Record amount of freshwater impacts Bay water quality
"The Chesapeake Bay Program announced today that an estimated 38% of the Chesapeake Bay and its tidal tributaries met clean water standards for clarity (measured by underwater grass abundance), dissolved oxygen and chlorophyll a (a measure of algae growth) between 2016 and 2018. This score is lower than the record high 42% from the previous reporting period but is still the fifth highest estimate of water quality standards attainment since 1985.
This four percentage point decrease from the previous assessment period is due in large part to a decline in dissolved oxygen in the open waters of the Bay, those areas beyond the shoreline and shallows. Dissolved oxygen is necessary for the survival of the Bay’s aquatic species, and is a factor in the annual dead zone. However, dissolved oxygen conditions in deep water habitat (depths greater than six feet) and measures of chlorophyll a along the Bay’s surface shows improvement from the 2015-2017 assessment period, which may indicate increasing resilience. However, water quality must improve in 62% of the Chesapeake Bay and its tidal tributaries if the estuary is to function as a healthy ecosystem.
Water quality is influenced by nitrogen, phosphorus and sediment loads delivered from the watershed and varies each year due to land use and river flow. The U.S. Geological Survey (USGS) reports that between October 2017 and September 2018, river flow to the Bay measured an above-average 70.5 billion gallons per day, the highest recorded amount since 2011. . ."
For more information:
USGS updates trends for nutrients and sediment in the Chesapeake Bay Watershed