News Release

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Streambed Sediment Affects Water Quality in Little Arkansas River Basin

Nationally, states are required by the Clean Water Act of 1972 to improve the water quality of impaired water bodies through the implementation of total maximum daily loads (TMDLs).  A TMDL is an estimate of the maximum pollutant load from point and nonpoint sources that a receiving water can accept without exceeding water quality standards.   In Kansas, the Little Arkansas River Basin is listed as a high priority TMDL basin.

A recent study completed by the U.S. Geological Survey (USGS), in cooperation with the Kansas Department of Health and Environment (KDHE), investigated the variability in streambed-sediment quality and its relation to historical water quality. 

Specifically, the study identified “hot spots” where contaminant concentrations in the streambed sediment were larger and possibly related to human activity.  For example, the largest nitrogen concentrations were measured for two sediment samples collected in the Emma Creek subbasin, which has a relatively greater density of livestock and poultry production. Animal waste is a known source of nitrogen which affects water quality.

Trace element concentrations in the streambed sediment varied from site to site and typically were less than threshold-effects guidelines for possible adverse biological effects.  The largest copper, lead, silver, and zinc concentrations, likely related to urban sources of contamination, were measured for a streambed sediment sample collected from Sand Creek downstream from Newton, Kansas.

Nitrogen and phosphorus concentrations in both the water and streambed sediment samples typically decreased as streamflow increased. This may be because more sediment is coming from the erosion of channel banks, which contain fewer nutrients than surface soils.

According to Kyle Juracek, project leader, if flow conditions are considered, it may be possible to use streambed sediment as an indicator of water quality for nitrogen and phosphorus. The information provided by this study will provide guidance to KDHE for the prioritization and development of TMDLs and the implementation of best-management practices in the basin.

The report is now available online at:

 http://pubs.usgs.gov/sir/2008/5187/

More information about sediment studies in Kansas can be found at:

http://ks.water.usgs.gov/studies/sedsci/

USGS provides science for a changing world. For more information, visit www.usgs.gov. Subscribe to USGS News Releases via our electronic mailing list or RSS feed.

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