A new report issued by the California Environmental Protection Agency (CalEPA) shows that at least half of California’s landfillbound food waste could be processed at the state’s wastewater treatment plants and serve as an innovative power source while reducing greenhouse gases. 

Waste can be “co-digested” at these facilities, which involves adding organic wastes including municipal food scraps and industrial food processing wastes to a facility’s anaerobic digester. Through a survey of nearly 225 wastewater treatment plants in California, the report finds that many have existing anaerobic digestion capacity to accommodate diverted food waste. While maximizing the use of that excess capacity would require additional infrastructure investments, the report shows such investments would benefit California’s economy while advancing environmental goals.

The report estimates that:

  • Statewide capital investments required to use the co-digestion capacity range between $900 million and $1.4 billion, while the net benefits to the state could be up to $255 million each year.
  • Maximizing co-digestion capacity at wastewater treatment plants could reduce statewide greenhouse gas emissions by as much as 2.4 million metric tons of CO2- equivalent per year. That’s more than half of the emissions from landfills that California committed to reducing by 2030.

California’s State Water Resources Control Board has officially resolved that its response to climate change “must be comprehensive and integrated into all Water Boards’ actions,” and State Water Boards have taken a variety of such actions, including expanding recycled water to increase drought resilience and adopting regulations to increase the collection of urban storm water. Water Boards are continually seeking out projects that not only increase the resilience of water supplies and of ecosystems, but also have the potential to reduce greenhouse gas emissions.

State Water Board Chair E. Joaquin Esquivel said “the (CalEPA) report’s findings are very promising. It shows California’s wastewater treatment plants have the existing anaerobic digestion capacity to accommodate at least half of California’s landfilled food waste—likely more. We look forward to working with our industry partners to get more of these projects off the ground.” 


Water Blogged – A Regional Projects Overview

The following data offers a quick overview of proposed and ongoing water projects regionally in Southern California.


Los Angeles – The $20 million Los Cerritos Channel Project in south Long Beach will collect water from streets, parking lots and other surfaces in Long Beach and Signal Hill, funneling the liquid into a cistern where it will be treated to be reused for drinking and other household purposes

The Los Angeles County Department of Public Works resumed work on an essential infrastructure project at Devil’s Gate Reservoir in the City of Pasadena. The Devil’s Gate Reservoir Restoration Project is a four-year effort to increase vital flood protection for communities downstream of Devil’s Gate Dam.

The River Supply Conduit 7 (RSC7) Project in Burbank replacing pipes that were installed in the 1940s and are approaching the end of their typical lifespan is expected to be completed by April 2022.


Orange County – Projects include the construction of the Groundwater Replenishment System (GWRS) Final Expansion Project. The GWRS provides the region with water it can count on instead of importing water from distant watersheds.

The project is expected to be complete in 2023 and takes highly-treated wastewater that would have previously been discharged into the Pacific Ocean and purifies it using a three-step advanced treatment process, resulting in high-quality water that meets or exceeds all state and federal drinking water standards. Upon completion, the world’s largest water reuse project of its kind will produce 130 MGD of advanced purified recycled water


Riverside County – The La Sierra Pipeline is an ambitious capital improvement project in the works since 2017. It aims to provide safe and reliable locally-sourced, drought-resistant drinking water to the region. As part of its final phase, it will connect to the Sterling Pump Station and Arlington Desalter allowing water to be pumped and delivered to approximately 80,000 customers.

Catching the rain that does fall on the county, is reused via the Enhanced Stormwater Capture and Recharge Project (Recharge Project) on the Santa Ana River near the Seven Oaks Dam. Rather than losing water to evaporation and runoff, the Recharge Project uses Santa Ana River water to replenish sedimentation basins capable of handling 500 cubic feet per second. Those waters then seep into groundwater basins that are later pumped and conveyed to local water agencies. Riverside County extracts its water from three groundwater basins: Bunker Hill Basin in San Bernardino, Rialto Colton Basin in Colton, and the Riverside Basin. These are usually filled by rain and snowmelt, but at a slower pace due to drought conditions. With the Recharge Project and other conservation efforts, annual analysis of groundwater levels by local water agencies shows significant increases over the past 10 years throughout most of the Coachella Valley

In the City of Riverside, projects such as the Jackson Street Recycled Water Pipeline Project will add approximately 26,000 linear feet of 8-inch and 24-inch diameter pipeline to provide an estimated 821 acre foot a year (AFY) of recycled water to existing and future customers along its path. The project improves water supply by reducing the amount of water discharged into the Santa Ana River.

Ventura County – In addition to drought, a growing population also provides a challenge for meeting water demands . the Ventura WaterPure and State Water Interconnection Projects will help diversify sources. The Advanced Water Purification Facility project is slated to produce up to 4,000 acre-feet of recycled water per year. Tapping into state water via a 7-mile pipeline near Camarillo will serve as a backup if or when water levels get troublingly low. 

While drinking water is essential, a healthy water supply is also important for many other components of the Ventura County community. Constructed in 1948, the Matilija Dam on Matilija Creek was created to store water for agriculture and to provide flood protection. Over the years, it also trapped sediment that was vital to the downstream habitat, including spawning steelhead trout. 

The Matilija Dam Ecosystem Restoration Project (MDERP) enhances 33.6 miles and 2,268 acres of instream and riparian habitat along the Ventura River and its tributaries. The dam removal allows for a natural flow of sediment to replenish downstream river sections and coastal beaches.