EASTON — Even though the overall health of the Chesapeake Bay didn’t change much, according to the annual health report card by the University of Maryland Center for Environmental Science, Eastern Shore rivers mostly showed a degradation in health.
Overall, the Chesapeake Bay scored a 45 percent, a C, which is nearly the score from 2012 despite a 2013 with above average rainfall and record heat.
“Nutrient and sediment pollution carried by stormwater are important factors in Chesapeake Bay health,” said Bill Dennison, vice president for science applications at UMCES. “Based on patterns in rainfall and report card grades for several reporting regions, we conclude that it is not the rain that affects the report card scores; it is what the rain carries.”
According to the report card, Eastern Shore waterways bordered by agricultural lands continue to degrade.
The Choptank River scored a C-, while Upper Eastern Shore tributaries like the Elk, Sassafras, Chester and Miles rivers, scored Ds.
According to the report card, rivers on the Shore had poor grades in 2013 due in part to more than 50 inches of rainfall on the Delmarva peninsula last year. Excess rainfall resulted in more runoff from fertilizer and chicken manure applied to fields, which contributed to the score, the report states.
“While the overall grade for the Bay did not change, we are seeing a continuing degradation of the Eastern Shore waterways that are dominated by agriculture,” Dennison said. “This tells us the importance of local management actions for our rivers and streams.”
Rivers west of the Bay generally improved in 2013, Dennison said, partly due to wastewater treatment plant upgrades.
According to UMCES, the James River at the southern end of the Bay is showing a positive trend.
Besides the wastewater treatment upgrades reducing nitrogen and phosphorus entering the Bay, the watershed also is improving partly because of a higher percentage of forested land cover acting as buffers and preventing pollution from entering waterways during rain events.
Western shore tributaries like the Patapsco and Back rivers also improved due to wastewater treatment plant upgrades and a decline in atmospheric nitrogen deposition triggered by the implementation of the Clean Air Act, according to UMCES.
However, the Bay is becoming murkier, and that is attributed to higher rainfall amounts, in addition to higher chlorophyll levels, according to UMCES.
Also, nitrogen levels show improvement over time, and underwater grasses also saw a rebound in 2013. But, improved underwater grass levels are largely due to a boom in widgeon grass, which is known as a boom-and-bust species, in the mid-Bay, so the levels may still decline in 2014.
The 2013 report card includes a new addition — assessments of three fisheries: Bay anchovy, striped bass and blue crab.
Despite earlier reports that blue crab levels are declining, the UMCES report card suggests that blue crab levels are on the rise, although they still haven’t hit target levels of 215 million adult females.
Similarly, a three-year average from 2011 to 2013 of striped bass values is up, but the single-year average is down, the report states.
Meanwhile, Bay anchovy levels have been rising since 2008.
UMCES also is working on a Climate Change Resilience Index to measure the resilience of the Bay to impacts of climate change, looking at several climate change impacts like sea level rise, increasing water temperatures, increasing storm frequency and intensity and ocean acidification.
Additional indicators UMCES will consider for climate change resilience include the impact on coastal wetlands, submerged aquatic vegetation, bacteria and other pathogens and fish and shellfish recruitment.