In March 1999, the Santa Ana Regional Water Quality Control Board adopted a TMDL for sediment intended to reduce sediment impacts over a multi-year period. The objectives of the TMDL are to reduce the annual average sediment load in the San Diego Creek watershed from a total of 250,000 tons per year to 125,000 tons per year, calculated over a ten year period (a 50% reduction). In addition, the 125,000 tons per year annual average sediment load target is allocated equally between the San Diego Creek watershed (62,500 tons per year) and the Newport Bay watershed (62,500 tons per year). The Sediment TMDL also aims to reduce the frequency of dredging within Upper Newport Bay.

On November 19, 1999, the Santa Ana Regional Water Quality Control Board subsequently adopted Monitoring and Reporting Program No. 99-74 which requires monitoring and reporting in accordance with the requirements of the Sediment TMDL. The sediment monitoring and maintenance program consists of two study area elements: (1) the Upstream Monitoring Element which includes those activities performed in the San Diego Creek watershed upstream of Jamboree Road Bridge and in the Santa Ana-Delhi Channel, and (2) the Newport Bay Monitoring Element which includes those activities performed in the Upper and Lower Newport Bay.

The Upstream Monitoring Element consists of monitoring the sediment holding capacities of the three in-channel basins and seven foothill basins. In addition, fluvial sediment samples and streamflow data are collected from eight monitoring stations, which are located at:

• Peters Canyon Wash at Barranca Parkway
• San Diego Creek at Culver Drive
• San Diego Creek at Campus Drive
• Santa Ana-Delhi at Irvine Avenue
• Sand Canyon Channel at University Drive
• Bonita Canyon Creek at MacArthur Boulevard
• Marshburn Channel at Trabuco Road
• Agua Chinon Channel at Irvine Boulevard

The Newport Bay Monitoring Element consists of conducting vegetative and bathymetric surveys as needed, removal of sediment from the in-bay basins as needed, and fluvial sediment and flow monitoring during storm events.

An annual report is submitted to the Santa Ana Regional Water Quality Control Board by November 15 of each year, verifying that the basins have at least 50% design capacity available for the upcoming storm season. The TMDL Annual Report (a compilation of sediment monitoring data and TMDL compliance analysis) is delivered to the Regional Board by December 31 of each year.

Sediment TMDL Documents

Annual Reports

Special Studies