Land and water use have altered stream quality in the central Nebraska basins

September 1996

U.S. Water News Online

GRAND ISLAND, Neb. -- Stream quality in the central Nebraska basins has been altered by land and water use, according to a new report by the U.S. Geological Survey (USGS).

The report, Science for a Sustainable Future of the Great Plains: Water Quality Assessment in Central Nebraska, was written by Thomas L. Huntzinger and John K. Stamer as part of the USGS National Water-Quality Assessment Program. This was a multidisciplinary study undertaken jointly by the USGS and the Great Plains Working Group.

The report includes the following findings:

• The width of the Platte River near Grand Island has narrowed overthe past 30 years, a typical problem on much of the Platte. As a result, many of the sand bars in the river have become permanently vegetated. This has decreased the amount of suitable habitat for endangered bird species and other migratory birds, such as cranes and the Piping Plover.
  
• Fish species commonly found at sites in the study area were relatedto the amount of cropland within the drainage area and the amount of orthophosphate, an ingredient in fertilizer, in the stream water. Tolerant species, such as the Yellow bullhead and Fathead minnow, were commonly found in streams that drain mostly cropland. Intolerant species, such as the small-mouthed bass, were commonly found in streams that drained rangeland.
  
• Nitrate concentrations in shallow water were significantly largerthan in deeper wells. The largest concentration of nitrate occur in the shallow wells in the Platte River Valley. The nitrate concentrations in the Platte River Valley generally exceeded drinking water regulations, which caused public utilities to seek deeper sources of groundwater, containing less nitrate.
  
• The largest concentrations of commonly-applied agriculturalherbicides, such as atrazine and cyanazine, often occur in the Platte River during spring runoff. Data collected indicate that the annual mean concentration of cyanazine exceeded the Health Advisory Level of 1.0 microgram per liter at the Platte River at Louisville.
  

This USGS Open-File Report 96-140 is available on request from: U.S. Geological Survey, Branch of Information Services, Box 25286, Denver, CO 80225

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