San Diego Region - Chollas Creek TMDL for Metals
The California Water Quality Control Board, San Diego Region, adopted the Chollas Creek Metals TMDLs Basin Plan Amendment (TMDLs) on June 13, 2007. These TMDLs were approved by the State Water Resources Control Board through Resolution No. 2008-0054 on July 15, 2008. The State Office of Administrative Law (OAL) approved the TMDLs on October 22, 2008 as File No. 2008-0909-01 S. The United States Environmental Protection Agency approved the TMDLs on December 18, 2008. Based on the approval date from the OAL, the official commencement date for these TMDLs is October 22, 2008. The TMDL documents can be accessed below in the Public Documents section.
Chollas Creek is an urban creek with highly variable flows. Much of the Creek has been channelized and concrete lined, but some sections of earthen creek bed remain. The creek originates in the Cities of Lemon Grove and La Mesa. It flows approximately 15 miles downstream, through the City of San Diego, and empties on the eastern shoreline of the central portion of San Diego Bay. Urban runoff enters the Creek throughout its course and is the main cause of the observed conditions as described below.
Since 1994, Chollas Creek storm water samples have frequently exceeded the Basin Plan narrative water quality objective for toxicity. These samples have also exceeded chronic and acute water quality criteria for metals established in the California Toxics Rule. Specifically, during the period 1994 - 2001, concentrations of copper and zinc during storm events have frequently exceeded acute and chronic criteria, while concentrations of cadmium and lead have frequently exceeded chronic and periodically exceeded acute criteria. These conditions resulted in the Creek being placed on the CWA Section 303(d) list in 1996 for toxicity, cadmium, copper, lead and zinc. Cadmium was delisted by the State Water Board in the 2006 list update.
In 1999, Toxicity Identification Evaluations (TIEs) revealed the observed toxicity to be caused primarily by zinc and to a lesser extent by copper. The household pesticide diazinon was also identified as a cause of toxicity and is currently being addressed by a separate TMDL that was adopted by the San Diego Water Board in August 2002. This TMDL was developed to address the toxicity caused by metals to aquatic life in Chollas Creek.
How to Receive Updates on the Chollas Creek Metals TMDL
The San Diego Water Board would like to keep interested persons fully informed during the final approval process for Chollas Creek Metals TMDLs, including approval by the State Water Board, the OAL, and the USEPA. Updates on the Chollas Creek Metals TMDLs will only be sent to persons that specifically request this information. To receive updates from the San Diego Water Board, you must either: 1) subscribe to our electronic mailing list; or 2) send an email request to the contact person listed below to have information sent to you via U. S. Mail. You can subscribe to our electronic mailing list. You may also obtain information from our Website or by appointment at the San Diego Water Board office.
(All documents are in PDF format unless otherwise noted)
|State Water Resources Control Board Approval|
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- Melissa Corona - WRC Engineer