The Agricultural Nutrient Policy Council, made up of state and national groups including the Virginia Grain Producers Association, has released a report that presents serious inconsistencies and gaps in the data used by the Environmental Protection Agency (EPA) to set pollution limits for the Chesapeake Bay.

Commissioned by a coalition of agricultural groups, the report contrasts EPA’s estimate of the Bay’s “nutrient diet” with those of the Agriculture Department, which are much more favorable to farmers. It asks EPA to not issue a rule setting the Bay’s “pollution loads” until the inconsistencies can be reconciled.

The report was prepared by LimnoTech, one of the nation’s leading water sciences and environmental engineering consulting firms. It compared EPA’s Total Maximum Daily Loads with those in the draft U.S. Department of Agriculture (USDA) report Assessment of the Effects of Conservation Practices on Cultivated Cropland in the Chesapeake Bay Region.  

The key concerns outlined in the report are:

1.) EPA should not finalize the TMDL until USDA and EPA reconcile differences in estimates.

2.) Differences in land use are substantial.

3.) Differences in hydrology and their implications need to be investigated.

4.) USDA and EPA model assumptions regarding cropland differ dramatically.

5.) Major differences in the model frameworks and their implications need to be understood.

6.) The model results are substantially different and raise significant concerns that should be investigated and resolved before the TMDL is finalized.

The report calls for a “timeout” on the Bay TMDL to make sure EPA does not push the use of its pollutant estimation model beyond its original design.

“USDA estimates that seven percent of cropped acres are under conventional-tillage, five percent of cropped acres have a level of tillage between conservation-tillage and conventional-tillage, and 88 percent of cropped acres are under conservation-tillage (mulch-till or no-till) practices…

EPA estimates that 50 percent of cropped acres are under conventional-tillage and 50 percent are under conservation practices.

In general, the cultivated cropland conservation practices incorporated in USDA’s model framework are documented and statistically valid in sufficient detail to allow a general understanding of practices accounted for in the modeling, the assumptions made regarding specific conservation practices, and the level of implementation. A similar level of detail and documentation is not, however, available for the EPA model framework.”