Desalination & The Monterey Coast

There are a number of options for boosting future water supply. Marina Coast Water District (MCWD) supports innovation and technology to develop new supplies, and that could someday include desalination. The key is that these projects must be done responsibly, with careful consideration and scientifically sound data. They must be evaluated based on the potential impact to the ecosystem, ratepayers, and groundwater supply. As this piece in the San Francisco Chronicle points out, Cal Am’s proposed desalination plant would ignore state environmental protections, deplete scarce water resources, and cause further seawater intrusion into the aquifers.

Known as the Monterey Peninsula Water Supply Project, the Cal Am desalination plant raises numerous concerns for MCWD. The plant will not provide any benefits for MCWD customers, yet it will have a significant impact on their groundwater and the local community. Cal Am plans to build intake wells in Marina – leading to construction impacts – and these wells will not draw from the ocean, but will draw from Marina’s aquifers and pull seawater into the groundwater basin. The damage to the basins and water supplies should have been evaluated in Cal Am’s Draft Environmental Impact Report (DEIR) as part of the approval process with the California Public Utilities Commission (PUC). However, the DEIR fails to evaluate the plant’s impacts using the best available information and science, which led MCWD to submit extensive comments to the PUC on the inadequacies of the CalAm report. The proposed plant would also violate California’s Sustainable Groundwater Management Act passed in 2014, which protects 21 of the state’s critically over-drafted basins.

Recently, MCWD commissioned a research project led by Professor Rosemary Knight, Ph.D, of Stanford University’s School of Earth, Energy & Environmental Sciences. The study confirmed that sources of drinking water exist in the basins where the proposed plant has located intake wells which provides a barrier to seawater intrusion. This was also documented in other recently completed technical studies from hydrogeologist that studied the area This source of drinking water can be compromised by this project – a scientific fact that is overlooked in Cal Am’s DEIR. The most alarming data was gathered from the test intake well for the proposed plant, which clearly shows it is drawing from MCWD’s groundwater and pulling seawater into the area where the source of drinking water exists. This is not addressed in the DEIR and neither is mitigation for Marina. The plant will significantly reduce groundwater supplies and water quality in the Marina area, yet the mitigation plan is to return the groundwater it pumps from Marina’s aquifers to Castroville. Returning groundwater north of Salinas River will not mitigate the seawater intrusion caused by pumping of groundwater in the Marina area and the seawater intrusion caused by the project will prevent future groundwater recharge projects to be implemented, projects that are currently being developed as part of MCWD’s Groundwater Sustainability Plan.

Concerns have also been raised about the size of the proposed plant, which would generate double the amount of water that is needed. Cal Am would have a total water supply of more than 17,000 acre-feet per year.  In 2016, Cal Am’s customers used 9,285 acre-feet per year. This project will cost current ratepayers in legal fees, and potential damage to local water supply.

Along with many others, MCWD has called for a new DEIR to present a scientifically sound evaluation of the plant’s impacts. MCWD remains committed to an open dialogue as the plant is reviewed, in an effort to move forward with a solution that represents wise public policy. Cal Am is encouraged to join this dialogue, to pursue a project that won’t compromise an already over-drafted groundwater basin and cause harm to the community. There are a number of reasonable, realistic and far less expensive alternatives to augment regional water supply than building a massive desalination plant.