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Maryland Department of the Environment

Department of the Environment Issues Draft Water Quality Report


Jay Apperson

(410) 537-3003

Department of the Environment Issues Draft Water Quality Report

Report notes statewide water quality challenges and opportunities, need for action on Conowingo Dam; draft open for comment, public meeting set

BALTIMORE, MD (February 26, 2018) – The Maryland Department of the Environment has released a draft report that assesses water quality across the state. The draft report is now available for public review and comment.

Maryland’s Draft 2018 Integrated Report of Surface Water Quality is prepared by the department in compliance with the federal Clean Water Act. The biennial report  describes ongoing efforts to monitor, assess, track and restore the chemical, physical and biological integrity of Maryland waters. It also categorizes rivers and streams based on their water quality and any resulting requirement for the development of a plan to meet established pollution limits (Total Maximum Daily Load, or TMDL) or other appropriate remedies.  

MDE’s work to evaluate Conowingo Dam owner Exelon Generation Company LLC’s application for a 50-year license renewal for compliance with Maryland Water Quality Standards and requirements spurred a renewed effort to collect and assess biological, habitat, and water quality information in the area. The data revealed conditions that MDE was required to consider in developing the 2018 Integrated Report.

“These findings underscore the need for action at the Conowingo Dam to improve water quality in the Susquehanna River and the Chesapeake Bay, Maryland’s greatest natural asset,” said Maryland Environment Secretary Ben Grumbles. “Maryland will use all available tools to protect and restore the Susquehanna River and Chesapeake Bay in the relicensing of the Conowingo Dam. We look forward to continuing to work with Exelon and many other partners on this environmental priority.”

The data supported a new listing of impairment for total phosphorus for the public water supply designated use for the Conowingo Reservoir, the water immediately upstream of the dam. The Conowingo Reservoir is a backup source of drinking water for Baltimore City’s public water system. MDE assesses water supply reservoirs for indicators of increased phosphorus levels based on the potential for algae growth and any additional water treatment to meet Safe Drinking Water Act standards to protect public health. Even with total phosphorus levels increased in untreated water, treated drinking water must meet all standards to protect public health.

The data also supported a listing of impairment for flow alteration – changes in depth and flow velocity – for the aquatic life and wildlife designated use for the portion of the Susquehanna River immediately downstream of the dam. Exelon largely controls the flow through Conowingo Dam.

The findings are in addition to the implications to Chesapeake Bay restoration presented by discharges of sediment and nutrients from the operation of the Dam.  They also add potential issues in the proposed relicensing of the dam and the related requirement that Exelon show that discharges from the facility will comply with Maryland water quality standards and requirements established under the federal Clean Water Act.

Additional challenges, water quality successes

Other persistent challenges facing Maryland include increasing effects on water quality that appear to be linked to the widespread use of road salt deicers. MDE has now documented 28 watersheds as impaired for chloride, a road salt component that can be toxic to aquatic life. The report describes efforts underway to manage these challenges.

The report also describes water quality successes in the past several years. In 2016, submerged aquatic vegetation coverage, a key indicator of water clarity, reached the highest level recorded in the Chesapeake Bay and tidal tributaries since aerial surveys began in 1984. For the third straight cycle of preparing the Integrated Report, specific restoration projects undertaken by the state have been directly linked to attainment of water quality criteria. For example, MDE’s Abandoned Mine Lands Division used Clean Water Act funding to coordinate construction of acid mine drainage treatment systems in the Casselman River watershed in Garrett County.

Public participation process

The public review period for the draft 2018 Integrated Report began February 16 and runs through March 19. MDE is hosting a public informational meeting and conference call February 27 at the agency’s Baltimore headquarters. Information on the meeting and on directing questions or comments is on MDE’s website. After addressing all comments received during the public review period, a final Integrated Report will be prepared and submitted to the U.S. Environmental Protection Agency for approval.

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