Perhaps without even knowing the implications of their actions, some members of Congress are working to undermine treaty rights.

To benefit corporate interests, Sen. Steve Daines (R-Mont.) and Rep. Ryan Zinke (R- Mont.) have led efforts to change the way the U.S. Army Corps of Engineers evaluates a project’s impact on tribal treaty rights.

SSA Marine wants to build North America’s largest coal terminal in our sacred Salish Sea in the Pacific Northwest. If built, the terminal would allow monster-size ships—vessels that are too big to pass through the Panama Canal— to travel across the treaty-protected fishing grounds and near the sacred sites of the Lummi, Tulalip, and several other tribes with guaranteed fishing rights. Years of research show that the proposed terminal at Cherry Point violates Lummi’s fishing rights and cannot be mitigated. It’s the Corps’ trust responsibility to conduct a thorough and separate review of the evidence and evaluate the project’s impact to Lummi’s treaty rights.

The terminal would allow Montana coal to be shipped to China for big profits, so Zinke recently introduced an amendment (H.R. 22) that would prohibit the Corps from reviewing the Gateway Pacific Terminal project for its impact on treaty rights. The lawmakers have also sent a letter to the agency, signed by 32 of their colleagues in Congress, asking the Corps to stop its review of the proposed terminal’s impact on Lummi Nation’s treaty rights. This reflects a deep misunderstanding of the role of a federal trustee. The Corps has a trust responsibility to uphold federal treaty rights.

It’s unconscionable that members of Congress, including some members who serve on the Indian Affairs committees of the House and Senate, would take action to chip away at treaty rights. We won’t let this happen.

A growing alliance of treaty and executive order tribes is sending a strong message to Congress to protect treaty rights. Alliance leaders from the Lummi, Tulalip, Hoopa Valley, Nooksack, Lower Elwha, Yakama and Spokane tribes are meeting in D.C. this week with members of Congress to protect the sacred sites and treaty-protected fishing grounds of Cherry Point.

Our past leaders were forced to cede our lands, sometimes under threat of death, in exchange for our tribes’ guaranteed rights. Within these agreements, our ancestors stood strong to protect things we hold sacred as a people—the places we fish, the sites where we pray, the best locations to gather our traditional medicines, and the holy ground where we lay our loved ones to rest.

Promises were made by the federal government and we stand together to protect these hard-won rights. By barring a federal agency from carrying out its trust responsibility, Congress would set a dangerous precedent for all of Indian Country.

We stand together to tell Congress that any action to interfere with this process and to erode our treaty rights is unacceptable. We urge Congress to keep the promises made by the federal government and vote no on any legislation preventing the Corps from doing its job as a trustee.

Ballew is chairman of Lummi Indian Business Council. Sheldon is chairman of the Tulalip Tribes Board of Directors.