An article in the May 2015 edition of the Chesapeake Bay Journal reported that according to recent figures released by the Bay Program, the Maryland region is likely to fail to meet its 2017 pollution reduction goals for nitrogen, phosphorus, and sediment under the federally mandated Chesapeake Bay Total Maximum Daily Load. The article noted that the main cause of the predicted nitrogen shortfall is Pennsylvania, which has failed to adequately address its nitrogen sources. From the article:
While overall progress is being made, the figures show no substantial increase in the rate of nitrogen reductions compared with the years immediately preceding the establishment of the pollution diet. In part, that’s because new data show some nitrogen loads, primarily from agriculture, had been underestimated in the past.
As a result, it is increasingly unlikely that the region will meet its interim 2017 reduction goals for nitrogen — the nutrient primarily responsible for the Bay’s summertime dead zone.
The shortfall is driven in large part by Pennsylvania, which faces a huge gap, and where estimated nitrogen loads have actually increased slightly. Other states face problems, though they are smaller in scale.
The sediment goal is also far off the pace needed to meet the 2017 goal.
And, the same is likely true for phosphorus. Although the goals are being met in computer model estimates, the actual loads reaching the Bay from tributaries show a different story, as monitoring by the U.S. Geological Survey shows increasing phosphorus loads from six of the Bay’s nine river basins over the last decade. Therefore, officials believe the phosphorus estimates released in April will be adjusted in the future.
The article discussed the Pennsylvania nitrogen shortfall and its impact on the health of the Bay through the Susquehanna River.
But the data show that 23 million pounds of [a 29 million pound nitrogen gap] stems from Pennsylvania, where computer estimates actually show a slight increase in nitrogen pollution since 2009.
Put another way, Pennsylvania would need to achieve nearly four times as much of a nitrogen reduction as the rest of the watershed combined in the next three years to achieve the interim goal.
The Pennsylvania shortfall is especially problematic for Bay water quality. The Chesapeake is essentially an extension of the Susquehanna River which drains most of Pennsylvania’s portion of the watershed. (A small part of Pennsylvania is in the Potomac basin.)
The Susquehanna is both the Bay’s largest tributary, and its largest source of nitrogen. Pound for pound, nitrogen from the Susquehanna also has a greater impact on dissolved oxygen levels in the Upper Bay than it does from any other river. In fact, scientists each year can predict the size and duration of the Bay’s oxygen-starved summer dead zone based on springtime river flows and nitrogen loads from the Susquehanna.
That means if nitrogen reductions from the Susquehanna are not achieved, it is very difficult to offset them with greater reductions from other areas to meet Bay dissolved oxygen goals.
The article also analyzed the shortfalls in other states and also highlighted the potential underestimating of phosphorus runoff due to soil saturation on Maryland’s Eastern Shore. The United States Environmental Protection Agency will be releasing its own TMDL assessment at the end of May.