The Chesapeake Bay report card compares 20 indicators (dissolved oxygen, nitrogen, phosphorus, turbidity, water quality index, chlorophyll a, water clarity, conductivity, aquatic grasses, benthic community, fish community, temperature stress, protected lands, social index, walkability, heat vulnerability index, household income, affordable housing, income equality, jobs growth) to scientifically derived thresholds or goals. These indicators are combined into an Overall Health Index, which is presented as a subregion percent score.