- Quality Data from the Great Salt Lake Basins in a National Context Concentrations and detection frequencies of the most commonly detected constituents, constituents that exceed a drinking- water standard or aquatic- life guideline, or constituents that are of regulatory or scientific importance, are presented below. Plots of other pesticides, nutrients, VOCs, and trace elements assessed in the Great Salt Lake Basins are available at our Web site at: For example, the graph for atrazine shows that in the Great Salt Lake Basins ( 1) concentrations generally are lower than national findings in streams in all land use areas; ( 2) concentrations are not in violation of the USEPA drinking- water standard in streams and ground water; and ( 3) frequency of detection is lower in ground water than in surface water. http:// water. usgs. gov/ nawqa/ graphs These summaries of chemical concentrations and detection frequencies from the Great Salt Lake Basins are compared to findings from 51 NAWQA Study Units investigated from 1991 to 2001 and to water- quality benchmarks for human health, aquatic life, fish- eating wildlife, or prevention of nuisance plant growth. These graphical summaries provide a comparison of chemical concentrations and detection frequencies between ( 1) surface- and ground- water resources; ( 2) agricultural, urban, and mixed land uses; and ( 3) shallow ground water and aquifers commonly used as a source of drinking water. CHEMICALS IN WATER Concentrations and detection frequencies, Great Salt Lake Basins, 1999- 2001 • Detected concentration in Study Unit 66 38 Frequencies of detection, in percent. Detection frequencies were not censored at any common reporting limit. The left- hand column is the study- unit frequency and the right- hand column is the national frequency Not measured or sample size less than two -*•? Study- unit sample size. For ground water, the number of samples is equal to the number of wells sampled National ranges of detected concentrations, by land use, in 51 NAWQA Study Units, 1991- 2001- Ranges include only samples in which a chemical was detected Streams in agricultural areas Streams in urban areas Streams and rivers draining mixed land uses Shallow ground water in agricultural areas Shallow ground water in urban areas Major aquifers Lowest Middle Highest 25 50 25 percent percent percent National water- quality benchmarks National benchmarks include standards and guidelines related to drinking- water quality, criteria for protecting the health of aquatic life, and the desired goal for preventing nuisance plant growth due to phosphorus. Sources include the U. S. Environmental Protection Agency and the Canadian Council of Ministers of the Environment Drinking- water quality ( applies to ground water and surface water) | Protection of aquatic life ( applies to surface water only) | Prevention of nuisance plant growth in streams * No benchmark for drinking- water quality ** No benchmark for protection of aquatic life NOTE to users: • The analytical detection limit varies among the monitored chemicals, thus frequencies of detections are not comparable among chemicals. • It is important to consider the frequency of detection along with concentration. For example, atrazine was detected more frequently in mixed land use streams in the Great Salt Lake Basins than in mixed land use streams nationwide ( 100 percent compared to 90 percent), but generally was detected at lower concentrations. Quality control data for these analytes indicate relatively frequent low- level contamination of samples during sample processing for analysis. Results for these analytes cannot, therefore, be presented using the generalized methods that were applied to other analytes in this Appendix. Analysis of results for analytes potentially affected by contamination requires special statistical treatment beyond the scope of this report. For more information about these analytes and how to interpret data on their occurrence and concentrations, please contact the appropriate NAWQA Study Unit. Trace elements in ground water: aluminum, barium, boron, cadmium, chromium, cobalt, copper, lithium, nickel, strontium, zinc SVOCs in bed sediment: phenol, bis( 2- ethylhexyl) phthalate, butylbenzylphthalate, di- n- butylphthalate, diethylphthalate Insecticides in water: p, p'- DDE Pesticides in water- Herbicides Study- unit frequency of detection, in percent National frequency of detection, in percent Study- unit sample size ~~ i 1 1 r J_ Atrazine ( AAtrex, Atrex, Atred) 91 92 81 78 100 90 79 24 42 32 18 74 82 67 59 88 78 -- 42 75 32 31 20 Deethylatrazine ( Atrazine metabolite, desethylatrazine) • Prometon ( Pramitol, Princep, Gesagram 50, Ontracic 80) 72 95 46 84 ' fmmmwmwmi 100 62 -- 10 50 22 11 5 • • • • •• 1 23 43 12 0 28 55 23 45 42 0 28 55 25 44 42 0 30 55 0.001 0.01 0.1 1 10 100 CONCENTRATION, IN MICROGRAMS PER LITER |
