Slow Water Affects Chesapeake Bay Restoration

Pull a bucket of water from the Chesapeake, and each drop will most likely be from a different place and tell a different story about how it got there.

For some, it’s been a pretty short trip that started as a drop of rain that smacked into a parking lot, then flushed quickly into a local stream and reached the Bay a few days later.

Some may have soaked into Piedmont soil a decade ago and only recently emerged in a stream after traveling through groundwater.

Some drops from the Eastern Shore may have fallen as rain when John F. Kennedy was president, seeped into the Delmarva’s slow-moving aquifers, and now, after 50 years, finally made it to the Bay.

A few may have even started their journey before the United States was a country.

Collectively, the drops offer more than a history lesson; they provide a cautionary tale about how rapidly people should expect to see significant water quality improvements in the Chesapeake.

All of the drops of water absorbed nitrogen, which readily dissolves in water, and is one of the major pollutants in Chesapeake Bay. But they likely all contain different amounts of nitrogen, because they absorbed the nitrogen at different times, in different places, when more or less was being applied to fields and when nitrogen-reducing management practices might not have been in place.

For example, the “youngest” water in the bucket might carry reduced amounts of nitrogen because cover crops, an effective nitrogen reducing practice, were planted when it fell as rain. But older water that predates cleanup actions may contain higher levels of nitrogen.

“It’s really a mixture of water ages that ends up in a stream,” said Scott Phillips, Chesapeake Bay coordinator for the U.S. Geological Survey. “Some water travels over the land as storm runoff and is really young. Even the groundwater discharged into the stream is a mixture of ages. It is a complicated situation of many ages of water and associated nitrogen going into a stream.”

That mixture complicates efforts to sort out overall water quality trends because improvements are often masked by “old” — often dirtier — water that is still moving through the system.

Scientists refer to the delay from when a pollution control action is taken to when it results in a water quality improvement as “lag time.” The concept is not new, but recent reports suggest lag times may delay the attainment of Bay cleanup goals longer than previously recognized — bedeviling efforts to show that billions of dollars of investments are reaping significant benefits to the Bay and its tidal rivers.

“The potentially long periods of these lag times do not constitute an excuse for inaction, but they do constitute a reason for being patiently realistic about the time scale for observing results,” said a recent report from the Scientific and Technical Advisory Committee to the state-federal Chesapeake Bay Program partnership

A new study from U.S. Geological Survey scientists showed just how much patience may be needed. It found that so much of the rainfall on the Delmarva Peninsula soaked into the groundwater, and its groundwater moved so slowly, that roughly a third of that water reaching streams is more than half a century old.

That means much of it still predates the spike in agricultural fertilizer use that occurred in the 1960s and ’70s. As a result, even though some “young” groundwater is part of the mix, the overall nitrogen concentrations reaching Eastern Shore rivers through groundwater are continuing to rise, and in many places it will take decades for that “old” groundwater with high nitrogen concentrations to be flushed from the aquifers.

The scientists examined the concentrations of chlorofluorocarbons and radioactive particles in the groundwater samples drawn from springs in the Delmarva Peninsula to determine its age. Since the 1940s, different levels of CFCs have entered the atmosphere each year and the ratio of tritium to helium in particles has varied as the result of nuclear tests. Those concentrations are reflected in the rain, which absorbs the elements, giving scientists a way to age the water when it emerges from springs.

The study, led by USGS scientist Ward Sanford, concluded that a 13 percent reduction today in the amount of nitrogen reaching groundwater was needed simply to keep overall nitrogen levels steady in 2050.

A diet with lag times?

A bucket of water pulled from the Bay in 2025 will likely be cleaner than one pulled out today — just as one pulled out today would, in most areas, be cleaner than one in 1990. But it likely will have far more nitrogen, phosphorus and sediment than was prescribed by the Chesapeake Bay pollution diet, or total maximum daily load, which set limits on the amount of nitrogen, phosphorus and sediment that can enter the Bay from each state and major tributary.

Those limits are intended to help the Bay and tidal portions of its tributaries meet water quality standards for dissolved oxygen, water clarity and chlorophyll a (a measure of algae). Those standards are aimed at protecting aquatic life.

The TMDL calls for all actions needed to reduce pollution levels to acceptable levels to be in place by 2025. But because of lag times, the TMDL made no prediction of when water quality standards would actually be met throughout the Chesapeake.

If lag times are not factored into decision-making and better communicated with the public, support for cleanup efforts could be undermined, the Scientific and Technical Advisory Committee report cautioned. “We have to do a better job of communicating that these anticipated lags are in the system and that improvement is not going to happen overnight,” said Gene Yagow, a senior research scientist in Virginia Tech’s Biological Systems Engineering Department, and one of the lead authors of the report.

Beth McGee, senior scientist with the Chesapeake Bay Foundation, said she is concerned about maintaining public support if tangible progress is slow. “How are you going to maintain momentum when currently we are hard-pressed to point to many success stories?” she asked. “I think the solution is to look for success stories, to find areas where we have done a lot of implementation and where we expect things to turn around.”

Bay officials are seeking to bolster their communication of the difficult issue.

For instance, Environmental Protection Agency officials are also pushing efforts to better quantify the level of water quality improvement that can realistically be expected in 2025. While the Bay wouldn’t fully attain water quality standards by then, such predictions could help show that actions are having expected responses.

“Obviously, water quality standards attainment is the ultimate goal,” said Jon Capacasa, director for water quality protection with the EPA’s mid=Atlantic region. “But the public can derive a lot of benefits from the incremental reductions in nutrients and sediments to the Bay along the way. It is not one big on/off switch in 2025.”

Pollution control efforts should also get a boost in coming years. Efforts to upgrade wastewater treatment plants have progressed rapidly, and officials expect most to be upgraded by the end of next year.

But after 2014, most of the nutrient reductions will have to come from nonpoint sources — mainly runoff from farms, urban and suburban areas and other land uses. With each passing year, smaller portions of the nutrient control actions being implemented will be fully felt in the Bay and tidal rivers by 2025. Portions of those improvements will continue to be offset by “old” nutrient pollution emerging from slow-moving groundwater.

But over time, the hypothetical bucket of water drawn from the Bay should increasingly reflect improvements from the nutrient controls efforts now under way — and those that will be taken in the near future.

“People like myself, we wouldn’t be in this business we are in if we didn’t have some level of optimism,” said Rich Batiuk, associate director for science with the EPA Chesapeake Bay Program Office. Lag times, he said, provide a reason to keep taking action — not to give up.

“Two generations back, they didn’t see the level of degradation that would be caused by high nitrate levels in the groundwater,” he said. “Yes, it might be a future generation that is actually going to see the full effect of what we do today. But we have to do it.” Distributed by Bay Journal News Service.

By Karl Blankenship
Bay Journal News Service