In early 2005, state biologists began sharing some alarming new information: The populations of an entire suite of Delta fish species had begun a nose dive three years earlier.

Since one of those fish was protected under endangered species laws, the findings meant Delta pumps surely would be more tightly regulated.

This confronted big water agencies with two basic problems: First, they already knew the channels that convey water to the southern Delta pumps were becoming increasingly unreliable. Second, endangered species laws were now threatening to restrict their access to Delta water.

The solution was to attempt an escape from the strict, extinction-preventing rules of the Endangered Species Act by turning to a more flexible section of the law. The shift would allow water agencies to partially escape tight regulatory oversight, but it also requires them to come up with a detailed "habitat conservation plan" to improve the fate of all sorts of wildlife, including endangered fish.

The success of such plans has been mixed, but in theory they turn efforts away from single species to broader conservation goals. In the process they can provide regulatory stability — in this case, assurances that water supplies will be predictable.

By making the plan's centerpiece a resurrected peripheral canal, the highly controversial aqueduct rejected by voters in 1982, the plan could solve water users' twin problems at once: It would

It would be expensive, and it would be politically difficult. But it got the full backing of Gov. Arnold Schwarzenegger and the agreement of many observers that, given the eye-opening and widespread failures in the Delta, even radical solutions deserved, perhaps demanded, a second look.

Because the developing habitat conservation plan would cover a dynamic and highly degraded estuary that is home to dozens of species, and because of the multitude of demands on the Delta's land and water, the plan appears to be the most complex of its kind ever undertaken.

By 2006, a deal was struck to try to strike a habitat conservation plan deal.

The plan, called the Bay Delta Conservation Plan, is scheduled to be completed by the end of 2010, but key milestones have been missed along the way.

Water users, regulators and environmentalists, for example, were scheduled to have the outline of an all-important key "conservation strategy" by the beginning of this year.

Then it was supposed to be done this week. It is now is supposed to be done by the end of July.

That strategy could include an approach for determining how much water would flow into the canal compared with how much would flow more naturally through the Delta for environmental benefits, details that could help determine how big to make a canal if it is built.

Reach Mike Taugher at 925-943-8257 or mtaugher@bayareanewsgroup.com.