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Bay Blog: lag-times

Feb
25
2014

Science shows restoration work can improve local water quality

Pollution-reducing practices can improve water quality in the Chesapeake Bay and have already improved the health of local rivers and streams, according to new research from the Chesapeake Bay Program partnership.

In a report released today, several case studies from across the watershed show that so-called “best management practices”—including upgrading wastewater treatment technologies, lowering vehicle and power plant emissions, and reducing runoff from farmland—have lowered nutrients and sediment in local waterways. In other words, the environmental practices supported under the Clean Water Act, the Clean Air Act and the Farm Bill are working.

Excess nutrients and sediment have long impaired local water quality: nitrogen and phosphorous can fuel the growth of algae blooms and lead to low-oxygen “dead zones” that suffocate marine life, while sediment can block sunlight from reaching underwater grasses and suffocate shellfish. Best management practices used in backyards, in cities and on farms can lower the flow of these pollutants into waterways.

Data collected and analyzed by the Bay Program, the University of Maryland Center for Environmental Science (UMCES) and the U.S. Geological Survey (USGS) have traced a number of local improvements in air, land and water to best management practices: a drop in power plant emissions across the mid-Atlantic has led to improvements in nine Appalachian watersheds, upgrades to the District of Columbia's Blue Plains Wastewater Treatment Plant have lowered the discharge of nutrients into the Potomac River and planting cover crops on Eastern Shore farms has lowered the amount of nutrients leaching into the earth and reduced nitrate concentrations in groundwater.

“In New Insights, we find the scientific evidence to support what we’ve said before: we are rebuilding nature’s resilience back into the Chesapeake Bay ecosystem, and the watershed can and will recover when our communities support clean local waters,” said Bay Program Director Nick DiPasquale in a media release.

But scientists have also noted that while we have improved water quality, our progress can be overwhelmed by intensified agriculture and unsustainable development, and our patience can be tested by the “lag-times” that delay the full benefits of restoration work.

“This report shows that long-term efforts to reduce pollution are working, but we need to remain patient and diligent in making sure we are putting the right practices in place at the right locations in Chesapeake Bay watershed,” said UMCES President Donald Boesch in a media release. “Science has and will continue to play a critical role informing us about what is working and what still needs to be done.”

UMCES Vice President for Science Applications Bill Dennison echoed Boesch’s support for patience and persistence, but added a third P to the list: perspiration. “We’ve got to do more to maintain the health of this magnificent Chesapeake Bay,” he said.

“We’ve learned that we can fix the Bay,” Dennison continued. “We can see this progress… and it’s not going to be hopeless. In fact, it’s quite hopeful. This report makes a good case for optimism about the Chesapeake Bay.”

You can view an Executive Summary of the report here. Learn more.



Dec
03
2013

Bay Barometer: Chesapeake faces challenges from pollution, development

The Chesapeake Bay Program’s latest look at watershed health reflects the reality of an impaired Bay, where population growth and pollution could threaten stable blue crab, striped bass and shad populations.

Released today, Bay Barometer: Health and Restoration in the Chesapeake Bay Watershed collects and summarizes the Bay Program’s most recent data on water quality, pollution loads and other “indicators” of Bay health, from ecological markers like underwater grass abundance to measures of progress toward restoration goals.

According to the report, more than half of the watershed’s freshwater streams are in poor condition, almost three-quarters of the Bay’s tidal waters are impaired by chemical contaminants and just 29 percent of the Bay has attained water-quality standards.

But an absence of rapid improvement in Bay health is not an indication that our restoration efforts are ineffective. Instead, it is an indication that lag-times are at play. Knowing that we will have to wait before we see visible improvements in water quality gives officials hope that the work done in 2012—like the 285 miles of forest buffers planted along waterways, the 2,231 acres of wetlands established on agricultural lands or the 34 miles of streams reopened to fish passage—will lead to results in the watershed. In fact, long-term trends indicate nutrient levels in Bay tributaries are improving, with most showing lower levels of nitrogen and phosphorous.

“Bay Program partners have made significant strides in moving us ever closer to a healthy, restored Bay watershed,” said Bay Program Director Nick DiPasquale in a media release. “We will have to exercise persistence and patience as the actions we take to rebuild balance and resilience… into this complex ecosystem… show up in the data from our monitoring networks.”

Learn more.



Nov
12
2013

Groundwater pushes nitrogen into Bay, delays effects of restoration

Slow-moving groundwater on the Delmarva Peninsula could push excess nutrients into the Chesapeake Bay even after we have lowered the amount of nitrogen and phosphorous we put onto the land.

Image courtesy yorgak/Flickr

According to new research from the U.S. Geological Survey (USGS), most of Delmarva is affected by the slow movement of nutrients from the land into the water. A USGS model developed to track the movement of nitrogen through the region showed that groundwater—and the pollutants it can contain—takes an average of 20 to 40 years to flow through the peninsula’s porous aquifers into rivers and streams. In some parts of Delmarva, the groundwater that is now flowing into local waterways contains nitrogen linked to fertilizer used three decades ago.

