Chesapeake Bay health improved to a C in 2012

Chesapeake Bay health improved to a C in 2012 and could indicate a reverse in course of declining health, according to an assessment by scientists at the University of Maryland Center for Environmental Science. The overall grade was a C, up from a D+ in 2011, and overall Bay health appears to be slowly increasing since 2006.

“I’m cautiously optimistic about the health of the Chesapeake Bay,” said Bill Dennison of the University of Maryland Center for Environmental Science. “We are seeing progress in our efforts to reduce nitrogen and phosphorus levels. In addition, water clarity, which had been declining, has leveled out—and may even be reversing course.”

The overall health of the Bay improved this year, from 38% in 2011 to 47% in 2012. Nearly all of the Bay health indicators—dissolved oxygen, water clarity, total nitrogen, total phosphorus, chlorophyll (the amount of algae in the water), and the benthic community—improved in 2012. Total nitrogen seems to be improving over time, while aquatic grasses have been declining for several years now.

Factors that contributed to 2012 health include:

- Tropical Storm Lee: Rain for Tropical Storm Lee (September 2011) brought tons of sediment and fresh water to the Upper Bay. However, it did not affect 2012 water quality as much as expected.

 - Spring and summer conditions: High spring flows were followed by a summer drought that reduced the amount of nutrients entering the Bay through runoff, indicating that nutrient reduction efforts on land appear to be working.

- Hurricane Sandy (October 22-31) did not bring as much sediment to the Bay as Tropical Storm Lee and occurred later in the year. As a result, any negative impact on Bay health was minimal.

“Hurricane Sandy narrowly missed Chesapeake Bay in late October, and there was little adverse environmental impact on the Bay,” said Dennison. “Fortunately, the legacy of Tropical Storm Lee in 2011 also did not appear to manifest itself in 2012 water quality.”

Reporting regions with significantly improving trends were the Upper Western Shore, Upper Bay, James River and Elizabeth River. However, the Mid Bay region showed a significantly decreasing trend--indicating that Mid Bay health is declining. The worst reporting area grade was the Patapsco/Back Rivers (F) and the highest was the Lower Bay (B-).

The report card rates 15 reporting regions of the Bay using seven indicators that are combined into a single overarching index of health.

The University of Maryland Center for Environmental Science’s Integration and Application Network produces several report cards to assess the health of Chesapeake Bay waterways to enhance and support the science, management and restoration of Chesapeake Bay. For more information about the 2012 Chesapeake Bay Health Report Card including region-specific data and downloadable graphics, visit