The Obama administration on Tuesday moved to clarify a rule within the Clean Water Act (CWA) that would limit pollution discharges into streams, waterways and wetlands, a proposal that is drawing ire from lawmakers and business groups, including the Senate’s Energy Committee chair.

The proposal by the U.S. Environmental Protection Agency (EPA) and the U.S. Army Corps of Engineers would clarify which waters are under CWA oversight. The Army Corps and states process permits for working in the nation’s waterways, while EPA enforces pollution laws.

“We are clarifying protection for the upstream waters that are absolutely vital to downstream communities,” said EPA Administrator Gina McCarthy.

Streams and wetlands trap floodwaters, recharge groundwater supplies, remove pollution, and provide fish and wildlife habitat. They also are economic drivers “because of their role in fishing, hunting, agriculture, recreation, energy and manufacturing.”

The question of whether isolated streams and wetlands are protected under the CWA has been in dispute for more than 10 years. The Obama administration had delayed issuing a rulemaking in its first term because of strong objections by business groups.

Addressing the charge that the administration was overreaching with the proposal, McCarthy said opponents were concerned about an expansion of the CWA. “There has not been,” she said. Current exemptions under the CWA that are used by developers would not be eliminated.

Specifically, the proposed rule clarifies that under the CWA and based on scientific data, most seasonal and rain-dependent streams are protected, and wetlands near rivers and streams are protected. Other types of waters that may have more “uncertain connections” with downstream waters would be evaluated through a case-specific analysis.

A study by the Environmental Law Institute found that 36 states now have legal limits on their abilities to fully protect waters that aren’t covered by the CWA, federal officials noted.

The proposal is designed to clarify the effects of the 2006 Rapanos decision by the U.S. Supreme Court, which narrowed the federal government’s ability to enforce pollution laws for smaller streams and bodies of water. The proposed regulation is based on a scientific study completed by EPA a few months ago about how discharges from small bodies of water, such as streams that flow only at certain times of the year, affect the downstream.

The high court’s ruling opened the door for the government to enforce pollution laws if scientific studies were to find a link between the small water streams and their effect on downstream quality effects. The rule would not protect “any new types of waters that have not historically been covered under the CWA,” federal officials noted.

However, the regulatory move was not welcomed by some lawmakers — Democrats and Republicans — or by some industry groups. Opponents claimed the rule was an overreach that could delay projects and permits sought for dredging, filling or drainage.

Louisiana Democratic Sen. Mary Landrieu, who chairs the Energy Committee, plans to “work with colleagues on both sides of the aisle to find a legislative solution to reverse this unfair, unwise and unnecessary decision.”

Sen. David Vitter (R-LA), minority leader on the Senate Environment and Public Works Committee, said the EPA was undertaking “one of the most significant private-property grabs in U.S. history,” giving “the federal government outright permitting authority over virtually any wet area in the country.”

The proposed rule “is a massive expansion of power over the nation’s water resources,” said Sen. Jim Inhofe (R-OK). “The Clean Water Act is written to include only navigable waters, but with this new rule, the agencies are giving themselves the authority to regulate everything from the nation’s largest rivers to small irrigation ditches found on family farms in Oklahoma.”

Lawmakers complained that the Obama administration continues to circumvent Congress inappropriately by proposing rules through regulatory agencies. The administration used a similar process to propose regulations to limit carbon emissions from coal-fired power plants.

However, many praised the proposal, including the American Sustainable Business Council (ASBC), which represents more than 200,000 businesses in the United States.

“American business has always depended on the availability of clean water for its success, and EPA’s regulation in this area historically has been a prime example of the vital partnership between business and government,” said ASBC policy director Richard Eidlin. “Degradation and loss of wetlands or small streams can increase the risk of floods, threatening businesses. Moreover, dirty, polluted water creates unnecessary and sometimes very difficult economic challenges for communities and businesses alike. [Tuesday’s] action by the EPA is good for the environment and good for business.”

Natural Resources Defense Council’s Peter Lehner said opponents “will claim that this proposal is rooted in politics. In fact, it is firmly rooted in law and science. The Supreme Court decisions that led to this rollback actually permitted the EPA and the Corps, based on scientific evidence, that smaller waters significantly influence water conditions downstream, to close the gap in protections.

“These agencies are using strong, solid science, together with the venerable 41-year-old Clean Water Act, to protect and safeguard our waters and thus our health…We all have a right to clean water. Protecting that right means protecting our natural water systems as a whole, and not just some individual bodies of water. Pollution doesn’t stay put…”