The federally-led strategy to restore the Chesapeake Bay is ahead of schedule for two of three key pollutants, although the cleanup is being held up in some areas by budget concerns, the Environmental Protection Agency said in two reports recently released. Reducing nitrogen and sediment pollution is ahead of schedule, while phosphorus reduction is behind schedule. The three are the key pollutants in the bay. Nitrogen and phosphorus come from sources including sewage, fertilizer, auto and power plant emissions. Once they enter the Chesapeake and waterways that feed the bay they can spur oxygen-robbing algae blooms. Sediment that runs off lawns, development sites, farms, roads and other areas can cloud water and bury bay grasses, which provide food and habitat for a number of species. EPA spokesman Greg Barranco said a new tracking and reporting system for phosphorus offset most of the reductions for the pollutant.