Tuesday, May 20, 2008 | For the first time, the city of San Diego is requiring a developer of a large project to offset its water demand, a step designed to address concerns that new development will exacerbate the city’s strained water supply.

The city’s Water Department is requiring Westfield, the developers of the $900 million University Towne Center mall expansion, to keep the project’s water demand neutral, a step that will require the developer to save between 21 million and 43 million gallons of water annually.

In the UTC project, new stores and residences will use more water, which the developers will offset by using reclaimed water — non-drinkable treated sewage — for irrigation. The company will also pay for other existing developments to do the same, enabling those using drinking water for irrigation to switch to reclaimed, non-potable water. That would boost the amount of drinking water in the city’s system, neutralizing the expansion’s increased demand.

For now, the policy is informal, hasn’t received City Council support and has no violation penalty.

“This is all relatively new stuff, and it’s clearly being driven by an increased awareness of what the water supply conditions for Southern California are,” said Jim Barrett, the city’s director of public utilities. “I think we’re taking a much more proactive approach than we have in the past.”

Barrett said he looks to offsets as a way to address a state law requiring an assessment of large developments’ water supplies. The 6-year-old law, designed to ensure that supplies keep pace with growth, mandates that cities provide what is termed a “water supply assessment” for large developments: Subdivisions with more than 500 homes, hotels with more than 500 rooms, offices serving 1,000 or more people or shopping centers with more than a half-million square feet. The assessment must verify the city has a sufficient supply planned to accommodate the growth.

Most projects in the city would not rise to that level. Few are large enough to trigger the assessment. A Westfield spokeswoman declined comment.

The world of water once looked starkly different than it does today, when climate change was an uncertain concept that hadn’t gained widespread acceptance and the Sacramento-San Joaquin River Delta appeared to be a nearly limitless supply of water for San Diego.

But the West is warming, mountainous snow packs that store vital supplies of water for Southern California are shrinking, and a federal judge has limited water exports from the delta in order to protect the delta smelt, a tiny endangered fish.

As a result, the city is taking steps to make sure that the water demand it expects in 2030 stays level. By then, the city plans to annually use about 20 percent more water than it does today. That increase is the result of models that project water consumption for parcels across the city. If a large project exceeds its planned allocation, Barrett said the city will require it to offset, or neutralize, the excess, as is the case with Westfield.

Offsets are commonly used in environmental mitigation, but are new to the local world of water. Developments that impact threatened habitat are required to protect similar ecosystems offsite. The practice of carbon offsets has similarly gained acceptance as a cost-effective — though largely unregulated and unverifiable — way to reduce the emissions of greenhouse gases that cause climate change. Several websites allow people to calculate how much carbon dioxide they emit and offer to take payment to plant trees, a step that reduces atmospheric carbon.

“The concept of offsets is getting traction … because you’re adding demand in the middle of a crisis,” said Ken Weinberg, the San Diego County Water Authority’s director of water resources. “One way to address that is to not add demand. That solves the problem because you’re not relying on a supply that’s not there to address demand that is.”

The city has generally held demand steady since 1990, despite adding 200,000 residents. The city’s population increased 18 percent; water consumption increased 2 percent, the result of an array of conservation initiatives such as the installation of low-flow showerheads in homes across the city.

The concept of water neutrality to address future demand is not chaptered anywhere in the city’s policies. Barrett said he is exploring the idea of water-neutral development on a case-by-case basis and would eventually make a proposal to City Council.

“We’re not at the point where we’ve worked out the details,” he said. “We’re sort of flying by the seat of our pants.”

City Attorney Mike Aguirre has criticized the city’s past reviews of water supplies for large developments, saying the process had amounted to little more than a rubber stamp. He dismissed offsets as a marginal contribution.

“Offsets tend to be more fiction than fact,” he said. “Offsets are difficult to monitor and police and usually go by the wayside.”

Aguirre questioned whether the city has accurately accounted for its long-term water supplies. The city’s plan was created in 2005 and includes no mention of the potential impacts of climate change or the delta’s uncertainty. It will not be updated until 2010.

San Diego County households narrowly dodged mandatory rationing this year, the result of an average winter’s snowfall in the Sierra Nevada. With the threat of rationing water continuing to loom, Aguirre said the region should not increase its demand for water.

“What’s the point of having the 20-Gallon Challenge, asking some people to give up 20 gallons when you’re asking more people to come in and use more?” Aguirre asked, referring to the water authority’s conservation push.

While water assessments can be hard to prove, said Craig Benedetto, a spokesman for several developers, supply strains can be addressed by focusing on creating local supplies like recycled water.

“It’s like proving electricity is going to be there,” Benedetto said of the assessments. “It’s still a subjective conclusion. The other option if you don’t believe the forecasts is to stop all development. So do you kill the economy or think about water reuse?”

In the future, the smelt decision and any impacts from climate change will hurt San Diegans less than today, Weinberg said, because the authority, which provides the city with most of its water, has long planned to reduce its reliance on imported water from the delta and Colorado River. Local supplies planned such as desalinated seawater or recycled sewage will reduce dependence on imports.

“Over time, that portion at risk is a smaller part of our portfolio,” he said. “The difficulty now is that people are looking for answers and there aren’t any yet.”

While the state debates potential answers to the delta’s problems, such as a canal around the delta’s periphery, offsets are likely to continue to attract attention, Weinberg said.

“It’s a time of uncertainty right now because of the delta,” he said. “It’s what’s driving the train toward offsets as an approach for now — until we figure out these other problems.”

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