Introduction

The California Regional Water Quality Control Board, San Diego Region (Regional Board) is in the process of addressing water quality impairments in Chollas Creek and the mouth of Chollas Creek in San Diego Bay. The Chollas Creek watershed has been selected as one of the first TMDLs to be developed by the Regional Board. There are currently two TMDL projects underway in the Chollas Creek watershed and one being planned.

• Chollas Creek – Metals
• Chollas Creek – Diazinon
• Mouth of Chollas Creek in San Diego Bay – benthic community degradation and sediment toxicity (in planning stage).

Chollas Creek was placed on the 303(d) list of "water quality limited" waterbodies in 1998 because metals, toxicity, and coliform data indicate that beneficial uses are being impaired. According to data collected under the San Diego Municipal NPDES storm water permit, storm water runoff in Chollas Creek contains concentrations of cadmium, copper, lead, and zinc which impair aquatic life beneficial uses. Chollas Creek storm water runoff also causes toxicity to Ceriodaphnia.

San Diego Bay at the mouth of Chollas Creek is on the 303(d) list for benthic community degradation and toxicity in the sediment. Sediment from three stations at the mouth of Chollas Creek at its confluence with San Diego Bay were analyzed under the Bay Protection and Toxic Cleanup Program (BPTCP) and exhibited degraded benthic communities. This condition supported listing of this area on the 303(d) list and also the designation of this area as a candidate toxic hot spot in the Regional Toxic Hot Spot Cleanup Plan. Although the cause of the benthic community degradation is not known, chlordane is present in elevated concentrations at the three BPTCP stations.

Available Data for Chollas Creek