Chesapeake Bay Program Releases 2015 Watershed Model Estimates

Evan Isaacson

April 19, 2016

Yesterday, the Chesapeake Bay Program released its latest estimate of nutrient and sediment pollution in the Bay watershed. The annual model run of the program's Watershed Model shows that the estimated nitrogen, phosphorus, and sediment loads decreased by three percent, three percent, and four percent, respectively, compared to 2014 levels. These are important improvements, but much work lies ahead to improve water quality in the Bay and boost the fisheries, wildlife, and recreational activities it supports.

The estimated decrease in nitrogen loads of nearly 7 million pounds brings the Chesapeake Bay a bit closer to the 2017 interim target under the restoration plan known as the Chesapeake Bay Total Maximum Daily Load (Bay TMDL). However, the watershed as a whole – including the six Bay states of Delaware, Maryland, New York, Pennsylvania, Virginia, and West Virginia, plus the District of Columbia – remains significantly off track.

The latest annual data release provides both good news, as well as some more caveats and concerns. Starting with the more positive news, this is the first time that all seven jurisdictions have reported an annual decrease in nitrogen loads over prior-year levels. These decreases range from very slight in Delaware as well as in Virginia on a percentage basis, to substantial reductions in Pennsylvania (on an absolute basis) and the District of Columbia (percentage basis). Not every simulated reduction in the program's model is the result of real pollution reductions, however. A sizable margin of error should be factored in to any reading of model results, and some changes could reflect a change in assumptions or other model inputs.

Also on the positive side, Virginia became the second jurisdiction, after the District, to cross the 2017 "finish line" according to the model, with the Commonwealth achieving 100.4 percent of its nitrogen reduction goal. It should be noted that pollution loads may increase from year to year, meaning the Commonwealth could fall below that mark in 2016.

The model also estimates a significant decrease of over 2 million pounds of nitrogen from Pennsylvania's agriculture sector, an encouraging sign. As noted in our February report, Countdown to 2017, Pennsylvania contributes more nitrogen pollution to the Bay than any other jurisdiction (and more than several jurisdictions combined), and its failure to reduce agricultural pollution was among the biggest reasons that efforts to restore the Bay under the TMDL remain in jeopardy.

Finally, the latest model release shows that, once again, investments made by the seven Bay jurisdictions to address nutrient pollution from wastewater treatment plants continue to pay off. According to this latest data, the wastewater sector more than achieved its share of reductions as of 2014, and yesterday's model run shows another eight percent reduction of nitrogen from wastewater over the last year. The result? The sector has achieved more than 165 percent of its 2017 goal. With many more wastewater treatment plant upgrades in the queue – especially in Maryland – it is likely that the sector will meet the 2025 pollution reduction goal many years ahead of schedule.

Despite these encouraging signs, the latest model run also demonstrates that the story remains much the same for restoring the Chesapeake Bay. With only two more years remaining before the interim deadline, overall pollution reduction efforts have achieved less than half of what is needed to meet the 2017 target. And the progress that has been made under the Bay TMDL, as is the case for most TMDLs, is largely the result of efforts to simply ratchet down point-source pollution from sources like wastewater facilities under the traditional regulatory authority of the National Pollutant Discharge Elimination System (NPDES) program. For any TMDL to succeed, it must lead to widespread pollution reductions from all responsible sectors, point and nonpoint (or "runoff") sources alike.

Even jurisdictions like Virginia and the District of Columbia, which reached their overall 2017 goal years early, fell far short of meeting some individual pollutant reduction goals mostly tied to nonpoint source and runoff pollution. For example, nitrogen pollution from urban runoff is barely below 2009 baseline levels in the District and far above baseline in Virginia. The situation for urban nitrogen runoff is so bad around the watershed that the District's meager 0.5 percent reduction nearly leads all Bay jurisdictions in that category. Pennsylvania is the only other jurisdiction that has been able to very slightly reduce urban nitrogen pollution since 2009.

But the bottom line for the Bay continues to be that nitrogen pollution from agricultural runoff is far greater than target levels. Agriculture is the source of nearly half of the nitrogen pollution in the Bay watershed, with nearly 60 percent of agricultural nitrogen loads coming from Pennsylvania. Even though the state is estimated to have reduced nitrogen loading to the Bay by more than 2 million pounds in 2015, its agricultural sector has only made about one-fifth of the progress toward its 2017 goal, with little hope of closing this huge gap in just two years.

Pennsylvania announced a "reboot" plan earlier this year to restart the Commonwealth's efforts under the Bay TMDL, a necessary move after EPA temporarily withheld almost $3 million in federal funds. And while the Pennsylvania Department of Environmental Protection has created a new Chesapeake Bay Office and announced plans to hire new inspectors and establish a "culture of compliance" with environmental laws, the bulk of the work under the plan has not yet begun. Indeed, the Commonwealth hasn't even announced how it plans to pay for the millions of dollars in clean water investments needed to make any reboot an effective reality.

The Bay Program Watershed Model is, by definition, only a representation of reality, but it is a necessary complement to ongoing water quality monitoring and sampling of actual water pollution levels. Monitoring, too, can misrepresent progress due to annual fluctuations in weather and lag times between the creation of a pollution reduction method and its effects.

Like it or not, the model is the official "scorecard" by which we assess the efforts of the Bay jurisdictions in implementing the Bay TMDL. With time running out before we reach the end of this first period of the program, we've seen some important progress, but the overall score is still not looking that great.

Read More by Evan Isaacson
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