Hydrologists, U.S. Geological Survey, Denver Federal Center, Mail Stop 415, Lakewood, Colorado 80225.
GROUND WATER AS A SOURCE OF NUTRIENTS AND ATRAZINE TO STREAMS IN THE SOUTH PLATTE RIVER BASIN†
Article first published online: 8 JUN 2007
JAWRA Journal of the American Water Resources Association
Volume 30, Issue 3, pages 521–530, June 1994
How to Cite
McMahon, P. B., Litke, D. W., Paschal, J. E. and Dennehy, K. F. (1994), GROUND WATER AS A SOURCE OF NUTRIENTS AND ATRAZINE TO STREAMS IN THE SOUTH PLATTE RIVER BASIN. JAWRA Journal of the American Water Resources Association, 30: 521–530. doi: 10.1111/j.1752-1688.1994.tb03310.x
Paper NO. 93149 of the Water Resources Bulletin. Discussions are open until February 1, 1995.
- Issue published online: 8 JUN 2007
- Article first published online: 8 JUN 2007
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ABSTRACT: Concentrations of nitrite plus nitrate, ammonia, orthophosphate, and atrazine were measured in streams and ground water beneath the streams at 23 sites in the South Platte River basin of Colorado, Nebraska, and Wyoming to assess: (1) the role of ground water as a source of nutrients and atrazine to streams in the basin, and (2) the effect of land-use setting on this process. Concentrations of nitrite plus nitrate, ammonia, orthophosphate, and atrazine were higher in ground water than in the overlying streams at 2, 12, 12, and 3 of 19 sites, respectively, where there was not a measurable hydraulic gradient directed from the stream to the ground water. Orthophosphate was the only constituent that had a significantly higher (p ≤ 0.05) concentration in ground water than in surface water for a given land-use setting (range land). Redox conditions in ground water were more important than land-use setting in influencing whether ground water was a source of elevated nitrite plus nitrate concentrations to streams in the basin. The ratios of nitrite plus nitrate in ground water/surface were were significantly lower (p ≤ 0.05) at sites having concentrations of dissolved oxygen in ground water ≤ 0.5 mg/L than at sites having dissolved oxygen concentrations ≥ 0.5 mg/L. Elevated concentrations of ammonia or atrazine in ground water occurred at sites in close proximity to likely sources of ammonia or atrazine, regardless of land-use setting. These results indicate that land-use setting is not the only factor that influences whether ground water is a source of elevated nutrient and atrazine concentrations to streams in the South Platte River Basin.