BILLINGS, Mont. (AP) — A bipartisan group of lawmakers from four U.S. states bordering British Columbia say the Canadian province needs to do a better job preventing mining pollution from fouling downstream rivers in the U.S.

Senators from Alaska, Montana, Idaho and Washington state in a joint letter Thursday asked British Columbia Premier John Horgan to commit to monitoring water quality along the province's U.S. border.

Environmentalists say that for decades Canadian mining has contaminated downstream waters, killing and deforming fish.

Alaska Republican Sen. Lisa Murkowski says reforms are needed in the British Columbia mining industry, including a system of financial assurances to protect against natural resource damages.

Horgan spokeswoman Jen Holmwood says his office received the letter but the premier was traveling Thursday and would review it when he returns.