Climate Change Poses New Nitrogen, Phosphorus Challenges to Bay Restoration

Bay Journal article (2019-01-30) examined how climate change will affect ongoing Chesapeake Bay restoration efforts. The article stated that additional nitrogen and phosphorus reduction targets will be added to the Bay Total Maximum Daily Load (TMDL) in 2021 to address the additional precipitation and storm severity predicted due to climate change.

From the article:

When it comes to runoff, “flow is fate,” said Lewis Linker, modeling coordinator with the state-federal Bay Program partnership. More rain moves more nitrogen off the landscape and into the Bay, while heavier storms dislodge sediment particles — and the phosphorus that binds to them — and moves them downstream as well.

Prior Bay model programs, which are used to set TMDL nutrient targets, did not account for climate change and thus the current targets that states and local governments are working towards lack the additional loading caused by climate change. Currently, Bay states must include written descriptions in their Phase III Watershed Implementation Plans (WIPs) due in April, 2019, detailing how they will address climate change in their restoration efforts. The Bay Program is working on updating the model and will have revised nitrogen and phosphorus goals in 2021. The article noted that rough projections estimate an additional 9.1 million pounds of nitrogen (19% beyond current reduction targets) and 490,000 pounds of phosphorus (73% beyond current reduction targets) will need to be addressed before the final 2025 deadline.

The article acknowledged that reaching the new goals will be a daunting task:

Mark Bennett, director to the U.S. Geological Survey’s West Virginia and Virginia Water Science Center and co-chair of the Bay Program’s Climate Resiliency Workgroup, cautioned that it will be a daunting task to re-examine the effectiveness of the dozens of best management practices implemented in the region to meet Bay goals under future climate scenarios.

The article discussed specific challenges posed to the agriculture and stormwater sectors, including managing increased rainfall, temperatures, runoff, and land erosion.

The article also described how the District of Columbia has agreed to be a test case and has gone beyond written descriptions in its WIP. The District has agreed to reduce an additional 6,000 pounds of nitrogen and 1,000 pounds of phosphorus as part of its current obligations. The District is heavily focusing on projects with environmental co-benefits, including flood reduction and reducing the “urban heat island” effect.