FAQ | mpwsp

© 2015 California American Water.

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What is seawater desalination?
A process by which ocean water is turned into fresh drinking water. Seawater is pumped through micro-fibered membranes, which removes salt and other impurities. The membrane is akin to a strainer that blocks out all other material other than water. This and other treatment methods result in a finished product that is devoid of all other materials. In fact. in many cases, minerals and other natural elements must be added back into the desalinated water before it is inserted into the distribution system. 

What happens to the salt?
The brine left over from the desalination process will be discharged back into the ocean at depth. Through the use of diffusers, the brine will be spread out as not to cause any harm to marine life. 

 

 

 

Will we ever run out of ocean water due to desalination?
Not a chance. Ocean water covers more than 75 percent of the earth and in some areas is nearly 7 miles deep. In all, it is estimated that there are more than 321 million cubic miles of ocean water. All the world's rivers, by comparison, make up only an estimated 2,700 cubic miles of water. For this reason, ocean water is considered an unlimited supply of water. Certainly, far more than human activity would ever require.

Is this proven technology?

There are more than 15,000 desalination plants operating throughout the world today. The United States alone has more than 250 desalination plants some of which have been operating for decades. Desalination technology has advanced greatly in the last 15 years and is now exponentially more efficient than earlier generations of plants. In all, desal produces more than 21 billion gallons a day globally, of which more than 300 million people rely upon for their primary water supply.

Is the water quality as good as traditional sources?
The desalination process leaves almost no other elements in the water after filtration. In fact. minerals are often needed to be added back into the water to make it palatable to drink. It will meet or exceed all local, state and federal standards for drinking water. 

If this is such a prime solution, why isn't this done everywhere?
Desalination is only a realistic option for coastal and adjacent inland areas due to their proximity to the ocean.  And although desalination has become much more efficient over the past 20 years, it remains a comparatively expensive option due to the amount electricity needed to power a typical plant. There are also concerns over potential harm to sea life for those facilities that use open-ocean intakes. The Monterey Peninsula Water Supply Project, however, will use subsurface slant wells that don't intrude into the ocean. But rather, they draw from just behind the coastline from a brackish aquifer that consists mostly of seawater. 

How exactly does Desalination work?
Desalination works by drawing water in from the ocean. In this case, we propose subsurface slant wells that will run underneath the ground, eliminating harm to ocean life. The water is pumped up through an array of wells and into a filter tank that removes large debris, brine, sand and bacteria. The water is then pumped into a series of reverse osmosis filters, which removes molecular impurities. The salt or brine that is removed from the water is then pumped back out into the ocean at depth through diffusers that ensure a safe salinity level to avoid harming any ocean life near the outfall. What remains is drinkable water that is then pumped into the system for distribution.  

What is the purpose of the Water Supply Project?
California American Water (Cal-Am) is working toward the completion of the Monterey Peninsula Water Supply Project (MPWSP or “the Project”) to convert ocean water into high quality desalinated potable water in response to state and court-ordered reductions in the community’s primary sources of water, the Carmel River and the Seaside Aquifer. Completion of the Project will restore flows to the Carmel River, providing benefits to endangered species and habitat that depend on the river, and provide the Monterey Peninsula with a reliable, drought-proof water supply. 

What does this Project entail?

The Project will create and expand three water supply sources for the Monterey Peninsula to reduce regional demand on groundwater and the Carmel River. These sources are the desalination facility, aquifer storage and recovery (ASR) wells, and recycled water purchased from the Monterey Regional Water Pollution Control Agency (MRWPCA). The desalination component will include a system of “slant wells” constructed on property owned by CEMEX north of the City of Marina, between the Pacific Ocean (Monterey Bay) and Highway 1. Water pumped from the slant wells will be conveyed by pipe to a desalination plant to be constructed on vacant and disturbed land adjacent to the MRWPCA's Regional Treatment Plant. Cal-Am will deliver water produced at the desalination plant directly to the Monterey Peninsula for municipal uses within Cal-Am’s service area, or to the Seaside Basin for aquifer storage, recovery and subsequent municipal use in Cal-Am’s service area.

 

The Project will also expand Cal-Am’s current ASR project – a partnership with the MRWPCA – which captures excess winter flows from the Carmel River for storage in the Seaside Aquifer and withdrawal during the dry summer months. Winter flows are considered excess only when they exceed what is needed to protect the river’s threatened population of steelhead. Cal-Am plans to construct two additional ASR wells that will increase the capacity of the program and allow the desalination plant to be smaller than would be required without the wells. Finally, the Project expands Cal-Am’s partnership with Pure Water Monterey, a water recycling initiative led by MRWPCA and the Monterey Peninsula Water Management District that will deliver about 3,500 acre-feet of recycled water annually.

So the wells only pump ocean water?
Cal-Am has operated a test well at the CEMEX property in Marina since April 2015. The water drawn from the test well is on average 92 percent ocean water – a percentage that continues to increase with time. The remaining amount is highly brackish (saline) water that is unusable for irrigation or human consumption.

I hear that the Project draws water from below the ocean floor – why is that?
The State Water Resources Control Board, the California Coastal Commission (CCC) and the Monterey Bay National Marine Sanctuary have express policies encouraging the use of subsurface intakes rather than open ocean intakes for desalination projects. This is because underground intakes eliminate harm to ocean life. The test well has shown that subsurface intakes are feasible and therefore Cal-Am must pursue this option in conformance with state law.

