SNOW HILL – Three of four Pocomoke River Total Maximum Daily Load pollution limit numbers will not be complete for some time, state of Maryland officials say.
Four substances have been listed as concerns in the Pocomoke River, but only one has been assigned a TMDL, which are being developed by the state as a measure of how much of a substance can enter a water body without harming water quality.
A fecal coliform bacteria TMDL has been established and approved by the U.S. Environmental Protection Agency (EPA) for the Pocomoke River. High levels of this bacteria have caused a state restriction on shellfish harvesting in the lower Pocomoke River and Pocomoke Sound.
The three other substances currently listed as harming the Pocomoke River, but which have not been assigned TMDLs, are the nutrients nitrogen and phosphorous; PCBs; and suspended solids and sediments.
Nitrogen and phosphorous are the most familiar water contaminants to many residents of Worcester County.
“The majority of the Pocomoke will be addressed through the EPA’s [Chesapeake] Bay TMDLs and they are expected in 2010,” said Maryland Department of the Environment TMDL Coordinator Melissa Chatham.
The EPA will set TMDLs for the Chesapeake Bay, said Chris McCabe, natural resources administrator for Worcester County, and then proceed to set TMDLs on nutrients and sediments in the bay’s tributaries, which includes the Pocomoke River.
At some point after that, a PCB TMDL will be set. PCBs, polychlorinated biphenyls, are a legacy problem, said Chatham, because they are no longer produced in the United States.
“They were listed just last year so they’re probably not even on the radar screen at this point for TMDL development,” Chatham said.
TMDL setting is a long process, beginning, Chatham said, with analysis of whether a body of water should be on the state of Maryland’s 303d impaired waters list. If data show that the waterway is impaired, the state pursues a TMDL.
“We may go out and monitor for additional data or do whichever model is appropriate,” said Chatham.
Any trustworthy data will be used, whether from an internal study, an academic study, or from private monitoring groups.
The EPA requires the state to consider all readily available data, said MDE Watershed and Non-tidal Modeling Division Chief Tim Rule.
“Universities, watershed groups, we’d like to see it,” said Rule.
Analysis and modeling determines what substances are polluting a body of water, and tries to pin down the sources of that substance, from point sources originating in agriculture, industry, and government, such as fertilizer application or wastewater treatment plants, to non-point sources such residential run-off or other stormwater sources.
Determining TMDL levels for a polluting substance can take a substantial amount of time.
“The entire process, the EPA specifies a period of eight to 13 years from the point it was listed impaired to the submission of the TMDL for approval,” Chatham said.
TMDLs for substances that are a public health problem can be fast-tracked, but that is not the case with the remaining identified contaminants identified in the Pocomoke River.
Once the TMDL processes for the other Pocomoke River TMDLs begin, setting those pollutant limits should not take as long as eight years, however.
Public participation will be invited when the TMDL processes for nutrients, sediments, and PCBs begin.
Implementation will be a broad effort once the TMDL is established.
“Generally, it’s a collective effort between the counties, cities, states and different properties within their jurisdiction,” said Chatham.
A body of water’s recovery from pollutants, once a TMDL is established and implementation measures are put in place, is difficult to predict.
“You’re talking about a natural system and it has a mind of its own,” Chatham said.