BALTIMORE —Heavy rains and a hot summer harmed the Chesapeake Bay’s health last year, earning it the second worst grade on a yearly report card issued Tuesday by the University of Maryland’s Center for Environmental Science.
The center gave the bay a D+ in 2011, scoring only slightly better than in 2003, the worst year for bay health since the assessments began in 1986.
Heavy spring and fall rains washed pollutants and sediments into the bay, and a hot, dry summer spurred algae blooms that lower oxygen levels.
Flood waters from Tropical Storm Lee brought up to an inch and a half of sediment into the upper bay. Meanwhile, water clarity continued to decline along with losses in bay grasses.
Only two regions — the lower Western Shore of the bay, which got a C, and the Patapsco and Back Rivers improved, but still got a D-. The rest declined or remained the same.
Virginia’s Rappahannock, for example, went from a C- to a D+ as grasses suffered significant declines. The Potomac River remained at a D, suffering declines in water quality but not enough to change its grade.
The Patuxent and Elizabeth rivers received failing grades. The failing grade was the first for the Elizabeth, which has been polluted by industry and shipyards, and scored a grade of 0 for three indicators.
Last spring, the bay got 42 out of 100 possible points, down from 46 the year before and the first drop in four years.
Rains carry sediments that can cloud water and bury bay grasses as well as pollutants such as nitrogen and phosphorus that can lead to oxygen-robbing algae blooms.
Last year, heavy spring flows and two fall storms “brought a huge amount” of pollution and sediment into the bay, said Caroline Wicks, a UMCES project manager who presented the results.
The weather this year has been cooperating so far with dry weather that hasn’t washed much pollution into the bay, Wicks said.
“Hopefully, that means we’ll have better scores this coming summer. However, with the warmer air temperatures we might have another hot, dry summer,” Wicks said.
Nicholas DiPasquale, director of the federal Environmental Protection Agency’s Chesapeake Bay Program, said the bay had received what he considered a failing grade in the report card, but also noted the report card “gives a snapshot in time.”
“We also have to look at the long-term, and we see a lot of positive indicators,” DiPasquale said.
A recent study found that over the past 60 years the frequency duration of low oxygen dead zones in the bay has decreased and the large Susquehanna Flats beds of grasses in the northern bay survived last fall’s rains and flooding relatively unscathed — signs that restoration efforts building resiliency back into the bay’s ecosystem.
However, DiPasquale said the bay was at a critical point in the EPA’s restoration strategy and the federal, state and local governments “need to move from planning to implementation” of further pollution reduction programs as proposed.
William Dennison, vice president for science applications at UMCES, said thinking locally is the key to bay restoration.
“What we’re seeing is that the bay as a whole has some issues, but if we can work at the smaller scale, the local streams and waterways, improve those, then we’ll eventually filter into the tributaries and the bay as a whole, and see the report card scores for the bay improve,” Dennison said.