This article is Part 4 of our special report, The Bay's Pollution Diet: Is it Working? See also: Part 1, Chesapeake cleanup may lose race to 2025 goal, but presses on; Part 2, New nutrient reduction goals reflect updated science, data, computer modeling; and Part 3, Success of Chesapeake’s restoration tied to PA, which lags far behind.
This December will mark the 35th anniversary of the original promise by regional leaders to work together to protect the water quality of the Chesapeake Bay — and the fish, crabs and other species that depend upon it.
More than three decades after it started, the cleanup effort still has a long way to go. In its latest water quality assessment, the state-federal Bay Program partnership found that just 40 percent of the Chesapeake’s tidal waters met agreed-upon goals for clarity, dissolved oxygen and chlorophyll.
That’s the best status report since the cleanup effort began, but still far from attaining water quality standards.
So how long will it take to get there?
“Decades,” said Rich Batiuk, the retired associate director for science with the U.S. Environmental Protection Agency’s Bay Program Office. “But I think, in another decade or two, we’ll see a different Chesapeake out there.”
Indeed, while it might take decades to meet Baywide water quality goals, people could see a substantially better Chesapeake much sooner — in fact, they are already seeing it. Last year, the Bay’s underwater grass beds exceeded 100,000 acres, a level not reached in decades.
Their resurgence demonstrates results from decades of often slow but steady work. But reaching goals for water clarity and oxygen concentrations throughout the Bay will be difficult.
The most recent plan to deliver a clean Bay, the Chesapeake Bay Total Maximum Daily Load or “pollution diet,” sets a 2025 cleanup deadline. But that doesn’t mean the Bay would be “clean” by 2025. The 2025 deadline is for states to implement all of the actions needed to meet water quality standards.
Even if that happens on schedule, there would be substantial delays before the impact of all of those actions would be felt in the Chesapeake. It can take many years for some runoff control practices, like newly planted streamside forest buffers, to become fully effective. And much of the nutrient pollution that enters the Bay and its rivers first travels through slow-moving groundwater.
Management practices such as cover crops can reduce the amount of nitrogen sinking into the groundwater, but it can take years to decades for the “old” groundwater — which predates the use of cover crops and other practices — to work its way out of the system.
During the years it takes for the full impact of those actions to be felt in the Bay, states will have to take even more pollution control actions to offset the impacts of population growth, new development and increasingly intense agricultural operations — just to hold the line on pollution.
Also, the 2025 cleanup deadline does not account for the substantial new efforts that will be needed to offset the filling of the Conowingo Dam reservoir on the Susquehanna River and increased precipitation from climate change — both of which deliver nutrients that were not accounted for when setting the current cleanup goals. At recent rates of nutrient reductions, additional efforts to offset those loads would take at least five more years. And then, as with current efforts, it would take additional time for their full impact to reach the Bay.
But there is good news. The nutrient reductions required by the TMDL were set to achieve water quality standards in the deepest areas of the Bay, where dissolved oxygen concentrations are lowest. But lesser amounts of nutrient reductions will trigger improvements sooner in many other areas, said Jon Capacasa, who is now retired but oversaw the development of the Bay water quality standards as the former head of EPA Region III’s water protection division.
“There is going to be a lot of change happening in the shallow reaches of the Bay, particularly where the habitat is most valuable, long before you return oxygen to the deep part of the Bay,” Capacasa said.
That’s already been seen with the re-cent expansion of underwater grass beds.
Another positive factor, scientists say, is that better water quality can kick-start other biological and chemical processes that lead to further improvements.
For instance, large underwater grass beds improve surrounding water quality, which in turn allows those beds to expand farther than might be predicted by nutrient reduction efforts alone. Scientists say that’s already happening in places around the Bay, including the Susquehanna Flats, an area that was nearly barren two decades ago but is now covered with thousands of acres of lush underwater meadows.
Recent research has shown that nutrient reductions have also triggered chemical-processing changes in deep areas of the Bay, resulting in better oxygen conditions than were predicted. While much of the Bay remains blanketed by a hypoxic (low oxygen) dead zone, the amount of anoxic (no-oxygen) water has been gradually shrinking.
Some believe that slight improvements in water clarity will activate still more changes. As light hits the bottom, it can spur the growth of certain bottom-dwelling algae species that help bind sediment, preventing it from being churned up and clouding the water.
In short, they say, parts of the Bay are near a “tipping point” at which Mother Nature will help improve conditions.
“That is really exciting,” said Beth McGee, senior water quality scientist with the Chesapeake Bay Foundation. “We know the Bay isn’t going to be saved by 2025. But the big unknown is what we are seeing now — the notion of a tipping point. We are seeing improvements.”
Scientists refer to that natural assistance as “positive feedback.” It has the potential to act “like a turbocharger” for the ecosystem by producing greater — and perhaps faster — improvements, said Bill Dennison, vice president for science applications with the University of Maryland Center for Environmental Science.
“We certainly have got the trajectory in the right direction,” he said. “That is the most important thing because that positive trajectory helps accelerate the feedback.”
“But we can’t backslide,” he added. “We have to continue to make progress.”