About EPA
Illinois River Watershed
Illinois River Watershed | Region 6 Water Programs | US EPA
The Illinois River is a multi jurisdictional tributary of the Arkansas River, approximately 100 miles (160) km) long, between the States of Arkansas and Oklahoma. The Illinois River begins in the Ozark Mountains in the northwest corner of Arkansas (Washington County) and flows west into northeast Oklahoma. Once the Illinois River enters Oklahoma, it then flows southwest and south through the mountains of eastern Oklahoma into Tenkiller Ferry Lake. The Illinois River in Oklahoma is currently on the 303(d) list for total phosphorus, while tributaries to the Illinois River (e.g. Osage Creek, Muddy Fork, and Spring Creek) in Arkansas are also on the 303(d) list for total phosphorus.
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Current Phase – Watershed and Lake Calibration/Validation Modeling The calibration/validation modeling is currently being conducted for both Illinois River and Lake Tenkiller. The purpose of the calibration/validation modeling is to ensure a scientifically sound modeling system is developed to represent the entire Illinois River Watershed. Calibration modeling will be performed for the time period of 2001 to 2009, whereas the period of 1992 to 2000 will be used for validation modeling. Calibration and validation of the Illinois River Watershed models will be achieved by considering qualitative and quantitative measures, involving both graphical comparisons and statistical tests. |
Upcoming Events and Activities
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You will need Adobe Acrobat Reader, available as a free download, to view these files. See EPA's PDF page to learn more about PDF, and for a link to the free Acrobat Reader. |
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April 26, 2012 Meeting
May 19, 2011 Meeting
January 6, 2011 Meeting
September 14, 2010 Meeting
February 4, 2010 Meeting
November 20, 2009 Meeting - Project Kickoff Meeting
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National Information
- Federal Register Notice- Call for Data
- TMDL Program
- Illinois River Watershed TMDLs (coming soon)