It's been more than a quarter of a century since California last made any significant changes to the core of its water system in the Sacramento-San Joaquin Delta. But now the political window appears to be opening to find historic and lasting solutions within the Delta.

When it comes to reviving and repairing the state's most important estuary and the heart of its water supply system, it isn't surprising that views tend to vary. Yet the importance of the Delta to the state's environment and economy is creating powerful motivators to find a solution.

As legislators in the coming months get further into the Delta issues, they will find something remarkable and historic among key leaders in the water community. There's now a broad, expanding consensus on the various elements of a Delta solution, including the need to physically isolate a recovering ecosystem from the movement of water supplies to two-thirds of California's population. Yes, that means some form of a canal.

The bottom line is that it isn't enough to improve the Delta's outdated water system or to restore portions of the ecosystem. There must be a plan that addresses all the Delta's fundamental problems while honoring the water rights of Northern Californians, the needs of agriculture and the 25 million people who depend upon these water supplies. The key, in a word, is comprehensive.

The estuary suffers from numerous wounds – invasive species, a collapse of the aquatic food web, pollutant discharges and the inevitable problems of trying to move large quantities of fresh water through a tidal estuary. Key fish species are at record low populations. New lawsuits and new water supply restrictions are narrowing the opportunities to move water supplies across the Delta from the Sacramento River to the pumps of the State Water Project and Central Valley Project. The ability of the state's water system to capture water reserves in wet years, in order to survive the dry years, has been all but shattered.

Some extraordinary work by the University of California, Davis, the Public Policy Institute of California and Gov. Arnold Schwarzenegger's Delta Vision Blue Ribbon Task Force has elevated the understanding of the Delta's problems. Better science and provocative ideas have led to common ground and goodwill to work on those important details.

A Delta canal is vital because it will restore the water system's ability to reliably transfer water captured in wet periods for use in dry ones. It will dramatically reduce the loss of fish from the effects of pumping. The key is to protect both wildlife and the water supplies for our farms and cities.

Improving flood management is critical. So is reducing the population of non-native predatory species that consume threatened fish such as salmon and smelt, and expanding water conservation statewide. Studies for new surface and groundwater storage proposals must be completed, such as a proposed Sites Reservoir in the Sacramento Valley, so that all ideas get a full and fair evaluation.

For Northern California, a key assurance is to solve problems within the existing system of water rights. This system recognizes the seniority of water rights as well as the areas where the water comes from.

As for financing, those who benefit from a new project should pay. The public water agencies that would be supplied by a new Delta canal are on record as prepared to pay for this new conveyance facility out of their pockets, not those of all state taxpayers. The California Legislature will play a crucial role in finding the funds to underwrite the broad public benefits of restoring the ecosystem.

Undoubtedly there will be different perspectives among water leaders and other key stakeholders along the way. But we are farther along on this journey than many may realize. It's time to see this journey to a successful end so that water policy in California can enjoy a new beginning.

Donn Zea is president and chief executive officer of the Northern California Water Association. Jeffrey Kightlinger is general manager of the Metropolitan Water District of Southern California.