The slow flow of nitrogen-laden groundwater into the Bay could affect efforts to restore the watershed, lengthening the “lag-time” between the adoption of a conservation practice and the effect of that practice on a particular waterway. In other words, it could take days or even decades for today's management actions to produce positive water quality results.

“This new understanding of how groundwater affects water-quality restoration in the Chesapeake Bay will help sharpen our focus as many agencies, organizations and individuals work together to improve conditions for fish and wildlife,” said Lori Caramanian, Department of the Interior Deputy Assistant Secretary for Water and Science, in a media release.

While these findings seem to contradict the value of our restoration work, the study in fact indicates that pollution-reducing practices put in place over the past decade have begun to work. The study also confirms that rigorous steps taken to reduce nutrients on the land will lower the amount of nitrogen loading into streams in the future.

Learn more.



Oct
31
2013

Letter from Leadership: Lag-times call for patience in awaiting a restored Bay

How poor are they that have not patience! What wound did ever heal but by degrees?
William Shakespeare, Othello, Act II, Scene 3

Between fast food restaurants and speed-of-light cell phones, we live in a culture of instant gratification. But the environment around us doesn’t operate that way. Instead, it is slow to respond to changes—like the upsets or imbalances created by human activity.

Scientific evidence shows that many of the pollution-reducing practices we are placing on the ground now may take years to show visible improvements in water quality. One reason? Pollutants can be persistent. French and Canadian researchers, for instance, tracked the movement of fertilizer through a plot of land over the course of three decades. While more than half of the fertilizer applied to the land in 1982 was absorbed by agricultural crops like wheat and sugar beet, 12 to 15 percent remained in the soil. The researchers predicted it would take an additional 50 years before the fertilizer fully disappeared from the environment.

Much of the farmland in the Chesapeake Bay watershed sits over groundwater, now contaminated with high levels of nitrates following years of fertilizer applications above ground. Work by the U.S. Geological Survey (USGS) has shown that it will take a decade for this nitrogen-laden groundwater to flow into rivers, streams and the Bay. On the Delmarva Peninsula, where deeper, sandy aquifers underlie the Coastal Plain, this so-called “lag-time” could take 20 to 40 years.

So what implications could lag-times have for the Bay restoration effort? Last year, the Chesapeake Bay Program’s Scientific and Technical Advisory Committee (STAC) released a report about the lag-time phenomenon. The team of experts concluded that lag-times will affect public perception of our progress toward meeting the pollution diet set forth by the Chesapeake Bay Total Maximum Daily Load (TMDL).

The TMDL requires the six Bay states and the District of Columbia to implement their proposed pollution-reduction measures by 2025. There may be an expectation on the part of the general public and our elected officials that once these measures are fully implemented, the Bay will have met its water quality goals. But now we know that it may take some time before we can make that claim. As 2025 approaches, we must remind the public that lag-times exist and ask for their patience in seeing a healthy Bay. Because through patience—and vigilance—the Bay will be restored. 

Note: The opinions expressed above are those of the author and do not necessarily reflect U.S. EPA policy, endorsement, or action.

Nick DiPasquale's avatar
About Nick DiPasquale - Nick has nearly 30 years of public policy and environmental management experience in both the public and private sectors. He previously served as Deputy Secretary in the Pennsylvania Department of Environmental Protection, Director of the Environmental Management Center for the Brandywine Conservancy in Chadds Ford, Pennsylvania and as Secretary of the Delaware Department of Natural Resources and Environmental Control.



Sep
25
2013

Lag-times call for patience in awaiting restoration results

Cover crops, sediment ponds and streamside trees and shrubs: each of these conservation practices will slow the flow of pollutants into the Chesapeake Bay. But each will take different amounts of time to produce water quality results, according to a panel of experts convened by the Chesapeake Bay Program.

Image courtesy Uncle Kick-Kick/Flickr

In a report released this month, the Bay Program’s Scientific and Technical Advisory Committee (STAC) notes that the impacts of changes in land use and pollution loads into rivers and streams will not always be immediately reflected in changes to water quality. In fact, these so-called “lag-times”—or the stretch of time between the adoption of a conservation practice and the effect of that practice on a particular waterway—could call for patience in awaiting visible results from our restoration work.

Lag times are a natural part of our environment: as rainwater soaks into the ground, it can move nitrogen through the soil, and strong storms can pick up sediment and deposit it elsewhere. Because conditions in the Bay are a result of current human activities and a legacy of activities from the past, it makes sense that management actions taken now could take days or even decades to produce positive results. In fact, scientists know that some practices—in particular, those that take place close to rivers and streams—can produce results faster than others.

But according to STAC, this doesn’t mean that we should scale back on watershed restoration. Instead, an understanding of lag-times improves our understanding of how the ecosystem works, and reminds us to be “patiently realistic about the time-scale for observing results.”

Learn more about lag-times and the Chesapeake Bay.



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