Chesapeake Bay cleanup efforts appear to be working, according to a study released recently analyzing 60 years of water quality data.
The study, conducted by Johns Hopkins University and the University of Maryland Center for Environmental Science, found that statewide measures to reduce the flow of fertilizers, animal waste and other bay watershed pollutants have worked to reduce the size of mid- to late-summer oxygen-starved “dead zones,” areas where plants and water animals cannot live, in deep channels of the bay. These dead zones have been on the decline since the 1980s, when the state and federal government started the Chesapeake Bay Program, aimed at cutting nutrient pollution and restoring water quality and the health of the bay.
“I was really excited by these results because they point to improvement in the health of the Chesapeake Bay,” lead author of the study Rebecca R. Murphy, a doctoral student in the Department of Geography and Environmental Engineering at Johns Hopkins, said in a statement. “We now have evidence that cutting back on the nutrient pollutants pouring into the bay can make a difference. I think that’s really significant.”
“Continuing nutrient reduction remains critically important for achieving bay restoration goals,” UMCES Don Boesch said in a statement.
The bay’s health deteriorated during much of the 20th century, contributing to a drop in fish and shellfish populations, according to a release about the study, adding that environmental experts blamed the trend largely on a surge of nutrients entering the bay from farm fertilizer, animal waste, water treatment discharge and atmospheric deposition. Heavy spring rains typically flush these chemicals, primarily nitrogen and phosphorus, into the Susquehanna River and other waterways that empty into the Chesapeake, and the nutrients promote the prolific growth of algae.
When the algae die, their remains sink to the bottom of the bay, where they are consumed by bacteria. As they dine on algae, the bacteria utilize dissolved oxygen in the water, leading to a condition called hypoxia, or depletion of oxygen. As this process continues through the spring and summer, the lack of oxygen turns vast stretches of the bay into dead zones. Hypoxia sometimes results in fish kills, when a local population of fish die off.
Researchers now link the decrease in dead zones with the launch of state and federal efforts to reduce the flow of algae-feeding pollutants into the bay. Farmers have been encouraged to plant natural barriers and take other steps to keep fertilizer out of waterways that feed the bay, water treatment plants are pulling more pollutants from their discharge and air pollution control measures have curbed the movement of nitrogen from the atmosphere into the bay.
The study also found that troublesome early summer jumps in dead zones actually were influenced by climate forces, not by the runoff of pollutants, and according to the release, researchers believe the early dead zone conditions would have been even worse without efforts to rein in pollutants.
Co-author of the study Michael Kemp, an ecologist with UMCES, said the findings reinforce that even though the Environmental Protection Agency’s mandated Watershed Implementation Plan will be costly for state and local governments to carry out, the science behind it will work. Under the plan, each jurisdiction in the bay watershed, including St. Mary’s County, will be required to meet total maximum daily pollutant loads — TMDLs — for sediment, phosphorus and nitrogen entering the bay and its tributaries.
“It’s reassuring in that [the study] demonstrates that the reduction in nutrient loading required to fulfill the TMDL levels will in fact improve water quality,” Kemp said. “If there was any doubt that this is a useful sacrifice for people to make, there will be benefits.”
Already positive results are happening, he added, as efforts at reducing nitrogen pollution from smokestacks and automobiles for purposes of protecting human health have simultaneously improved bay health as well by reducing nitrogen that enters the water through the air.
“That part is going well,” Kemp said. “It doesn’t mean the other parts of the TMDL don’t need to move forward, but it means we’re getting benefits already.”
mrussell@somdnews.com
