Climate Change, Growth & Conowingo Dam Challenge 2025 Bay Restoration Goals

Bay Journal article (2018-01-24) explored the three biggest challenges facing Maryland in meeting the 2025 nutrient and sediment reduction goals under the Chesapeake Bay Total Maximum Daily Load: (1) growth; (2) climate change; and (3) the Conowingo Dam. A draft number representing the combined nitrogen generated by these three factors could offset much of the existing nitrogen gains made since 2010. While these factors pose hurdles for all Bay watershed states, Pennsylvania faces the largest shortfall. The article noted that the Bay Program will likely have states address these factors as part of their Phase III Watershed Implementation Plans (WIPs) but not necessarily require them to fully implement them by 2025.

Conowingo Dam

The Conowingo Dam has lost its ability to trap nutrients that flow down the Susquehanna River. Maryland Governor Larry Hogan is reviewing proposals to dredge some of the sediment in the Dam’s reservoir, restoring some of its nutrient capturing potential. However, that plan is still in its preliminary stages.

State officials at the December [Bay Commission] meeting agreed to develop a plan for additional nutrient reductions to offset the impact of Conowingo, but they did not commit to fully implementing it by 2025.

Climate Change

The article noted that climate change posed a significant challenge to Bay restoration efforts as the original pollution reduction targets were based on steady climate conditions from the 1990s to 2025. However, state officials were unprepared for climate change numbers added an estimated 4% more nitrogen to the target loads. The changing precipitation rates could also reduce the effectiveness of some stormwater best management practices.

After extensive debate, officials agreed that their watershed implementation plans would generally describe how the states will address nutrient loads from climate change, but delayed quantifying the needed amount of reductions until 2021.

Delaying the inclusion of numeric goals was intended to give scientists more time to refine their estimates and to identify which nutrient control practices are most likely to withstand changing climate conditions.

Growth

The article stated that growth is projected to add an additional 4 million pounds of nitrogen and 154,000 pounds of phosphorus to the Bay by 2025.

[F]orecasts of growth will be incorporated into the nutrient reduction goals given to each state, which will now account for growth upfront when they write new watershed implementation plans.

The article noted that the growth forecasts will be updated every two years.