The Trump administration is scheduled to announce today a major rollback of the nation’s clean water regulations. The rule change decreases the number of waterways protected by the U.S. Clean Water Act. Critics warn this could result in expanded oil drilling and mining in once-protected areas and lead to an increase in chemical pollutants, including pesticide runoff. The proposal is the latest in the Trump administration’s efforts to weaken environmental laws after loosening regulations for car emissions, mercury and coal, and opening up previously protected areas for gas and oil drilling.