U.S. Geological Survey Water-Resources Investigations Report 99-4230
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Deposition of Selenium and Other Constituents in Reservoir Bottom Sediment of the Solomon
River Basin, North-Central Kansas
By V.G. Christensen
Abstract
The Solomon River drains approximately 6,840 square miles of mainly agricultural land in
north-central Kansas. The Bureau of Reclamation, U.S. Department of the Interior, has begun a
Resource Management Assessment (RMA) of the Solomon River Basin to provide the necessary data
for National Environmental Policy Act (NEPA) compliance before renewal of long-term
water-service contracts with irrigation districts in the basin. In May 1998, the U.S.
Geological Survey (USGS) collected bottom-sediment cores from Kirwin and Webster Reservoirs,
which are not affected by Bureau irrigation, and Waconda Lake, which receives water from both
Bureau and non-Bureau irrigated lands. The cores were analyzed for selected physical
properties, total recoverable metals, nutrients, cesium-137, and total organic carbon.
Spearman's rho correlations and Kendall's tau trend tests were done for sediment
concentrations in cores from each reservoir. Selenium, arsenic, and strontium were the only
constituents that showed an increasing trend in concentrations for core samples from more
than one reservoir. Concentrations and trends for these three constituents were compared to
information on historical irrigation to determine any causal effect. Increases in selenium,
arsenic, and strontium concentrations can not be completely explained by Bureau irrigation.
However, mean selenium, arsenic, and strontium concentrations in sediment from all three
reservoirs may be related to total irrigated acres (Bureau and non-Bureau irrigation) in the
basin. Selenium, arsenic, and strontium loads were calculated for Webster Reservoir to
determine if annual loads deposited in the reservoir were increasing along with constituent
concentrations. Background selenium, arsenic, and strontium loads in Webster Reservoir are
significantly larger than post-background loads.
Christensen, V.G., 1999, Deposition of Selenium and Other Constituents in Reservoir
Bottom Sediment of the Solomon River Basin, North-Central Kansas [abst.]: U.S. Geological
Survey Water-Resources Investigations Report 99-4230, 46 p.
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email: GS-W-KS_info@usgs.gov
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