Just 29.6% of the Chesapeake Bay and its tidal waters fully attained their water quality goals in the three-year period of 2018-20, according to new figures from the state-federal Bay Program partnership released Sept. 14.

That was the third consecutive annual decline in the Bay’s overall water quality, much of which was blamed on the impact of unusually high rainfall in 2018 and 2019, which drove more water-fouling nutrients off the land and into the Bay.

Water samples in bottles

Water samples from the Choptank River in Maryland await examination.

Before those events, 42.2 % of tidal waters had achieved their goals in the 2015-17 assessment period, the highest since Baywide water quality monitoring began in 1985.

“In the past, the Bay responded positively during periods of average river flow but had short-term declines due to the effects of Hurricane Isabel in 2003 and Tropical Storm Lee in 2011,” said Peter Tango, the Bay monitoring coordinator with the U.S. Geological Survey. “The high river flows in 2018 and 2019 have caused another short-term decline in the health of the Bay.”

The Chesapeake’s water quality goals are designed to ensure that Bay creatures — from bottom-dwelling worms to striped bass swimming along the surface — have enough oxygen to survive, and that underwater grass beds have clear enough water to thrive. 

Attaining those water quality standards throughout the Bay has been the goal of the multi-billion-dollar nutrient reduction efforts in recent decades. Excess amounts of nitrogen and phosphorus spur algae blooms that cloud the water, causing the loss of critical underwater grass habitats. When the algae die, they sink to the bottom and decompose in a process that draws oxygen from the water, causing dead zones that can be lethal to fish and other aquatic life.

Although progress has been made, the region remains off course in meeting its goal of putting all needed nutrient control practices in place by 2025. While overall nutrient trends in the Bay’s largest rivers — the Susquehanna, Potomac and James — are generally improving, those in many other areas are mixed or degrading. 

Officials evaluate water quality in the Bay and the tidal portions of major tributaries by examining measurements over three years, which reduces the influence of a single year’s weather on the Baywide assessment.

Nutrient reductions had generally helped improve water quality over the years, before the recent setback. In 1985-87, the first assessment period, only 26.5 % of tidal waters met water quality goals.

Still, the new data is a reminder that while nutrient reduction progress has been made, those efforts are not great enough to offset the impacts of climate change, which is expected to bring more, and more intense, rain. That, in turn, will drive more nutrients off the land and into waterways

“The Chesapeake Bay jurisdictions are well aware that the additional and more intense storms caused by climate change will require more to be done to reduce pollution,” said Beth McGee, director of science and agricultural policy for the Chesapeake Bay Foundation.

She said the states needed to “accelerate efforts and prioritize practices, like planting more trees and using green infrastructure, that will reduce flooding and sequester carbon, as well as reducing polluted runoff.”

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