Land and water use have altered stream quality in the central
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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