A delta tunnel project's lofty ambitions have been scaled back

A dog trotted down the middle of a levee road as red-winged blackbirds darted in and out of the reeds. A few fishermen dangled their baited lines into the muddy brown water.

Only a close look at the Middle River revealed anything amiss in this part of the Sacramento-San Joaquin Delta. Instead of flowing north toward San Francisco Bay, as nature intended, the Middle was headed south. On the other side of Bacon Island, the Old River was doing the same thing.

The backward flow of these two obscure channels is at the core of a proposal to build California's biggest water project in decades: a $15-billion diversion and tunnel system in the delta, the ecologically failing hub of the state's waterworks.

The long-planned project would draw directly from the Sacramento River as it enters the north delta and send water to enormous pumping plants that now pull supplies entirely from the south delta. The intensive pumping that now takes place causes the environmentally harmful reverse flows that have triggered increasingly tight limits on water deliveries to San Joaquin Valley growers and Southern California cities.

In news releases and tweets, tunnel backers have lamented the "lost" and "wasted" water from the Sacramento River that could have been pumped south during this year's winter storms if only the delta had a "modern delivery system." About 486,000 acre-feet — or enough water to serve 3.6 million people for a year — could have been captured, the project website proclaims in big, bold numbers.

To read the full article go to www.latimes.com