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Living with the Bay’s Lag Time

DSC_0120We are becoming an increasingly impatient society, what with the Internet, portable computers, smart phones, Apps, and other instant communications.

Mother Nature, however, hasn’t logged on.

Case in point: Recent research by the U.S. Geological Survey reveals it can sometimes take decades for Chesapeake Bay restoration efforts to pay off in cleaner, healthier water in streams, rivers, and the Bay.

Certainly it’s understandable that after spending decades and billions of dollars on restoring the Bay, everyone in Bay country wants to see evidence of positive change. Right now.

And with some of the Bay cleanup efforts, we are seeing exactly that. Installing the latest nutrient-reduction technology at a municipal sewage treatment plant, for example, produces immediate results -- less nitrogen in discharges and therefore cleaner, healthier receiving streams and rivers.

Perhaps the poster child for this is the Potomac River below Washington, D.C. Over the past decade, Potomac FLS 072 the massive Blue Plains wastewater treatment plant in Washington has been upgraded with state-of-the-art nutrient removal. As a result, much of the nutrient-spawned algae that once chocked the Potomac below the plant has cleared, producing clearer water, lush beds of underwater grass, more fish, and more bald eagles, ospreys, and cormorants that eat them.

Potomac FLS 011Other clean water fixes, however, can take significantly longer to produce results, as the USGS research reveals. USGS scientists focused on how long it takes rain, snow, and other water falling on the Delmarva Peninsula to soak into the ground and make its way into Chesapeake Bay streams. The scientists used computer models to gauge the amount and age of the nitrogen in the groundwater and when the nitrogen got into the water in the first place.

Excess nitrogen, of course, is among the Bay system’s most serious problems; stemming nitrogen pollution from all sources – farm and urban runoff, sewage treatment plant discharges, air emissions -- is a major focus of the regional Chesapeake Clean Water Blueprint to restore the Bay.

Basically, the USGS researchers found that the nitrogen-bearing groundwater now seeping into Bay Marsh at Kiptopeke2waters from the Delmarva Peninsula ranges in age from less than a year to hundreds of years old. The median age is between 20 and 40 years. The variability is due to differing geology.

“These groundwater age distributions are markedly older than previously estimated for areas west and north of the Bay, which has a median age of 10 years,” USGS says. “The older ages occur because the porous, sandy aquifers on the Delmarva yield longer groundwater return times than the fractured-rock areas of the Bay watershed.”

And there is this: Because it can take decades for some groundwater to make it to the Bay, we may see increases in nitrogen seeping into the Bay in future years because of what was happening on the ground on the Delmarva Peninsula 30 or 40 years ago.

“In some areas of the Delmarva the groundwater currently discharging to streams is gradually transitioning to waters containing higher amounts of nitrate due to fertilizer used during the 1970s through the 1990s,” USGS says. “Similarly, the total amount of nitrogen in the groundwater is continuing to rise as a result of the slow groundwater response times.”

Talk about testing patience. Clearly nature isn’t buying society’s demands for instant gratification.

After planting photo with Barn (2)But that by no means suggests we should change course or slow Bay restoration efforts. We must continue to put in place the practices and programs that we know will reduce nitrogen and other pollution getting into groundwater, streams, rivers, and the Bay. For some practices, we will see the Bay respond fairly quickly, as scientists have noted. For others, the clean water payoff may be in years or decades to come.

But all such efforts are investments in the Bay, quality of life, the economy, and the future of our children and grandchildren.

For more about the USGS research, click here.

Chuck Epes

Chesapeake Bay Foundation


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This is interesting science that is slowly be released to others beyond the testing labs. Thanks. I do want to encourage all that I have seen a difference in the past when we all decide to work together at the pollution we can control and let the earth deal with the past!
The Northern Bay suffers from nitrogen laden runoff,not just from Pa., but our own flood ways and treatment plants. I have watched a severe declined in both the Bush and Gunpowder rivers. Previously b to c graded rivers down graded to dead zones this past summer. Reason: runoff and sewage treatment plant discharges exceeding EPA limits.
Solution: repair flood ways, and treatment plants!
We can do the things NOW, let the plant deal with the past, in most cases it able to if we can help

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