The Trump administration on Tuesday took a major legal step toward repealing a bitterly contested Obama-era regulation designed to limit pollution in about 60 percent of the nation’s bodies of water.

The rule, known as Waters of the United States, or Wotus, had extended existing federal protections of large bodies of water, such as the Chesapeake Bay and Puget Sound, to smaller bodies that flow into them, such as rivers, small waterways and wetlands. Issued under the authority of the 1972 Clean Water Act, the rule has been hailed by environmentalists. But farmers, ranchers and real estate developers oppose it as an infringement on their property rights.