Helping Provide a Clean, Safe, and Sustainable Supply of Water 

To support a fair and equitable project for the region that improves access for disadvantaged communities and makes them more climate change resilient, we are proposing returning a portion of our product water to help provide additional source water to the Castroville Seawater Intrusion Project, but more importantly, providing a new source of potable water to the City of Castroville.  

For additional information on this portion of the project, the information contained below is drawn directly from the Environmental Impact Report.

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MPWSP source water would include some brackish groundwater from the SVGB. As part of the 
proposed project, CalAm would return to the SVGB a volume of desalinated product water equal 
to the amount of SVGB groundwater included in the source water. While CalAm’s SVGB return water obligation will be based on the amount of fresh water in the source water, in order to consider the effect of the return water for this EIR/EIS, groundwater modeling simulated scenarios with return water obligations representing 0, 3, 6, and 12 percent of the source water (see Section 4.4, Groundwater Resources). The amount of SVGB groundwater included in the source water is expected to decrease over time (CalAm et al., 2016b). 

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In June 2016, several parties involved in the current proceeding asked the CPUC to approve their proposed “Settlement Agreement on MPWSP Desalination Plant Return Water” (CalAm et al., 2016b). The settlement describes how CalAm would fulfill its annual SVGB return water 
obligation. As the settlement explains:

Water Demand, Supplies, and Water Rights

• Delivering return water by injecting desalinated water from the proposed project into the SVGB is considered less desirable than delivering return water for beneficial use in the SVGB
   

• The Castroville Seawater Intrusion Project (CSIP) may not have sufficient capacity to accommodate all of the MPWSP SVGB return water under some conditions. 
   

• The Castroville Community Services District (CCSD), which provides municipal and domestic water service to the Town of Castroville, currently relies on about 780 afy of SVGB groundwater to meet Castroville’s water demands, and increasingly has experienced water supply challenges because the water is getting saltier.
   

• The CCSD wants to take delivery of a SVGB return water supply to replace all or part of CCSD’s current reliance on groundwater from the SVGB.

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To fulfill its SVGB return water obligation, CalAm would make return water available for other water suppliers to use instead of pumping groundwater from the SVGB. The return water settlement requires CalAm either to make 800 afy of return water available for delivery to CCSD, assuming they build the 9.6 mgd plant, or to make 690 afy available if they build the 6.4 mgd plant. CCSD’s avoided cost – that is, what they would have had to pay to produce enough groundwater to meet demand – will determine the price that CCSD would pay for the return water. If there is any return water left after CCSD takes its share, CalAm would deliver it to the CSIP.