Congressional representatives in Oregon and California plan to closely monitor the review process of a mining claim affecting the Smith River watershed and Rogue River-Siskiyou National Forest.

U.S. Reps. Peter DeFazio, D-Oregon, Sens. Ron Wyden and Jeff Merkley and Jared Huffman of California sent a letter to the U.S. Forest Service Thursday urging the agency to regularly advise lawmakers as they review a mining claim in the Southern Oregon Mineral Withdrawal Area, according to a press release.

The withdrawal area includes the North Fork Smith River in Oregon, which provides drinking water to Del Norte County as well as critical salmon habitat.

The lawmakers sent the letter to Merv George, the new Rogue River-Siskiyou National Forest supervisor, and Glenn Casamassa, the new regional forester for USFS Region 6, the release reads.

“As you are new to your respective positions, we want to inform you of our long-standing interest in protecting lands within the withdrawal area,” the letter states. “As you are aware, the withdrawn area contains the headwaters of Hunter Creek and Pistol River, as well as sections of the Rough and Ready and Baldface creeks.

“It also provides some of the cleanest drinking water in the nation to communities in Southwest Oregon and Northern California, and contains one of the highest concentrations of rare and endemic plants in North America. There is strong community support for the withdrawal by residents, businesses and local officials. We ask that you exercise the utmost due diligence as you move forward.”

In 2017, lawmakers secured a 20-year ban on new mining projects within the Smith River watershed, the Rough and Ready Creek watershed and 17 miles of the Chetco River, the press release reads.

Though the withdrawal prevents new mining claims from being established, companies with existing claims can mine within the area. However, the forest service must “rigorously review all mining claims” to ensure their validity, according to the release.