A team of researchers with impeccable credentials and unquestionable independence is uttering an inconvenient truth that California and its politicians have ignored for much too long – a peripheral canal is the least expensive, most environmentally positive way to repair the Sacramento-San Joaquin Delta while maintaining vital water supplies.

The Public Policy Institute of California (PPIC) assembled the team and released its 184-page report on Thursday, quite likely the most important paper PPIC has published in its 14-year history of foundation-supported research.

A peripheral canal, which would carry Sacramento River water around the Delta to the head of the California Aqueduct near Tracy, was part of the California Water Plan endorsed by voters in 1960.

After the Legislature finally approved a canal in the early 1980s, however, an odd-bedfellows alliance of San Joaquin Valley farmers and environmental groups challenged it via referendum. After a very misleading campaign, voters rejected it in 1982.

Ever since, politicians have shied away from a peripheral canal – or the "P-Word," as many in water circles call it – because of its controversial image, even though many water engineers and environmental researchers privately agree with what the PPIC report says publicly.

Pulling water from the Delta interferes with natural flows and degrades water quality, thereby damaging wildlife habitat. While stopping exports would, perhaps, solve that problem, it would deprive California of its largest source of water.

As PPIC says, the problem will grow more acute if global warming, as expected, raises sea levels, thus putting many Delta agricultural islands in danger of reverting to marshland and making its waters saltier. Meanwhile, a major earthquake could make that happen suddenly as it liquefies Delta levees.

With the courts severely restricting water exports from the Delta because of declining fish populations, there has been renewed interest in a peripheral canal, although that term is largely banned from official discourse. But fierce opposition persists, mostly from Delta farmers concerned that a canal would isolate them from public money to fix their deteriorating levees (although they rarely admit to that motive) and from environmental groups that want to use restricted water supply as a tool to curb development in Southern California (although they are equally reluctant to admit that).

Environmental groups once supported a peripheral canal as the best Delta fix, but pulled off. While shedding public tears over the Delta's plight, they have been, in effect, willing to sacrifice its environmental health for their other agenda.

Many years and countless billions of dollars and human-hours of meetings and studies have been squandered in a vain search for a consensus that does not include a peripheral canal. The PPIC team concludes that it's time to end that charade and do what's been needed for decades.

"To be viable," the PPIC team said, "a long-term solution must include governance, regulatory and financial arrangements to ensure that various goals are well served, including water supply, environmental management, and the state's local interests in the Delta. It is unlikely that local and regional stakeholders can negotiate such arrangements on their own in a timely way, given the complexity of the problem and its innumerable stakeholders. Pursuit of a grand consensus solution for the Delta's many issues is likely only to continue the deteriorating status quo."

The PPIC report is unlikely to sway a peripheral canal's opponents, but their agendas pale next to the larger public interest in improving the Delta's ecology and assuring the state of a reliable water supply. It's time for that larger interest to assert itself.

Call The Bee's Dan Walters, (916) 321-1195. Back columns, www.sacbee.com/walters.