Do Fish Need Desal?

coho swimming upstream to spawn

The Santa Cruz Weekly published a cover story reporting that the National Marine Fisheries Service (NOAA Fisheries) supports the desal plant in Santa Cruz. Sadly, the agency charged with protecting endangered fish currently supports desalination, despite the fact that the CO2 from the plant’s electric power consumption will contribute to the acidification of the ocean, causing potentially catastrophic harm to fish species.

NOAA Fisheries means well. They want the San Lorenzo River to support coho salmon once more, and to increase populations of steelhead salmon to historic levels. In order to restore native fish habitat, water agencies and private water users in our watershed need to cut back on diversion of water from streams. Scroll down to read about the water flow needs of native fish.

The sad irony is that the City of Santa Cruz has never agreed to NOAA Fisheries requests to link the output of the desalination plant to the needs of endangered native fish. In a 2005 comment on the City’s Draft EIR for the Integrated Water Plan, NOAA Fisheries made this request,

“The City has not linked the proposed desalination project to their proposed Habitat Conservation Plan. We believe linking these efforts is essential to address the City’s ongoing takings issue.” [takings means reducing the population of endangered species]

In the EIR, the City responded to this request,

“NOAA Fisheries is suggesting that the City is responsible, through the Integrated Water Plan (IWP), for remedying prior impacts on endangered species in areas that are not related to the Proposed Program. The City has no such obligation as part of the IWP.”

In other words, the City wants to build a desal plant, but doesn’t want to be required to use it to allow greater water flows in the streams.

Santa Cruz Desal Alternatives is in dialogue with NOAA Fisheries, bringing to their attention the strategy of water transfers between districts— a solution that could be designed to remedy drought, aquifer overdraft and fish habitat. In our correspondence with NOAA Fisheries, we make the point that no amount of conservation—or new water supplies—will protect the fish unless there are controls that prevent water demand from rising. Soquel Creek District already has a program that offsets growth in water demand from new development by replacing plumbing fixtures in existing development. Santa Cruz has yet to make water-neutral development their city policy. A LAFCO decision requiring UCSC growth to be water-neutral would be an important contribution to fish habitat, since otherwise City water demand will grow by 120 million gallons/year.

In the SC Weekly article, NOAA Fisheries states that the alternatives to desal “won’t happen quickly enough to help the fish”. It’s important to note that conservation is of immediate benefit to fish habitat. Conservation has already allowed the City to release greater amounts of water in local streams. Our water demand has declined from its peak of 4.2 billion gallons per year to 3.6 billion gallons per year in 2008. Although the numbers are not available yet from 2009 and 2010, it appears that water demand in the last two years was close to 3.1 billion gallons. What this means is that there are 600 to 1100 million gallons of water available for fish habitat that was diverted from streams when the City was at its peak use. Conservation is far superior strategy to desalination as a strategy for fish habitat, since conservation can increase the amount of water available for fish habitat every year, rather than the one in six years that the City plans to use the desal plant.

Given sufficient political will from the City Council and Soquel Creek Board of Directors, water exchanges between districts could happen sooner rather than later. The State of California encourages such transfers for the very purpose of habitat conservation.

In 2002, NOAA Fisheries initiated legal action against the City for "take" of endangered species at Laguna Creek.

Water Flow Needs of Native Fish

a summary of Save Some Water for the Fish, a 21 minute video with Don Alley, fisheries biologist


The section of the San Lorenzo River between the Henry Cowell Big Trees and Paradise Park is known as the Gorge. Some sections are filled with boulders which are potential barriers to fish that are returning to spawn. In these boulder areas the fish need a minimum of 50-70 cubic feet per second of water flow in order to navigate passage.1 Upstream of the Gorge is the City’s Felton Diversion. The City inflates a dam during drought years to allow water pumping to Loch Lomond, when the lake is not expected to fill through normal runoff into Newell Creek. State water rights mandate a minimum bypass flow of 25 cubic feet per second at the dam. This is half or less of what the fish need for passage up the Gorge. Reports from the 1977 drought year describe hundreds of returning salmon stranded in the Gorge.2

“Smolts” are young fish that have undergone the physical change that allows them to survive in salt water. Coho and steelhead salmon molts migrate to the ocean in March through May. They need enough water flow in the river to allow passage downriver to the ocean. During drought years the river has dried up below the City’s main water diversion just above Highway 1. There are no minimum bypass flow requirements at the City’s main water diversion, since the water rights there pre-date public concern for fish habitat.
During low flow periods in the river, the ocean waves create a sandbar at the mouth of the river. This is a normal occurrence in the summers. If the sandbar closes prematurely, smolts cannot outmigrate.

Summer flows in the tributaries and mainstem of the San Lorenzo River are important for the growth of juvenile salmonids that have not reached the smolt stage. Salmonids can take up to two years to become smolts. They need sufficient water flow for adequate water depth, cool temperature, and a rapid flow of passing insects. Summer flow (base flow) in Bean Creek and Zayante Creek is affected by groundwater pumping of the Santa Margarita Aquifer by Scotts Valley Water District and San Lorenzo Water District.3 A significant amount of water is diverted from Fall Creek, Boulder Creek and Clear Creek by the San Lorenzo Valley Water District and Lompico Creek by the Lompico Water District.

1 Swanson Hydrology & D.W. Alley, San Lorenzo River Salmonid Enhancement Plan, (2004) p. ES-10
2 Don Alley, Fisheries Biologist, Transition Santa Cruz video, Save Some Water for the Fish
3 Swanson & Alley (2004) p ES-11

One Response to Do Fish Need Desal?

  1. Jude Todd says:

    Great point: fossil fuels –> C02 –> ocean acidification –> dead fish. And PG&E gets half its electricity from fossil fuels. Another 13% comes from hydroelectric, which, due to associated methane production, is 3 times more polluting than coal or oil fired power plants. So the majority of energy used to run a desal plant would be polluting the air and then the water, destroying more fish. Using desal to save water to spare local fish would therefore mean harming fish elsewhere. Much better to just conserve the water in the first place and spare fish both here and in the oceans.

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