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0553 aqu~=ic life standard. The increase in dissolved selenium is similar to =ie total selenium concentration trend. The ~aximum selenium concentration detected in fish from the stream sites was 18.5 micrograms/gram in a sample of common acarp from the Arka~sas River near Lamar, Colorado guaging station. 2/ Five species of :ish in the Arkansas River had selenium concentrations ranging from 2.1 co 18.5 micrograms/gram. Three species in the tributaries had sele~ium concentrations ranging from 3.6 to 16.9 micrograms/gram. All but 3 of the 59 total fish samples exceeded the 85th percentile nat~onal baseline for selenium in fish (2.45 micrograms/gram dry weiqit), and 21 of the samples had concentrations exceeding the range asscciated with reproductive failure in bluegill. About one-half of the samples had selenium concentrations that exceeded the dietary concentration known to increase the rate of mortalities and deformities in ~allard embryos. Selenium levels in aquatic plants exceeded accs?table dietary limits of avion species. Sele~ium concentrations in surface water was 1 microgram/liter in Pue~lo Reservoir upstream from the project area. Data from EPA, STORET dataoase, indicates that the stretch of the Arkansas River from below Joh~ Martin Reservoir to Lamar, Colorado, has significant higher levels of selenium. 117 Samples taken indicated average total selenium concentration increases from 7.2 micrograms/liter to 19.7 mic~ograms/liter between the two gage stations. The mean value of 19.7 mic~ograms/liter total selenium was determined using 96 values from 1962 to 1994. Add~tional USGS outflow data from John Martin Reservoir indicates a tre~d in increased selenium concentrations. Data from 1980 and 1981 tha= was used with comparison data from 1988 through 1993 indicates tha= dissolved selenium is increasing by .2 micrograms/liter annually. The trend indicates that selenium standards for agriculture use, 20 mic~ograms/liter, will be exceeded in the near future. Alt~ough the project was not formulated to reduce other toxic trace ele~ents or heavy metals, project action will help reduce those proclems and improve water quality. Dissolved uranium levels of the Arkansas River are also increasing. Uranium ingested by humans and wildlife goes to both the kidneys and bone. It is a chemical poison to the kidneys. Kidney inflammation and failure can occur. Sam~ling of the Arkansas River from Manzanola to Lamar found that dissolved uranium increases at a much higher rate than in the upper reaches. An abrupt increase in dissolved uranium is observed along the sec=~on of river where flow is greatly reduced because of extensive dive=sions for irrigation and the remaining flow is largely composed of irr~gation return water. Water samples in this section of river are more enriched in dissolved uranium compared to the average concentration found in water outside the irrigated areas. The mean concentration of uranium in ground water was 19.4 micro gra~s/liter for uranium in the Lamar Quadrangle of Southeastern Colorado (825 samples). Wells of less than 100 feet depth were' 15 I I I I I I I I I I I I I I I I I I I