Desal’s No Savior for Fish

Until the April 5, 2011 City Council study session on the Habitat Conservation Plan (HCP), some City officials claimed that “The City has plenty of water to satisfy current and future water demand in normal rainfall years. Our problem is a shortfall in drought years.” The Water Department’s Habitat Conservation Plan Update revealed that this belief was mistaken. There is not enough water in normal years to satisfy both current water demand and the water flow needs of native fish, let alone future growth in water demand. Even in normal years the City is unable to allow sufficient water flows in streams, defined in the report as “Tier 3 flows”. The report states, “Tier 3 flows…are not currently possible in almost any hydrologic condition due to water supply limitations.”

The Water Department’s report to Council on the HCP focused solely on desalination as a strategy to reduce stream water diversion for human use. But a careful reading of the report reveals that desalination would do little to improve water flows for fish habitat until the plant is expanded in future years.

Desalination would not improve stream flow in normal years in the short and medium term. The HCP report indicates that desalination will not improve fish habitat in the “medium term” (defined as from the time a desal plant is built until 2030) . If the desalination plant is built, it would only raise the number of years that the City can provide Tier 2 water flows to 90%, up from 88% without a desalination plant.

Why no improvement for fish habitat in the medium term? The plan for plant operation has been for Santa Cruz to use the plant for six months during drought years. Thus, stream flows in normal years would not benefit from desalination.

The HCP update indicates that in the “long term” Santa Cruz would use the plant year-in and year-out. If habitat conditions can’t be met in the meantime, Santa Cruz could invoke their priority to use the plant in every year from May through October. Soquel Creek District may find that the Habitat Conservation Plan excludes them from their plan to use the plant during those months (leaving them the use of the plant during the wet season)

Desalination would not increase stream flows in drought years. According to the HCP report, the City will use desalinated water in a drought year to supply customer needs, not increase bypass flows for fish. Even if a desal plant is expanded to Phase III capacity, in nearly half of all years the City would revert to Tier 2 or Tier 1 flows. “In the long-term (beyond the year 2030)…expansion of the water supply project [desal] to 4.5 mgd would allow for Tier 3 flows in 56% of years, but would still require fallback to Tier 2 often and Tier 1 occasionally.”

Compliance with the Habitat Conservation Plan as currently conceived, with its expectation for growth in water demand, would require expansion of the desal plant to Phase II and Phase III before 2030. Such expansions would be necessary just to meet the legally required stream flow commitments.
The Sustainable Solution A solution to improving water flows for fish habitat without building and expanding a desal plant would be to enact a water-neutral growth policy. In such a policy, any new development would pay for conservation methods that fully offset growth in water demand anticipated by the development. Water-neutral growth plus a vigorous conservation effort could continue the downward trend in water consumption of the last ten years. The chart above contrasts such a policy with the current City policy to allow water demand to grow. The water-neutral plus conservation strategy makes 1 billion to 1.5 billion more gallons of water available for fish habitat and drought reserves by 2020.

City faces lawsuit on its claim of adequate water supply

Last August the City Council approved an Environmental Impact Report for the UCSC water service expansion that claimed “There are adequate supplies to serve the project in normal years”. As stated above, the April 5th Habitat Conservation Plan Update indicates that this claim is false, since Tier 3 water flows are unavailable “in almost any hydrologic condition”. The April 5th report confirms the claim of a lawsuit by Habitat and Watershed Caretakers (unaffiliated with Santa Cruz Desal Alternatives) which states, “The project commits the City to providing water that it does not have.” The lawsuit will be heard by Judge Timothy Volkmann on July 20, at 8:30am in Dept 4.

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