A centerpiece of the problem is the Sacramento-San Joaquin River Delta, the most important estuary on the West Coast. Located just south of Sacramento, the delta sounds far from Southern California but it is the main switching yard for much of the water delivered to cities, businesses and farms in the Southland. Some 25 million Californians receive all or part of their water through the delta.

But experts agree the delta is literally one big storm or earthquake away from disaster. The aging levees that protect the delta are at risk of failing in a major flood or quake, and that would disrupt water deliveries for months or even years.

Such an event would leave Southern California without a major water supply source – with potentially dire consequences for the economy, the environment and the lifestyle that we all take for granted. Climate change, which could usher in longer droughts and more severe floods, is raising even more uncertainty for our water system.

Meanwhile, a crisis involving a troubled delta fish continues to cloud the picture. The State Water Project's delta pumps were shut down for 10 days in June to protect the minnow-sized delta smelt, and further curtailments are likely over the next year.

ETHAN MILLER / Getty Images RECREATION AREA CASUALTY: Nevada's Lake Mead National Recreation Area is experiencing the effects of increased water demand and a seven-year drought.

The system functioned well. But the drought years of the early 1990s, combined with a lack of investment and changing environmental rules, knocked us off the ladder and onto the proverbial chute. The first signs appeared when many local water agencies faced significant cuts in their supplies from the state's two main systems, the State Water Project and the federal Central Valley Project. The cuts stemmed not only from the hydrologic drought, but also from regulatory actions to protect the threatened fish.

The cuts prompted scores of agencies to implement mandatory conservation and rationing. By the time the drought ended, many saw a need for a new approach to water management and more integrated strategies to meet local and regional needs.

Out of this same era emerged the Bay-Delta Accord, a landmark agreement signed in 1994 that sought to end conflict in the delta and resolve key problems. The accord paved the way for the CALFED Bay-Delta Program, which brought state, federal and local agencies and environmental groups together in a united front that translated into significant funding to address the delta and other needs.

The CALFED years represented another ladder for California, one that was sustained for 12 years with investments in programs such as ecosystem restoration, science, water recycling, water-use efficiency, water transfers and integrated regional water management plans. Much of the funding came from statewide bond measures such as Propositions 204 and 13, and matching funds from local and regional water agencies.

Ecosystem restoration received some $2 billion spent over a 12-year period to enhance habitat, remove barriers that blocked migrating salmon and protect fish from diversions along the Sacramento River and key tributaries.

But while the effort can claim many successes, the delta remains in crisis today. CALFED achieved respectable results outside of the delta, but made little progress toward resolving problems within the delta.

So it is that today, despite making progress up the ladder during the CALFED years, we are spiraling down the biggest chute in California water history.

What will it take to get back on a ladder? It will take leadership, action and investment. Simply put, we need bold action on a comprehensive plan to invest in our water infrastructure and address fundamental problems in the delta.

The first step is to recognize that the current delta system doesn't work for people or the environment. That was made clear in a recent report by the Public Policy Institute of California, which concluded the delta is on a “dangerously unsustainable path” with implications for the entire state.

Schwarzenegger and a growing number of legislators have also come to the conclusion that fixing the delta is job one. We must find a way to convey water across the delta that works for water users as well as species such as the delta smelt. And we must do it with a strong commitment to protect the environment and improve water quality.

That comprehensive plan must also include more surface water storage and expanded water conservation programs. Without these investments, it's difficult to see how our water system will function effectively for people and the environment.

It's high time we addressed these issues. Our water infrastructure is in desperate need of investment, and we need swift action to make that investment a reality. Let's not wait for a natural disaster to hammer home the vulnerability of the delta and Southern California's water supply.

Let's make the investments now and get California back on a sustained ladder for generations to come.

Quinn is executive director of the Association of California Water Agencies. ACWA is a statewide association of public agencies whose 450 members are responsible for about 90 percent of the water delivered in California..