Trend: Downward trend in phosphorous levels in the Illinois River watershed but still exceeds Oklahoma’s limit for designated scenic rivers.
The Arkansas-Oklahoma Compact Commission received the annual Water Quality Monitoring Report for the Illinois River Basin for 2025 on September 17, 2026 in Siloam Springs, Arkansas.
Select portions of the report that are posted here for your information.
OAC COMM PHOSPHORUS LOADING AT WATTS, OK
OACO COM OKLA AVG PHOSPHORS LOADING 2026 REPORT
ORC COM 5 YEAR ROLLING AVG WATER QUALITY REPORT
OAC COMM COMPARISON OF SCENIC RIVERS PHOSPHORUS LIMIT
AOCC 2026 TRENDS IN WATER QUALITY
OAC COMM
AOCM 2026 WQ MONITORING STATIONS
This is the most significant report on the water quality of the Illinois River watershed available to the public and water quality regulators in both Arkansas and Oklahoma.
The full report may be available online from the Oklahoma Water Resource Board at a future date.
