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Criticisms of Chesapeake Bay Models Are Off Base

In his October 22nd essay entitled Logic and Passion and the Chesapeake Bay,Dr. Schnare does a disservice to readers by ignoring the world-renowned science and extensive monitoring behind models used in Chesapeake Bay restoration decision making.

We encourage Dr. Schnare to put down his Jane Austen novel and pick up the latest in a long series of independent scientific peer review reports on the full suite of Chesapeake Bay models.  And on this account we agree with the author—“Sounds dreadfully dusty and dry”—but very important when one wants to accurately describe the work of others.

Models are a tool for generating information and insights into managers’ what if questions for understanding the vast complexities of many sources of pollutants across the six-state Bay watershed, and for quantifying what actions are needed to ultimately achieve the states’ Chesapeake Bay water quality standards.

Many of the models being used in making Bay water quality restoration decisionsthe air deposition model, population land change model, Bay watershed model, Bay tidal water quality and sediment transport model, and the Bay oyster and menhaden filter feeder models—are in their 3rd, 4th or 5th generation of development and scientific improvement since the early 1980s.  Each has been independently reviewed by a panel of scientists with nationally recognized expertise. Each is approved by the state and federal Chesapeake Bay Program partners prior to management application. But these modelsare still just tools in the much larger and complex decision making arena of Chesapeake Bay restoration.

Though these models are based on hundreds of published works of scientific research, calibrated and verified based on decades of monitoring at hundreds of locations across the watershed and the Bay’s tidal waters, generating literally millions of individual data points, they are only as good as the science and data that goes into their development and application.

Thus, we do agree on one factwe (that being all the watershed states, USDA, EPA, our conservation districts and farmers) would benefit from a more complete accounting of the conservation practices put on the ground by our producers. It is a component of information that weall share a responsibility for filling. However, like water quality monitoring and measuring pollutant loads from wastewater treatment plants, we must have a system in place to not only report but verify the full implementation of such conservation practices. Just claiming widespread implementation does not lead to better decisions, from the field scale on up, without verification.

The model of focus within Dr. Schnare’s essay is the Bay watershed modelthe complex accounting tool that considers past and present land uses, pollution sources, human and animal populations, reported implementation of thousands of conservation practices and pollution control technologies, along with long term rainfall and other weather conditions and river flows. It is calibrated and verified to match up with actual measured stream and river water quality and flow conditions at hundreds of stations throughout the watershed across the past two decades.  Thus, the Bay watershed model provides a solid representation of the ambient water quality conditions in the Bay watershed’s streams and rivers, which, in turn, directly reflects what’s happening on the land, what’s discharged from point sources of pollution and what falls on the land and water surface from air deposition.

The more accurately weagain, referring to all of usmeasure, report and verify what’s happening on the land, what’s being discharged and what’s falling on the land/water, the better we are all positioned to understand relative contributions to pollution sources and how to proceed from here in restoring Bay water quality. For example, the six states, the District of Columbia and EPA are tracking pollutant discharges from 483 significant municipal and industrial wastewater facilities across the watershed. We are working together on the final stage of compiling similar data for almost 3,000 smaller municipal and industrial facilities.  Given the latest version of the Bay watershed model is segmented to provide information at the county scale and for the smaller underlying watersheds below the county scale, accurate load reporting and location of the discharge facilities is critical to ensuring that loads showing up in the streams and rivers water quality data are traced back to these land-based sources.

No where else in the country, for such a large interstate watershed and waterbody, is there tracking, reporting and crediting at the scale and detail that is carried out every year in the Chesapeake Bay watershed. We all have been positioned to make better decisions given the application of these tools, the worldclass science developed by our universities and colleges, and by the unprecedented monitoring networks across the Bay and its watershed generating data for the past decades.

But we can and must do better – better reporting, more verification of the full array of conservation practices and pollution technology controlsthat will help all us from conservation districts to state capitals make better decisions on restoring Bay water quality.

Finally, back to models. Someday soon the weatherman is going to predict rain. Now we may say that this prediction is just as good as their models representation of weather. We may say weather modelsdon’t have all the inputs perfectly represented. We may say that, and we’d be right. But the prudent among us will take our umbrellas.

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