This Week’s Headlines
‘A sense of urgency’ (Editorial)
(May 24, 2016) Amid recent reports of improved health of the Chesapeake Bay looms the threat of the Conowingo Dam’s inability to hold back much more sediment and nutrients from entering the Bay.
The final report of a $1.4 million Lower Susquehanna River Watershed Assessment released this spring by the Army Corp or Engineers confirmed that the Conowingo Dam reservoir and two dam reservoirs further upstream have essentially reached their capacity and are no longer capable of trapping sediment and associated nutrients over the long term.
The reservoirs at Conowingo, Holtwood and Safe Harbor dams were once looked at as aiding Bay improvement, trapping sediment and nutrients from reaching the estuary. However, that’s no longer the case.
Sediment normally catches much of the public attention to the dam, especially when large storm events or increased rainfall forces dam operators to open more gates and allow tons of sediment and a cadre of other debris to wash downstream.
But the report said sediments generally settle out of the water column within days or weeks and its the nutrients attached to the sediment that have a greater impact, fueling algal growth and contributing to lower dissolved oxygen levels affecting water quality and underwater ecosystems.
As a result, the Maryland Department of Environment, a partner in the Susquehanna assessment, said even with full implementation of Maryland’s federally-required bay cleanup plan, it will not be enough to achieve water quality standards in the three upper and mid-bay segments without strong actions from upstream states between 2017 and 2025.
The report’s findings not only accelerate the near-full reservoirs’ impact on the Bay past earlier estimates but could ultimately put more pressure on watersheds south of the Conowingo dam to increase nutrient reduction to offset what will come over it.
Computer modeling in the report shows reaching the water quality goals set forth by the Environmental Protection Agency’s Total Maximum Daily Load will require added reductions just from the Susquehanna River of 2.4 million pounds of nitrogen and 270,000 pounds of phosphorus.
Add to that Pennsylvania’s admitted shortfall in its progress in reaching its water quality goals without factoring in the dam’s impact and it’s a real recipe for disaster.
According to the Chesapeake Bay Program, Pennsylvania needs to increase its nutrient reduction more than four times its current rate to meet the TMDL’s goal for 2025.
If those reductions need to come from other watersheds in the Bay area to offset Pennsylvania’s impact, the job becomes much tougher, the report’s modeling said, as amounts go up to 4.4 million pounds of nitrogen and 410,000 pounds of phosphorus.
“This justifies a sense of urgency;” said Chip McLeod, an attorney representing the Clean Chesapeake Coalition, a group of Maryland counties advocating for more attention to the Conowingo Dam’s reservoir, speaking about the report “as our efforts and expenditures in Maryland to improve Bay water quality are otherwise being inundated by upstream pollution.”
Solutions aren’t easy or cheap.
The Lower Susquehanna assessment said dredging to keep up with what nutrients would need to be trapped would cost between $15 million and $270 million annually and further added that the benefits of dredging to the watershed ecosystem are “minimal and short-lived.”
Excelon, the energy company looking to relicense the dam for power generation has contributed $3.5 million toward additional studies on how what’s behind the dam might impact the Bay and reports from them are expected before the end of this year.
Meanwhile, the University of Maryland Center for Environmental Science last week issued its report card on the Chesapeake Bay for 2015, scoring it at 53 percent, third highest since since 1986 behind two major drought years.
A sense of urgency indeed.
Without doing something substantial to the dam’s reservoir, these improvements could literally be washed away.