A kayaker makes his way along the Kalamazoo River toward Interstate 94 near Marshall, Mich., on May 7. There  has been an ongoing cleanup of the river since an oil spill in 2010. (Elizabeth Conley/Detroit News via AP)

Last week, the Obama administration released a new regulation defining the scope of “waters of the United States” for the purposes of the Clean Water Act (CWA). The rule will clarify which streams and wetlands have enough connection to the nation’s navigable water bodies that they are subject to the law’s protections.

Political backlash has been intense: Industry and farm groups are campaigning vigorously against it, and legislation to block it has passed the House and is moving through the Senate.

That opposition is hardly surprising. Businesses and landowners will now need to acquire permits to pollute or alter these streams and wetlands — and some of the most harmful activities may be prevented entirely.

But the new rule will do something else that may — or may not — get a reaction: Reassert federal agency authority and impose consistent nationwide environmental standards. That counters a multi-year trend that has dispersed environmental oversight to local and state governments and established more state-specific standards. And so far, states aren’t putting up the fight we might have expected.

States often resist expanded federal authority. This time, however, the Environmental Protection Agency and the Army Corps of Engineers are offering to help protect states against the harm they do to one another’s waters. So instead of fighting the federal government, states instead may welcome federal assistance in defending against their neighbors.

Water, water everywhere

Right now, hundreds of federal, state and interstate agencies share oversight of our surface water. That means water quality protections vary dramatically from place to place. Some states require careful review before there’s any dumping or construction in streams and wetlands. Others neglect local water quality, even prohibiting state agencies from protecting waters more rigorously than required by federal law. That’s because, like several other major environmental statutes, the CWA establishes minimum levels of protection nationwide, allowing states to set and enforce their own standards.

But just as not all states’ standards are equal, their actual oversight varies as well. Many states don’t have the money or staff to carry out the CWA’s mandates: issuing permits, tracking compliance and imposing penalties. Courts have become ever more involved, reviewing permitting and enforcement decisions case by case. State and district courts were issuing idiosyncratic judgments, often politically motivated. One study showed that political composition of the district courts even preemptively influenced Army Corps permitting decisions. As a result, polluters have often been able to discharge dangerous waste into water bodies without punishment, jeopardizing public health and ecosystems downstream.

The Supreme Court muddied the waters

The Obama administration’s Clean Water Act rule is an effort, rare among the mature environmental statutes, to limit that local discretion and reestablish a nationwide standard. The rule is responding to a pair of confusing Supreme Court decisions that challenged the CWA’s jurisdiction over tributary streams and wetlands — which, if polluted, allow pollution to wash into larger rivers and lakes.

In these decisions, issued in 2001 and 2006, the high court offered a variety of potentially conflicting criteria for deciding which waters were subject to CWA protections. In the 2006 decision, the court even failed to reach a majority opinion.

Since then, district and appellate courts have applied these tests in different ways. The result has been to reduce CWA enforcement overall, as regulators seek to avoid lengthy and expensive court battles, and to make policing of water quality even more inconsistent.

The newly released rule clears up much of this confusion by defining categories of tributaries and wetlands that meet the Supreme Court’s criteria for protection and by explicitly exempting other categories, such as stock ponds and irrigation ditches.

Don’t fear the feds

Bringing more of the nation’s streams and wetlands under the umbrella of federal protection is good news for states. It would shift the expense and burden of regulation away from state governments and onto federal agencies.

Even where states still have to enforce the law, the new rule’s clarity will reduce the costs of deciding where a state has jurisdiction and responsibility. And the rule will give states more control over their own water quality, because they’re in less danger of neighboring states sending pollution down the stream.

States recognize these benefits. Back in 2006, more than 30 states filed a Supreme Court amicus brief arguing for continued federal wetlands protection. Many of the states signing on to that brief don’t usually push for strong environmental regulations — but they recognized that without the federal government overseeing wetlands, states would be paying to clean up each others’ water pollution.

Surface tension: Cleaner water or states’ rights?

So how will conservative state politicians react? Will they welcome the proposed rule’s promise of taxpayer savings and reduced state effort — or will they oppose the rule on political principle, rejecting increased federal regulation?

In many of the right-leaning states that supported federal oversight in the 2006 brief, Democratic attorneys general have since been replaced by Republicans. Some of those states now seem ready to join the charge with the agriculture and business communities against the new policy. But others may be willing to quietly accept this reassertion of federal authority. If they do, it is a sign that state interests may still matter in a polarized political environment.

U.S. environmental policy is always in tension between responding to local conditions and maintaining minimum protections for everyone. For decades, court decisions and failures in state enforcement have meant inconsistent water quality — and states have suffered from their neighbors’ dirty water.

The proposed new Clean Water Rule offers states more control over their own water quality, at the cost of stronger federal oversight. States will have to decide if they have more to fear from the feds or from their neighbors.

Megan Mullin is an associate professor of environmental politics at Duke University.