Middle Santa Ana River Bacteria TMDL

The MSAR Bacteria TMDL was established due to bacterial contamination in: Santa Ana River, Reach 3; Chino Creek, Reaches 1 and 2; Mill Creek (Prado Area); Cucamonga Creek, Reach 1; and Prado Park Lake.

The MSAR Bacteria TMDL was adopted on August 26, 2005, through Resolution R8-2005-0001. They were then approved by the Office of Administrative Law (OAL) on September 1, 2006, followed by the US Environmental Protection Agency on (US EPA) May 16, 2007.

March 13, 2026 - Board Hearing

MSAR TMDL Response to Public Comments

Errata Change Sheet

Signed Resolution No. R8-2026-0014

Final TMDL Technical Report: Proposed Revisions to the Middle Santa Ana River Watershed Bacterial Indicator TMDLs

Final Amendment to the Santa Ana Region Basin Plan

January 27, 2026 to February 2026 - Public Comment Period

TMDL Technical Report: Proposed Revisions to the Middle Santa Ana River Watershed Bacterial Indicator TMDLs

Tentative Resolution No. R8-2026-0014

Draft Amendment to the Santa Ana Region Basin Plan - Clean

Draft Amendment to the Santa Ana Region Basin Plan - Redline

Notice of Public Hearing and Comment Period

Aviso De Audiencia Publica Y Periodo De Comentarios

January 9, 2023 - CEQA Scoping

CEQA Scoping Meeting Public Notice

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For more information, please contact Lauren Hubbell at (951) 320-6375