WASHINGTON (AP) — The Obama administration is moving to protect the nation's drinking water with rules that clarify which smaller streams, tributaries and wetlands are protected from pollution under the Clean Water Act.

Two Supreme Court rulings had left the reach of the law uncertain. The rules issued Wednesday by the Environmental Protection Agency and the U.S. Army Corps of Engineers are designed to clarify which smaller bodies of water are federally protected.

EPA Administrator Gina McCarthy said the rule will only affect waters that have a "direct and significant" connection to larger bodies of water downstream that are already protected.

The rules have already run into deep opposition from farm groups and the Republican-led Congress. The House voted to block the regulations earlier this month, saying they amount to overreach.