From the Maryland Department of the Environment:
Governor Martin O’Malley and Col. Dave Anderson, Commander of the U.S. Army Corps of Engineers, Baltimore District, today announced the launch of a study of strategies to protect the Chesapeake Bay from sediment and other pollutants from the lower Susquehanna River watershed, including those that accumulate behind the Conowingo Dam.
“We must do everything we can to protect the health of our Bay for our children and theirs,” said Governor O’Malley. “We are pleased to announce this series of studies to assess how a strong storm could affect our ability to protect the Bay from sediment and other pollutants. Tropical Storm Lee provided a vivid demonstration of the need to take steps to head off what could be a catastrophic event causing immediate and enormous damage to our restoration processes. The time to address this threat is now.”
The Lower Susquehanna River Watershed Assessment – Phase I will provide critical information to address concerns that a strong storm could scour vast amounts of the Susquehanna sediments and negate progress made in restoring the Chesapeake Bay.
The storm surge from Tropical Storm Lee earlier this month delivered an estimated 4 million tons of scoured sediment from the lower Susquehanna River watershed to the Bay, along with excess nutrients, nitrogen and phosphorus. The last high-flow event of this magnitude was Tropical Storm Agnes in 1972, which devastated the Bay by smothering underwater grasses and oyster beds.
Experts from the Maryland Departments of the Environment and Natural Resources, the Corps, the Susquehanna River Basin Commission, and the Nature Conservancy will team up for the new study. The study will evaluate the millions of tons of lower Susquehanna River sediment stored behind the Conowingo Dam and three other hydroelectric dams on the Susquehanna River. It will also assess strategies to manage and reduce sediment from the lower Susquehanna mainstem watershed. The watershed implementation plans for Maryland and Pennsylvania that are being developed to meet the Chesapeake Bay “pollution diet” will be integrated into the assessment.
Experts from the Corps’ Baltimore District and their Engineer Research and Development Center will use cutting-edge modeling techniques to simulate sediment transport and deposition through the river and Bay system, with the goal of evaluating structural and nonstructural strategies for sediment management.
“The Chesapeake Bay is one of the world’s most important estuaries. This study demonstrates the commitment of our partnership to develop coordinated solutions across multiple stakeholders that will help protect the Bay,” said Colonel Anderson.
U.S. Environmental Protection Agency water quality standards established for Chesapeake Bay assume that upstream storage in the Susquehanna watershed will continue to trap substantial amounts of sediment and pollutants through at least 2025. If that is not possible, the States in the Susquehanna Basin (New York, Pennsylvania, and Maryland) will be required to identify and implement other pollution control measures to meet the EPA-imposed standards.
Of the dams on the Susquehanna River that are in the study area, only the Conowingo Dam has any remaining capacity for storing sediment. The Conowingo Dam, which is the closest of the dams to the entrance to the Chesapeake Bay, can trap about 2 million tons of sediment out of the approximately 3 million tons that reach its pool area yearly. But it is estimated that the reservoir’s capacity to store sediments will be reached in 15 to 20 years under current conditions. At that time, sediment and nutrient inputs to the Bay would increase dramatically, threatening efforts to improve Bay water quality and increase the health of aquatic life.
The assessment will develop broad, planning-level strategies and anticipated impacts and benefits to the Chesapeake Bay. While the study will not result in a single, recommended plan, it will provide essential information to be further evaluated by the States and federal government.
The assessment will cost $1.4 million over the three-year period. The $344,000 non-federal share of the project will be met in services provided by the Maryland Departments of the Environment and Natural Resources, the Susquehanna River Basin Commission and the Nature Conservancy.