Since his first election in 1999, Doer has been a leading opponent of a water diversion in Devils Lake, North Dakota that many regard as posing a serious environmental threat to Manitoba. In 2005, the Canadian and American governments reached a non-binding compromise deal on the project that committed both sides to design an advanced filter to prevent environmental disruption. Doer initially described this agreement as a significant improvement over prior arrangements, but later criticized the North Dakota government for starting the water diversion before the deal was finalized. In May 2009, Doer said that Manitoba would invest more than $10 million in drainage improvements if North Dakota would agree to construct a permanent filter on its Devils Lake output. North Dakota Governor John Hoeven rejected the deal in the same month, arguing that the issues were separate.