As a scientist, I have worked over the past 40 years to identify the causes of the degradation of the Chesapeake Bay and to seek effective means to restore it. Thirty years ago, pollution by excessive amounts of nutrients was identified as the bay’s systemic problem. Although the nutrient pollution originates from numerous sources, the largest source is agriculture, coming from fertilizers not taken up by crops and from animal wastes.
In 1987, the bay states and the federal government agreed to substantially reduce this pollution. Deadlines for reduction goals were set for 2000 and then 2010; both times they were missed by a great deal. After the 2010 deadline passed, by prior agreement among the states and federal government and as required by the Clean Water Act, the Environmental Protection Agency developed what is commonly called a pollution diet that each state would have to achieve and stick to. A new deadline was set — 2025 — but all parties agreed that, this time around, there would be two-year milestones to verify progress.
The pollution diets for each state, county or river watershed are determined by estimating the pollution the bay can tolerate, quantifying all relevant pollution sources, and identifying strategies to lead to the desired load reduction. This requires computer models that bring together current scientific understanding, extensive data and choices by the states about preferred strategies. The models used by the Chesapeake Bay Program — the partnership of the Environmental Protection Agency, the District and the six states in the bay’s watershed — have been developed and refined over the past 30 years and subjected to peer review.
Nonetheless, interest groups and some political leaders have questioned the reliability of the models. Most notably, the American Farm Bureau Federation and several other national agribusiness organizations filed suit to stop the EPA from implementing the pollution diet, citing among their arguments the use of “unsuitable” computer models.
Many of these groups hired an experienced consulting firm, LimnoTech, to compare the pollution load estimates from the Chesapeake Bay Program model with those from a new model developed by the U.S. Department of Agriculture to quantify the effects of conservation practices applied to cultivated cropland. Based on the differences in results, LimnoTech called for a “timeout” in implementing the pollution diet until the differences could be reconciled and a “correct” model produced. This criticism further alienated farmers from the pollution diet, and some in Congress used it to justify efforts to withhold funds for the plan’s implementation and even to eliminate the EPA’s authority to implement the Clean Water Act.
The Chesapeake Bay Program asked its Scientific and Technical Advisory Committee to review these criticisms. Released last week, the review by a panel of independent experts concluded in unusually scathing language that the LimnoTech analyses have poor scientific merit, use false criteria for judging the suitability of the Chesapeake Bay Program models for setting the diet, and commit errors in interpretation of model results.
When these errors are corrected, the two models produce much more similar results. Moreover, the two approaches fully agree that more effective and widely implemented management practices on cropland are required. In the end, the independent experts concluded that the LimnoTech report simply does not provide sufficient evidence to suspend implementation of the pollution diet.
As with climate change, the seeding of scientific doubt may be used to delay action in addressing the problem. But in this instance, we know beyond reasonable doubt the road we need to take to restore the Chesapeake Bay’s water quality. Further, we understand that arriving at this destination by the deadline requires walking at a faster pace, not only with agriculture but with the other nutrient-pollution sources: waste and stormwater discharges and fallout from air pollution. Now is not the time to take a timeout to figure out precisely — even if we could — whether the destination lies 10 miles or 11 miles ahead. We will know better when we get closer, and in 2017 there will be a recalibration of just how close we are. Meanwhile, we need not only to keep walking but to pick up the pace.
The writer is president of the University of Maryland Center for Environmental Science.