text: In 2010 bay health improved slightly in terms of the overall health of its ecosystem, earning a rating of 31 out of 100, up from a 28 rating in 2008. An estimate in 2006 from a "blue ribbon panel" said cleanup costs would be $15 billion. Compounding the problem is that 100,000 new residents move to the area each year. A 2008 Washington Post report suggested that government administrators had overstated progress on cleanup efforts as a way to "preserve the flow of federal and state money to the project." In January 2011, there were reports that millions of fish had died, but officials suggested it was probably the result of extremely cold weather.
  The health of the Chesapeake Bay improved in 2015, marking three years of gains over a four-year period, according to a 2016 report by the University of Maryland Center for Environmental Science (UMCES). In 2021 scientists at the UMCES reported slight improvements in bay water quality compared to levels measured in 2020. The greatest improvements were seen in the lower bay areas, while the Patapsco River and Back River (Maryland) regions showed minimal improvement. Positive indicators included decreased nitrogen levels and increases in dissolved oxygen.
  The CBF reported that as of 2022 pollution control efforts in the bay have continued to show mixed results, with no improvement in levels of toxic contaminants, nitrogen and dissolved oxygen, and a small decrease in water clarity compared to 2020 levels (measured as Secchi depth). Oyster and rockfish populations in the bay have improved, but blue crab populations have continued to decline.