The U.S. Environmental Protection Agency and Department of Agriculture sent a joint letter to states and tribal groups this week encouraging “reinvigoration” of efforts to reduce agricultural runoff and acknowledging “nutrient pollution continues to be widespread, particularly in the Mississippi River Basin.”The letter sent Tuesday offers state environmental and agricultural agencies one-on-one meetings with the EPA and USDA to identify ways to reduce nitrates and phosphorus flowing into waterways.It was sent two days after The Gazette published “Treading Water,” a four-month project documenting how little progress has been made in reducing nitrates and phosphorus washing into the Mississippi River and down to the Gulf of Mexico.