Some things never change.

The vitality of the single most important estuary on the West Coast is once again at risk from an old-fashioned political power play. If it's successful, local water users, the economy and the environment of our region and state will pay a huge price.

The San Francisco Bay-Delta, at the confluence of the Sacramento and San Joaquin rivers, is the centerpiece of a complex ecosystem on which critical wildlife and fisheries depend, and on which our regional and state economy rely heavily. When the Delta suffers, we all lose: an ailing Bay-Delta means declining fish populations, lost jobs for fishermen and their small business suppliers, harm to Delta farmers and increased risk to fresh water supplies.

It isn't news that the Bay-Delta faces multiple threats – from levee instability, climate change, invasive species and over-pumping to water users to the south, to name just a few.

And while it is true that many previous efforts to address these threats have failed, we believe that a credible and balanced long-term plan to restore this important natural resource is still possible.

However, plans to save the Bay-Delta now face a greater threat: the water grab currently under way. State and federal leaders must respond to this new threat swiftly and decisively if we are to make progress in saving this vital water resource.

The multi-party planning process known as the Bay Delta Conservation Plan, or BDCP, has been struggling for several years. That program is currently contemplating the construction of two 40-mile tunnels to allow even more water from this damaged ecosystem to be diverted out of the Delta. But throughout this BDCP planning process, fishermen, the five Delta counties, and local communities and interests have been left out. We've heard from many of our constituents that their input is ignored while key decisions are made without them.

Environmentalists have been stalled in making progress toward their goal of establishing adequate water flows to a healthy Delta. And state and federal scientists – including at the National Academy of Sciences – have repeatedly questioned the plan's scientific rigor.

Simply put, the Bay Delta Conservation Plan is on course to fail.

And if it fails, it will be because a few powerful Central Valley and Southern California water contractors were given overwhelming and unfair advantages, including through a recently signed agreement with the state and federal government granting them unprecedented influence over this important public process.

What advantages do they have? Water contractors can select the consultants writing the BDCP documents, can stop key documents from being finalized unless their demands are met and can hold scientists to an unrealistic timeline that would rush many important decisions and evaluations.

And when local Delta agencies write to state and federal agencies with concerns about the plan, this agreement gives the water utilities in Los Angeles and Fresno a role in drafting the government's responses. That is unacceptable.

Yet this agreement doesn't require the water export contractors to explain how they will mitigate the impacts of the enormous infrastructure project they seek, despite legal requirements that the beneficiaries of the project must issue a plan to pay for that mitigation.

We agree that those who rely on Delta water exports deserve a plan that reduces risks to the Delta and the water supply it represents. But we strongly disagree that their interests trump those of the other stakeholders around the state, like fisherman, local farmers, local water agencies and surrounding communities.

As long as this agreement and the imbalances it represents are in effect, the Bay Delta Conservation Plan will be remembered as just the latest in a series of attempted water grabs by powerful agribusinesses and water agencies – the same type of behavior that helped drive us into this mess in the first place.

Officials in Sacramento and Washington have given too much power to the water contractors. But there's still a chance to change course. After we publicly criticized the flaws in the agreement, state and federal officials wisely offered the public an opportunity to submit comments. We've submitted letters detailing our concerns and recommendations, and so have grass-roots environmental groups, the Delta counties, several regional water agencies, fishing groups from up and down the West Coast, and many others.

Our friends in the Brown and Obama administrations must seriously – and immediately – address these criticisms and suggestions so they can lead this effort in a more productive and successful direction. Only by taking back the reins and rebalancing the process will they be able to protect the public interest and restore trust in the Bay Delta Conservation Plan.

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Rep. George Miller is a Democrat who represents much of the Delta. Rep. Doris Matsui is a Democrat who represents Sacramento. Also signing this opinion piece are U.S. Reps. Mike Thompson, D-St. Helena; Jerry McNerney, D-Pleasanton; and John Garamendi, D-Walnut Grove.