POWAY CITY COUNCIL TO DISCUSS LAGOON RESTORATION

364 acres of salt marsh must be restored by 2035

The Poway City Council will discuss the potential restoration of one of its watersheds, the Los Peñasquitos Lagoon, at 7 p.m. Tuesday.

The council will be asked to direct staff on how it wants to move forward with its involvement in a restoration project of salt marshes in the lagoon. The project is part of a joint-agency effort to reduce sediment in the watershed.

A watershed is an area of land that drains all streams and rainfall to one location. Poway is in two watersheds, Los Peñasquitos and San Dieguito, said Bob Manis, director of development services. The Los Peñasquitos Lagoon is a coastal marsh in San Diego County near Del Mar.

The lagoon was placed on the Clean Water Act list of impaired waterbodies for sedimentation and siltation in 1996, Manis said. The state is required to establish a total maximum daily load (TMDL) for pollutants in bodies of water on the list, he added. A TMDL establishes the maximum amount of a pollutant allowed in a waterbody and serves as the starting point or planning tool for restoring water quality, Manis said.

A TMDL for the lagoon was issued by the San Diego Regional Water Quality Control Board in June 2012, Manis said. Each jurisdiction within the watershed’s share of the required sediment reduction was calculated separately, and Poway’s share is 320 tons of sediment per year, he added.

The lagoon’s TDML requires all jurisdictions to collectively restore 364 acres of lagoon salt marsh habitat by 2035, Manis said. Another option to fulfill the TDML is demonstrating that sediment reduction measures are affecting 346 acres and will achieve lagoon salt marsh habitat restoration, he added. In general, the lagoon’s salt marsh habitat must have 346 acres restored, Manis said.

Manis said it may be difficult to prove sediment load reductions will restore the lagoon to 346 acres of salt marsh habitat. As such, Poway staff selected the Los Peñasquitos Lagoon Restoration Project to ensure habitat restoration, he added. The project will also ensure compliance with the TMDL, he said.

The project will have multiple phases. Phase One restores the area southwest of the railroad berm within the lagoon and provides guidance for restoration under Phase Two, Manis said. Phase One has three subphases.

Phase 1A includes sediment management and enhancement of the banks along the corridor where Los Peñasquitos Creek and Carroll Canyon Creek converge, he said. It also reduces the upstream flood risk, Manis added. Enhancement of the corridor includes removing non-native vegetation, he said. The subphase also proposes floodplain enhancements to abate sediment flows before they reach the lagoon, Manis said.

Phase 1B focuses on freshwater management, including new channel alignment, side channels and storm drain connections for freshwater, he said. Phase 1C includes 23 acres of nonnative grass conversion to salt marsh native vegetation, he added.

Following the completion of Phase One, Manis said the vegetation and habitat in the salt marsh will be monitored for three years. During this time, plans for Phase Two will be updated with what is learned from Phase One and the observation, he added. Phase Two is anticipated to include additional freshwater management and invasive plant removal in areas north of the railroad berm to Carmel Valley Road, Manis said.

The city of San Diego is the lead agency on the project and is also managing it, Manis said. If Poway should opt to participate, it would be required to cost share with other involved agencies, he added. The current total estimate for Phase One is $35.2 million, Manis said. Poway’s contribution would be 19.65 percent of the total, or $6.73 million, he added. Other involved agencies include the city of Del Mar, San Diego County and Caltrans, he said.

Manis said staff has questioned Poway’s contribution percentage numerous times. He added staff believes the model used to determine it failed to properly incorporate Poway’s sediment reductions done through ongoing channel maintenance within the city. The model identifies Poway as having 615 tons of sediment load annually, Manis said. However, Poway’s channel cleaning program reports the lowest volume of sediment removal in one year as being 196 tons in 2010, he added. Removal volume varies per year, he said.

The project also does not guarantee the reduction of sediment needed to prevent future pollution and water quality exceedances, Manis said.

Manis said the council has three options, including participating in the project for the proposed $6.73 million for Phase One. Other options are declining participation completely and seeking an alternate pathway to compliance, or trying to negotiate with the other agencies about Poway’s contribution percentage, he added.

If the regional board determines Poway is not in compliance with the lagoon TDML by not participating in the restoration project, Poway could be subject to significant fines, Manis said.

The meeting will be closed to the public due to COVID-19. For the complete agenda, go to poway.org. The council meeting can be viewed live at poway.org/ councilmeetings or on TV via Cox Communications Channel 24 and Spectrum Channel 19. Members of the public may speak and participate via poway.org/meeting or by calling (877) 8535247 with meeting ID 623291-9830.

The restoration is part of a joint-agency effort to reduce sediment in the Los Peñasquitos Lagoon.