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 3939.2 - A Total Maximum Daily Load for Nitrogen Compounds and Related Effects in Calleguas Creek, Its Tributaries, and Mugu Lagoon

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
Los Angeles Regional Water Quality Control Board (Regional
					 Board) Resolution No. 02-017, adopted on October 24, 2002 by the Regional
					 Board, modified the regulatory provisions of the Water Quality Control Plan for
					 the Los Angeles Region by establishing a Total Maximum Daily Load (TMDL) for
					 nitrogen compounds in Calleguas Creek, its tributaries, and Mugu Lagoon. The
					 TMDL specifies concentration-based targets for ammonia, nitrate, nitrite, and
					 combined nitrate and nitrite, which must be fully attained seven years after
					 the effective date of the TMDL. The TMDL includes a margin of safety with both
					 implicit and explicit components. The TMDL establishes a four-year plan for
					 reducing nitrogen loading from five wastewater treatment plants in the
					 watershed. To allow time to meet the targets, interim limits will be allowed.
					 The final wasteload allocations (WLAs) for ammonia assigned to the wastewater
					 treatment plants must be met no later than October 24, 2004, and the final
					 wasteload allocations for nitrate and nitrite must be met four years after the
					 effective date of the TMDL. Load allocations for agriculture and other nonpoint
					 source discharges are implemented through various management practices. One
					 year after the effective date of the TMDL, monitoring plans to evaluate the
					 effectiveness of the TMDL must be submitted to the Regional Board by Calleguas
					 Creek Watershed Management Plan Water Resources/Water Quality Subcommittee
					 (CCWMP). CCWMP is responsible for the watershed monitoring and special studies
					 required by this TMDL. The special studies must be completed five years after
					 the effective date of the TMDL.
In preparing the NPDES permit renewals, Regional Board
					 staff identified a typographical error in the mass based daily WLAs for ammonia
					 in the Calleguas Creek Nitrogen Compounds and Related Effects TMDL. Translating
					 concentration based limit into a mass based daily limit requires multiplying
					 the concentration-based limit by the flow rate. The mass based daily WLAs for
					 ammonia, however, were incorrectly calculated as the product of the daily flow
					 rate and the average monthly effluent limits (AMEL), rather than the daily flow
					 rate and the maximum daily effluent limits (MDEL).
The TMDL was revised and then adopted by the Regional Board
					 under Resolution No. R4-2008-009 to correct the mass based daily WLAs for
					 ammonia to be based upon the MDEL, and updates the WLAs to be consistent with
					 the current practice of recognizing that flow is variable. The mass based WLAs
					 for ammonia are corrected to be based on the maximum daily effluent limit,
					 MDEL, and the actual discharger effluent flow rate at the time the monitoring
					 is conducted.
1. New
					 section summarizing amendments to Water Quality Control Plan filed 6-5-2003;
					 amendments adopted by the Los Angeles Regional Water Quality Control Board
					 10-24-2002 per Resolution No. 2002-017. Approved by State Water Resources
					 Control Board 4-10-2003; approved by OAL and effective 6-5-2003 pursuant to
					 Government Code section
					 11353
					 (Register 2003, No. 23).
2. Amendment of first paragraph and new
					 second and third paragraphs summarizing changes to Basin Plan filed 9-30-2009;
					 amendments adopted by the Los Angeles Regional Water Quality Control Board
					 9-11-2008 by Resolution No. R4-2008-009. Approved by State Water Resources
					 Control Board 6-16-2009 by Resolution No. 2009-0052; amendment approved by OAL
					 9-30-2009 pursuant to Government Code section
					 11353
					 (Register 2009, No. 40).