If cleaning up the Bay depended only on nutrient control practices that have been used in the past, the restoration would be difficult, if not impossible. Fortunately, many nutrient control techniques and new technologies make the restoration well within the realm of possibility, according to a report last year by the Bay Program’s Scientific and Technical Advisory Committee.
The “Chesapeake Futures” report cautioned against “blind faith that inventions around the corner will solve all of our problems.” After all, a healthy ecosystem requires more than just nutrient reductions—it also requires land development, efforts to maintain vanishing tidal marshes, the restoration of lost grass beds, improved fisheries management and other non-nutrient actions.
But from a nutrient perspective, it said that a more widespread application of proven control techniques, as well as new technologies on the horizon, can help rein in the Bay’s nitrogen and phosphorus problem.
For example, the incorporation of biological nutrient control technologies at wastewater treatment plants has yielded some of the largest nitrogen reductions within the watershed to date. Yet many plants still do not use nutrient control technology, and few use state-of-the-art techniques that can achieve additional reductions for both nitrogen and phosphorus.
New septic technologies are able to reduce the amount of nitrogen reaching the groundwater from septic systems by about 50 percent. Because of retrofit costs, these may not be realistic for existing systems, but could be used on new installations.
In agriculture, the widespread use of cover crops, such as grasses or clover, can absorb excess nitrogen left in the fields after crops are harvested in the fall. Such plantings are hindered by the lack of ongoing support for programs that pay for planting cover crops, which increase expenses but do not provide income for farmers. If those programs were supported, they would yield large nutrient benefits.
Fertilizers are typically spread on the surface where they can run off the land, but new techniques to allow the subsurface application of synthetic fertilizers and animal manure can reduce nitrogen losses by about 20 percent, and phosphorus losses by 30 percent while also greatly reducing volatilization of ammonia into the atmosphere. That would also place the nutrients in the root zone where the plants can more easily use them.
Widespread use of this technology is hampered by farmer worries that reduced application rates would reduce yields, and the lack of incentive for fertilizer dealers to promote this technology. Nonetheless, it holds considerable promise for the future.
New techniques to process animal wastes are under development that would allow some to be repackaged and sold as fertilizers or burned as fuel. Animal wastes may eventually be treated with techniques that remove nutrients, similar to human wastes, although such processes are expensive for agricultural use today. Research on altering, and optimizing, the diets of farm animals can lead to feeding programs that reduce the amount of nutrients in their wastes.
Continued implementation of Clean Air Act regulations can eventually reduce nitrogen loadings from the air by 13 percent, but that requires controlling the increase in vehicle travel by successfully promoting mass transit and telecommunications as alternatives to road transportation. The Implementation of further available technologies to reduce nitrogen oxide emissions could result in a potential reduction of 27 percent.
Advances in alternative fuels, including the development of fuel cell technologies, would eventually reduce atmospheric deposition from vehicles by 70 percent. Improvements in animal waste management will eventually begin reducing ammonia emissions from agriculture.
In the urban landscape, a more aggressive implementation of existing storm water management technologies, as well as the use of emerging technologies which emphasize allowing rainwater to infiltrate into the ground rather than diverting it to streams, could reduce nitrogen from urban areas by 30 percent and phosphorus by 45 percent.
If all “feasible alternatives” were implemented, nitrogen loadings to the Bay would decrease by 143 million pounds from 2000 levels—surpassing the Bay Program’s cleanup goal, according to the report. Total phosphorus loads would decrease by 10 million pounds, achieving the Bay Program goal.
One important caveat: the Futures report estimates were for achieving improvements over 30 years—not a single decade.
Copies of “Chesapeake Futures” are available on the Scientific and Technical Advisory Committee’s web site, www.chesapeake.org/stac