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Story February 21, 2014

Volkswagens and Cadillacs: Restoring the Chesapeake Bay

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With support from Pulitzer Center grantees, William & Mary students explore issues from high HIV...

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U.S. Navy sailors pick up trash on the shore of the Chesapeake Bay during Clean Up the Bay Day. Image by Craig P. Strawser / U.S. Navy. United States, 2008.

Every day that David Black works the land in Southeast Virginia, he furthers a long tradition. Not only is he following in the footsteps of several generations of Black family members, but he is also farming land that has been in constant agricultural production for over 300 years.

Unsurprisingly, much has changed in the past several hundred years. The expansion of agriculture and human settlement in the Chesapeake Bay watershed has led to a decline in the health of the bay. In response to this continual decline, stakeholders from around the region have spent much of the last half-century attempting to reverse the trends and return the bay back to its former glory: to have the bay look, feel and be as it was when colonists started farming the land centuries ago.

Black's farming operation is anything but three centuries old. He has been at the forefront of melding economic success with environmental stewardship. As part of his stewardship, Black, like all farmers in Virginia, is required by law to cede any part of his land adjacent to perennial water source (i.e. within 35 to 100 feet from the bank of the stream) to vegetative buffers.

According to a 2010 Environmental Protection Agency (EPA) report, agricultural runoff is "responsible for approximately 43 percent of the N[itrogen], approximately 45 percent of the P[hosphorous] and approximately 60 percent of the sediment loads." Agricultural runoff occurs when rainfall is unable to be absorbed into the ground. Instead, the water accumulates and begins following elevation downhill, picking up whatever is in its path. In agricultural settings, this includes nutrients used in fertilizer like nitrogen and phosphorous, as well as any sediments. Should the runoff eventually reach a stream, these passengers in the runoff begin an even longer ride — one that could potentially end in the Chesapeake Bay itself.

While these nutrients and sediments are essential elements of agricultural production, in sufficient quantities they impair water quality and increase the likelihood of "dead zones" — low oxygen environments created by excessive algae formation. As Randy Chambers of the Keck Environmental Lab explains, "rainfall generates runoff, and the runoff carries the nutrients, and the nutrients stimulate the algal blooms. So the dead zone is directly related to the size of the runoff that we get."

Vegetative buffers, usually some combination of grasses and trees, are designed to mitigate the impact of agricultural runoff by slowing it down and trapping its potentially harmful passengers. A series of Virginia Polytechnic Institute and State University reviews found that in controlled settings, vegetative buffers are effective at preventing high percentages of nutrients and sediments from entering the adjacent water source. A more recent EPA meta-analysis supported these results.

As a result, vegetative buffers, or riparian buffers as they are also called, have been designated a "best management practice" for reducing the negative impact of agriculture on the Chesapeake Bay by the Chesapeake Bay Commission. A Virginia Department of Environmental Quality (DEQ) program manager called them "one of the best practices" we have to improve water quality. Agencies like the U.S. Department of Agriculture (USDA) and Virginia's Department of Conservation and Recreation (DCR) fund cost-shares to help farmers install these vegetative buffers. Non-profits organizations assist as well. The Chesapeake Bay Foundation (CBF) runs a "buffer bonus" program that adds additional private money into expanding acreage of buffers across the Chesapeake Bay watershed.

In short, a significant amount of time, money and effort go into promoting and implementing vegetative buffers on agricultural fields in Virginia and elsewhere in the Chesapeake Bay watershed. However, there is a catch. They don't actually work as advertised.

Understanding the "why" behind the ineffectiveness of vegetative buffers is a major research interest of Greg Hancock, a geologist at the College of William & Mary. He notes that many previous studies evaluating the effectiveness of riparian buffers occurred on small test plots in ideal conditions. In those cases, there is "the assumption is that you are taking this water and it's either infiltrating and moving beneath the riparian buffer, or if there is runoff it gets disseminated across the [buffer]." However, that is "not the way topography works." Instead, as water moves across a field it begins to concentrate and with enough concentrated flow, water can channel through a buffer rather than maintain a nice, even flow across the surface. In effect, a vast majority of the buffer's efficacy is negated, and the remaining area is insufficient to stem the flow.

To study the extent by which concentrated flow likely exists, Hancock and his team developed a method that utilizes high-resolution elevation data to estimate the amount of area on a field that drains to a particular point – evidence that concentrated flow is likely and therefore the buffer is unlikely to work as expected. In his study of 70 fields in the coastal plain of Virginia, he found that in every field he looked, "flow is being focused in a few places." For several of the study fields, he ground-verified his analysis, finding a high correlation between points of high drainage and deficiencies in the buffer.

Hancock is not the only stakeholder to notice the relative ineffectiveness of the buffers. For example, Gary Flory, a DEQ official working in the Shenandoah area, often spends his field time working with farmers in that region to repair and supplement buffers. Others, like Gary Moore of DCR, suggest that overall, buffers work as expected, but observe that "there is always a potential that some, and in certain situations, probably a majority, of the runoff is bypassing the groundwater treatment [of buffers]. I don't think it occurs all the time. I think it occurs with specific extreme [weather] events." As Hancock experienced when talking to stakeholders, they have "known about [the channelization of buffers] for years, but nobody has really bothered to address that." While overall there is at least tacit agreement about the problem, the extent and regularity of the problem is still up for grabs. The future work of Hancock and other researchers should shed light on these dimensions.

