Illinois Watershed - 11110103

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.

State-Level Map - Illinois Watershed-Level Map - Illinois Watershed Land Use Map - Illinois

County Pages
(Contact Information)

 Major Streams

 2006 Land Use
(754 Square Miles)

  • 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

Illinois 303d Impaired Streams (what is an impaired stream?)


Watershed Management Plan

IllinoisWMS/Illinois Update: January 18, 2005 


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


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 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 


  • Clean Water Act Section 303(d) Impaired Waters Data Update here
  • Arkansas’s Final/ Draft Impaired Waterbodies – 303(d) List by Year here
  • AR Water Newsletter, Summer, 2015 here
  • NPS Management Plan here
  • The projects presented at the 2015 annual NPS conference are located here

Interactive Map

Interactive Watershed Viewer
Explore your county or watershed with this flash-based interactive map.  View over 25 geographic and water-related layers. Open Interactive Watershed Viewer.