Revised Model Data Raises Concerns with TMDL Standards and WIP Requirements

Earlier this month, the state’s Chesapeake Bay TMDL Stakeholders Advisory Group (“SAG”) considered the effect of EPA’s revised model data on Virginia’s ability to effectively implement Phase II of the state’s Watershed Implementation Plan. While the revised data decreased Virginia’s basin-wide reduction target for nitrogen (from 53.42 million pounds per year to 52.46), it increased the target for phosphorus from 5.36 million pounds per year to 6.46 million. These changes come as the state and local governments, along with stakeholders, are trying to identify strategies to meet these goal reductions. A hard enough undertaking without a moving target.

The revised model data also updated land use to include more complete urban coverage and revised rates for nutrient management versus non-nutrient management applications of fertilizer. These changes raised questions and more than a few concerns as to how the revised model data was developed, but state officials indicated that they were unable to get a clear explanation from EPA as to how the methodology was derived.