Will this Project cause saltwater intrusion?
The Project will actually slow the progress of saltwater intrusion in the Salinas Valley Groundwater Basin (SVGB). The MPWSP will draw seawater and brackish inland water from the western edge of the aquifer which, over time, is expected to facilitate the retreat of the seawater intrusion front. Saltwater intrusion naturally occurs in coastal aquifers due to the hydraulic connection between groundwater and seawater, but intrusion is exacerbated when groundwater withdrawals outpace groundwater recharge. Cal-Am will recharge the basin with a volume of desalinated water equal to the amount of brackish groundwater that is drawn by the Project. Cal-Am will return this water to the SVGB by delivering it to the Castroville Community Services District and the Castroville Seawater Intrusion Project, both of which will use the water in lieu of pumping groundwater from the SVGB. The reduction in groundwater pumping, in turn, will and reduce stress on the groundwater aquifers and help retard saltwater intrusion.

How will the slant wells affect groundwater quality?
All of the water quality and performance data from the test slant well is published weekly at www.watersupplyproject.org. Groundwater quality test results from the well indicate no impact from pumping or non-pumping and the well continues to remain in compliance with CCC permit requirements for the test program.

Who conducted the groundwater model for the Project’s environmental impact report?
The groundwater model developed for the DEIR was created by experts in the study of SVGB hydrogeology. It has been peer reviewed by Lawrence Livermore Labs, among others, tested against historic data, and subject to a superposition analysis – which isolates impacts directly related to the well from external factors – as well as a sensitivity analysis to quantify uncertainty in the model.

Who produced the Project’s Environmental Impact Report?
The California Public Utilities Commission (CPUC) is the lead agency for the California Environmental Quality Act (CEQA) review and permitting of the Project. In 2012, the CPUC engaged an outside consulting team, Environmental Science Associates (ESA) to produce the EIR.  The Monterey Bay National Marine Sanctuary was the lead agency for the National Environmental Policy Act.  

Does California American Water have the legal right to pump water from slant wells in Marina?
In 2013, the State Water Resources Control Board engaged in a ten-month process, including public review and comment, to determine whether Cal-Am could establish adequate water rights to support the Monterey Peninsula Water Supply Project. The final opinion stated that Cal-Am does not require water rights in order to pump ocean water.

The board also found that Cal-Am would have a right to pump brackish water if this action does not harm other pumpers in the basin. The Environmental Impact Report, certified on Sept. 14, 2018, studied the question of harm and found that even under worst-case conditions, Cal-Am’s Project would not harm other pumpers. Cal-Am has appropriative rights to pump brackish water because the Project takes formerly unusable saline water and converts it to water for beneficial public use. This “salvaged” water is “surplus” to the demands and uses of SVGB groundwater pumpers and does not injure the rights of any paramount right holders because the salvaged water is not currently usable, nor was it previously used. Salvaging water to create a surplus that can be appropriated and put to beneficial use is supported by and furthers California water policy.

Won’t the Water Supply Project take water from the Salinas Valley’s groundwater?
92 percent of the water drawn from the test well is ocean water. The remaining amount is highly brackish water that is unusable for irrigation or human consumption. The Project has entered into an agreement with the Castroville Community Services District (CCSD) to return a volume of desalinated water equal to the amount drawn that is determined to be brackish groundwater. Cal-Am will return this water to the SVGB by delivering it to the CCSD and the Castroville Seawater Intrusion Project (CSIP), both of which will use the water in lieu of pumping groundwater from the SVGB. This alleviation of groundwater withdrawals, in turn, provides recharge benefits to groundwater levels in the Basin. Thus, the MPWSP will provide benefits to the SVGB over the life of the project.

Will pumping from the slant wells impact other groundwater supply wells in the area?
The EIR/EIS analysis demonstrates that certain groundwater supply wells located within the slant well area of influence could experience a change in groundwater level between 1 and 5 feet during the life of the project. The “worst-case” groundwater level declines would occur under a 0 percent return water scenario, as in this scenario no water would be returned to the CCSD or CSIP for in-lieu groundwater recharge and pumping in the aquifer would not be reduced. The nearby groundwater production wells that would be affected by the change in groundwater levels have casings, pumps, and screens at depths considerably deeper than those at which MPWSP pumping could affect the water levels. Even in the “worst-case” water level decline scenario, a change between 1-5 feet would not damage or reduce yield in the groundwater supply wells influenced by MPWSP pumping.

Cal-Am recognizes the long-term nature of the proposed Project and the need to provide continued verification that the Project will not contribute to lower groundwater levels in nearby wells within the SVGB. To address this concern, Cal-Am has voluntarily committed to an extensive well monitoring program and will retain an independent hydrogeologist to monitor the water quality and production of existing wells at any well-owners’ request throughout the life of the Project. If it is determined that a nearby active groundwater well has been damaged or otherwise negatively affected by the Project pumping of the slant wells, Cal-Am will coordinate with the well owner to arrange for an interim water supply and begin developing a mutually agreed upon course of action to repair or deepen the existing well, restore groundwater yield by improving well efficiency, provide long-term replacement of water supply, or construct a new well.

Does the MPWSP violate Section 21 of the Monterey County Water Resources Agency Act?
The Project is consistent with Section 21 of the Agency Act. Section 21 of the Agency Act prohibits the export of SVGB groundwater from the Basin and authorizes the Monterey County Water Resources Agency to seek an injunction against violators of this rule. This statute is not applicable to the MPWSP because the Project returns a volume of water to the SVGB equal to the percentage of groundwater it withdraws so that no “export” occurs.