News Release

Historical Mining Continues to Impact Grand Lake O’ the Cherokees

It has been more than 30 years since the lead and zinc mining ended in the Tri-State Mining District in southeast Kansas, southwest Missouri, and northeast Oklahoma.  However, past mining activity has  continued to result in the deposition of contaminated sediment in Grand Lake O’ the Cherokees (Grand Lake) with cadmium, lead, and zinc concentrations much greater than background concentrations as well as the threshold-effects concentrations above which adverse biological effects occasionally occur.  The mining-related contamination has adversely affected biota including mussels and waterfowl.  Grand Lake is a large reservoir on the Grand River in northeast Oklahoma, with primary tributaries to the reservoir being the Spring and Neosho Rivers.

Typically, zinc concentrations in the bottom sediment of Grand Lake exceeded the general probable-effects concentration (459 parts per million) by an average of about 60 percent. The probable-effects concentration is the level above which adverse biological effects usually or frequently occur.  Cadmium and lead concentrations were much less than the general probable-effects concentrations. Cadmium, lead and zinc concentrations were much less than the Tri-State specific probable-effects concentrations.

Lead and zinc depositional profiles indicated that concentrations in the bottom sediment of Grand Lake have decreased since about the 1980’s, when the inflow concentrations were at a maximum.

The results are from a one-year study done by the U.S. Geological Survey, in cooperation with the U.S. Fish and Wildlife Service.   The study provides information needed to assess the ecological health of Grand Lake.  "The study has shown that, even though major mining activity upstream of Grand Lake had ended by the 1970s, the sediment delivered to the lake today is still contaminated with cadmium, lead, and zinc,” said Kyle Juracek, project chief.  “The mining-related contamination is a long-term problem in the basin.”

The baseline of information on Grand Lake conditions provided in this report can be used for comparison with future conditions that may represent a response to changes in mining-related activities in the Grand Lake Basin.

The new Grand Lake O’ the Cherokees sediment quality report is only available online at:

http://pubs.usgs.gov/sir/2009/5258/