Over the last decade, approximately $15 million have been spent by Virginia farmers on implementing and maintaining riparian buffers in the Chesapeake Bay Watershed according to records publicly provided by the DCR. About half of that investment was funded by taxpayers through Virginia's Agricultural Cost Share (VACS) and Conservation Reserve Enhancement Program (CREP). Further expenditures have occurred through other programs such as the USDA's Environmental Quality Investment Program and Chesapeake Bay Watershed Initiative. Combined, these latter two programs have spent close to $1 million on vegetative buffers since 2011. In addition to this amount, there are also the significant costs assumed by the farmers who install buffers without engaging these programs as well as the implicit costs of lost productive land. Soon it becomes clear that a fair amount of money is being spent on what may very well be an ineffective practice.

Beyond the economic costs of buffer implementation, there are environmental costs to consider. For many observers, the health of the bay has not improved much over the last several decades. James Davis-Martin, a DEQ official said that "made very little progress over the last decade — the last three decades." Chambers provides a similar analysis, stating that while certain aquatic species have been responding to intensive management, the overall the size of the dead zone "does not seem to be getting much smaller despite increases in nutrient management." As Hancock notes, "[you] can't improve the health of the bay without improving how agriculture is working" and that the failure of the buffers could "provide an explanation to the fact that the Chesapeake Bay hasn't really gotten much better in the last 30 years."

Clearly, a disconnect exists. A growing body of research and anecdotal evidence suggest that buffers don't work as advertised, yet thousands of dollars are spent every year on these buffers. All the while, the Chesapeake Bay is not improving.

Through conversations with stakeholders, it appears the main issue is the failure of regional level policies to effectively address local conditions. According to Brian Noyes, the long-serving director of Colonial Soil and Water Conservation District, a potential source of conflict is over the changing definition of best management practices. In the past, best management practices were determined on a case-by-case basis depending on the needs of the individual farmer. However, today the "problem with best management practices is that they seen as an individual," and this in turn deemphasizes the benefits of systematic utilization. "[There is] no need for a Cadillac, if a Volkswagen will do." And a series of Volkswagens may very well be more effective than a single Cadillac.

The increasing modularity is partially due to the expansion of regional modeling logic to local scales. That is, the assumption is that what the model reflects is actually happening on the ground. Of course, this is not always the case. For example, when Moore and other Virginian stakeholders led the implementation of stream exclusion practices, their work was not reflected in the modeling. "[The modelers] would not accept our BMP that we know exists. We put it in. We went and reviewed it. We can see it on a spot check basis. And they would reject it and wouldn't give us any benefit."

While these issues were resolved after a considerable delay, the importance of these "benefits" is crucial. Not only does the Bay Program use the extent and location of best management practices to do scientific modeling, but these numbers also inform the responsibilities that various agencies and states have vis-a-vis the health of the Chesapeake Bay. However, when the "benefits" are incorrectly allocated, as may be the case for vegetative buffers, the resulting calculations are inevitably off. Some farmers and local officials like Black and Noyes have noticed this. As Noyes says, "if you're in this business long enough [you] understand all models are wrong, but some are useful."

As the case of Moore makes clear, change takes a long time. However, not all parties are standing still. Black, in a testament to his ingenuity, has been using a tall clover filter strip to line his buffers. The clovers are not only effective at managing runoff, but they have the added benefit of being a favorite food source for deer. In fact, the deer love the clover so much that they generally ignore his crops, and almost only eat the clover.

Beyond clever implementation schemes, Black and Noyes continue to promote no-till agriculture that was pioneered in the area over 20 years ago. As Noyes explains, no-till is about controlling the rain drop, and "if you can control that rain drop, you've got the problem licked." Meanwhile, Black has noticed "because of no-till, [there is] very little concentrated flow [like] we used to have." While Hancock's data suggest that concentrated flow may exist on no-till fields and tilled fields alike – so while comprehensive research is required, early anecdotal evidence is encouraging.

Long term, changes to the regulations determining buffer specifications are likely required. "With the existing way that we've required buffers to be implemented," Hancock argues, "I'm not sure there is a whole lot one could do to make things better." Ideas like allowing farmers to reclaim uphill land in exchange for expanding the buffer in a particular drainage area would inevitably require a revision of existing rules and regulations. In the meantime, Hancock was keen to stress that buffers "are certainly better than nothing." While the buffers might not work as advertised or as efficiently as desired, they are not completely ineffective. However, all else being equal, buffers will likely need to be reconceptualized and every day that they are not, restoring the Chespeake Bay to its state of 300 years ago will remain a pipe dream. As noted Chesapeake Bay commentator Howard Ernst said by email, "I think we will look back 30 years from now and remember 2013 as the good old days. It is quite sad, because if we cannot make progress here, where are we going to make improvements?"

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