Southern Arizona representatives Raúl Grijalva and Tom O'Halleran have ask for a formal announcement on the banning of uranium mining near the Grand Canyon in a letter to U.S. Secretary of the Interior Ryan Zinke.
The letter said the Interior Department has made such a promise in tweets, but that the members of Congress want something more formal.
There are hundreds of abandoned mines near the Grand Canyon. The representatives said the clean-up of those mines has already cost more than $1 billion.
Representatives Ruben Gallego and Kyrsten Sinema also signed the letter.