Partners in the Chesapeake Bay watershed are familiar with the monumental challenges of a pandemic that crosses every border and threatens our health.
For 40 years, we have been working tirelessly to address an ecosystem-wide threat — a disease, if you will — caused by excess nitrogen, phosphorous and sediment harming the health of our rivers and streams, the Bay itself, much of the Chesapeake’s terrestrial and aquatic wildlife and human health.
A total maximum daily load or “pollution diet” now guides the restoration of the Bay and its watershed. The TMDL is the Chesapeake’s treatment plan. It is grounded in system-wide science and monitoring coordinated and enforced by the U.S. Environmental Protection Agency and implemented by the states and localities in the watershed. While partners have been successful on a number of fronts, we now face the most difficult stage of treatment.
The sources of pollution that plague the Chesapeake’s waterways are well-known: In addition to atmospheric deposition of nitrogen in the Bay, excess nitrogen, phosphorous and sediment flow in from wastewater, urban storm water runoff and farms.
Clean Water Act regulations largely address wastewater pollution and, to a lesser extent, stormwater runoff. Polluted runoff from agricultural landscapes, though, is mainly addressed through voluntary measures like agricultural best management practices, and this presents an entirely different challenge.
Determining the amount of pollution emitted from the end of a pipe (like wastewater) is relatively simple. It is much more difficult to determine the amount and source of pollution dispersed across wide areas, such as farms, lawns and parking lots.
Partners in the state-federal Chesapeake Bay Program use a suite of watershed modeling tools, including the Chesapeake Assessment Scenario Tool (CAST), to understand how nutrient and sediment pollution impacts the Bay and determine how best to restore and protect local waterways.
New innovations, including high resolution satellite imagery and land cover/land use mapping, enable us to estimate pollution loads with more detail than ever before and to prioritize and tailor restoration actions on individual tracts of land. Just as contact tracing and mapping are critical for fighting the COVID-19 pandemic, restoring the Chesapeake will depend on enhanced data collection and high-resolution geospatial analysis to show partners more precisely which conservation and restoration actions are most needed and where best to use them.
With these new tools, partners can better address nonpoint source pollution and revolutionize the cleanup by shifting it from effort-based to performance-based metrics.
The Bay watershed model currently credits the value of a pollution-reduction activity on farmland by watershed sub-basin. The model determines credits for best management practices in almost 2,000 sub-basins with an average size of 33 square miles. In practice, this means that a credit is based on the average performance of restoration practices in that location and the number of acres treated. But with higher resolution data, it is possible to estimate pollutant reduction opportunities of different BMPs specific to each parcel of land.
For example, it has been known for decades that forest buffers help to prevent nutrient and sediment pollution from entering local waterways. Now we are able to compare restoration opportunities across the landscape by rapidly mapping the agricultural land that drains to each potential buffer. This means that in the near future we may be able to differentiate the projects that filter the most pollution and accelerate Bay restoration with performance-based crediting of the best restoration projects.
Therefore, in the near future, the Bay watershed model could employ higher resolution geospatial data and change how BMPs are valued at the very local scale. Crediting BMPs at a finer scale means that the pollution reduction and the benefits to the local landscape are incorporated in the value of the credit.
The location of a BMP on an individual farm and within a local watershed can make a significant difference in water quality outcomes, and this new approach rewards farmers, municipalities and others for the full extent of water quality benefits they provide to our streams and rivers.
The implications of this new approach cannot be understated. To refer back to our medical analogy, this is like diagnosing each patient individually and sending the most effective medicine to the exact part of the body where it’s most needed.
The EPA and its Bay Program partners’ support for this work has been and continues to be critical to our collective impact on the Bay. By enhancing the accuracy and precision of the data input to the Bay watershed model, as well as how it credits the specific location of individual BMPs, we can optimize the entire restoration approach and meet our cleanup goals faster and at lower costs.
Rich Batiuk is the former associate director for science, analysis and implementation with the EPA Chesapeake Bay Program Office. Joel Dunn is the president and CEO of the Chesapeake Conservancy.
The views expressed by opinion columnists are not necessarily those of the Bay Journal.