The largest estuary in the United States is about to get a makeover. The federal government released plans on Thursday designed to reignite cleanup efforts in Chesapeake Bay, a 200-mile long watershed connected to six different states. Pollutants from farming and urban development have long plagued the area. Run-offs from livestock manure, fertilizer, and sewage increases the algae in the bay, which depletes underwater oxygen and creates “dead zones” where sea life cannot survive. Plans to purify the region began a quarter century ago, but little progress has been made because efforts were mainly voluntary with no federal oversight. The Environmental Protection Agency hopes to turn things around with aggressive federal involvement and penalties that hold guilty states accountable for their actions.