California Code of Regulations › Title 23 - Waters › Division 4 - Regional Water Quality Control Boards › Chapter 1 - Water Quality Control Plans, Policies, and Guidelines › Article 4 - Los Angeles Region › Section 3939.48 - A Total Maximum Daily Load for Indicator Bacteria in the San Gabriel River, Estuary and Tributaries

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
On June 10, 2015, the Los Angeles Regional Water Quality
					 Control Board (Los Angeles Water Board) adopted Resolution No. R15-005,
					 amending the Water Quality Control Plan for the Los Angeles Region (Basin Plan)
					 to incorporate a total maximum daily load (TMDL) for indicator bacteria in the
					 San Gabriel River, Estuary and tributaries. The State Water Resources Control
					 Board (State Water Board) approved the amendment under Resolution No. 2015-0067
					 on November 17, 2015.
The TMDL sets numeric targets for indicator bacteria based
					 on numeric water quality objectives provided in the Basin Plan. The TMDL
					 assigns waste load allocations (WLAs) and load allocations (LAs) to municipal
					 separate storm sewer system (MS4) discharges, other non-MS4 National Pollutant
					 Discharge Elimination System (NPDES) discharges, and nonpoint source discharges
					 to attain water quality objectives for bacteria set to protect public health
					 based on the water contact recreation and non-contact recreation beneficial
					 uses of these waterbodies.
There are two types of numeric targets: single sample
					 limits and geometric mean limits. Final allocations to achieve the single
					 sample limits numeric targets are expressed as "allowable exceedance days" and
					 only apply to days in which single sample limits are exceeded and do not apply
					 to days where geometric mean limits are exceeded. Allowable exceedance days are
					 further separated into two time periods (1) dry weather and (2) wet weather for
					 San Gabriel River and its tributaries and into three time periods (1) summer
					 dry-weather, (2) winter dry-weather, and (3) wet-weather for San Gabriel River
					 Estuary. No exceedance days of the geometric mean targets are allowed at any
					 time. The TMDL requires the MS4 dischargers and nonpoint source dischargers to
					 achieve the final WLAs and LAs within 10 years for the dry-weather and 20 years
					 for the wet-weather condition.
Compliance with the MS4 WLAs is assessed through compliance
					 with MS4 permits. The MS4 WLAs will be implemented by permittees through their
					 Watershed Management Programs or Enhanced Watershed Management Programs, which
					 have to be approved by the Los Angeles Water Board. Compliance with the WLAs
					 assigned to non-MS4 point source dischargers is assessed through NPDES permits
					 with effluent limits for bacteria that are equal to the existing effluent
					 limits for bacteria. Non-MS4 dischargers that do not have existing effluent
					 limits for bacteria are not assigned WLAs. If reasonable potential analysis
					 during the permitting process indicates a reasonable potential for the
					 discharge to be a source of bacteria, then effluent limits must be included in
					 the permit.
Compliance with the LAs is assessed through compliance with
					 the Conditional Waiver for Irrigated Lands (Order No. R4-2010-0186 or other
					 successor order), Waste Discharge Requirements, Waivers of Waste Discharge
					 Requirements, Memoranda of Understanding or other appropriate mechanisms
					 consistent with the State Water Board's Nonpoint Source Implementation and
					 Enforcement Policy.
1. New
					 section summarizing amendments to basin plan filed 4-14-2016; amendments
					 approved by State Water Resources Control Board Resolution No. 2015-0067 on
					 11-17-2015; amendments approved by OAL pursuant to Government Code section
					 11353 on
					 4-14-2016 (Register 2016, No. 16).