Home to approximately 200,000 Arkansans (2000 Census), the Illinois (see poster) watershed lies within the Arkansas River Basin in Northwest Arkansas crossing into Oklahoma.  The hydrologic unit code for this watershed is 11110103. There is no upstream watershed.  The Dirty-Greenleaf Watershed (Oklahoma) is downstream.
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County Pages (Contact Information)	Major Streams	2006 Land Use (754 Square Miles)
Benton Crawford Washington	Ballard Creek Baron Fork Cincinnati Creek Clear Creek Clear Creek Evansville Creek Flint Creek Illinois River Moores Creek Muddy Fork Osage Creek	Grassland: 50.3% Forest: 35.9% Suburban: 4.5% Urban: 4.3% Transitional: 4.3% Water: 0.3% Cropland: 0.0% Data Source: CAST

Watershed Management Plan

IllinoisWMS/Illinois Update: January 18, 2005 

Total Maximum Daily Load (TMDL) Documents (what is a TMDL?)

• Water Quality Survey and Biological Assessment of the Effects of Wastewater Discharges from the City of Siloam Springs on Sager Creek. ADEQ Water Division in cooperation with the Oklahoma Water Resources Board, 1995, 54 p.
• Illinois River Water Quality, Macroinvertebrate and Fish Community Survey, Status Report. ADEQ Water Division, 1995, 8 p. + appendices.
• Illinois River Water Quality, Macroinvertebrate and Fish Community Survey, Benton and Washington Counties, Arkansas. ADEQ Water Division, 1997, 90 p.
• TMDL Investigation of Water Quality Impairments to Town Branch, McKisic, and Little Sugar Creeks, Benton County, Arkansas. ADEQ Water Division, 1997, 31 p.

More Watershed-Related Information

• CAST Arkansas Watershed Information System:  Illinois
• EPA Surf Your Watershed:  Illinois
• USGS Real Time Stream Flow:  Illinois
• All Upstream & Downstream Watersheds:  Illinois
• USGS Links to Water Quality & Groundwater Monitoring Sites:  Illinois
• Environmental Statistics Group (Montana State University):  Illinois
• Ballard Creek Conservation Project - Washington County Conservation District
• Audubon Arkansas:  Important Bird Area
• Illinois River Watershed Partnership: seeking to restore and maintain the quality of the Illinois River.  Contact Delia Haak at 479-238-4671 or at This email address is being protected from spambots. You need JavaScript enabled to view it. .  Visit http://www.irwp.org for more information.
• Arkansas Watershed Advisory Group (Spring 2006) - Featured Watershed: Illinois River Watershed - "The Illinois River is a valuable natural resource that originates in Arkansas and flows into Oklahoma where it is designated as a Scenic River"... more on Page 2