Council hears long update on Edgemont Reservoir: state dam standards, PMP studies and large funding ask

City staff and consultants presented a detailed update on the Edgemont Reservoir and dam rehabilitation at the Feb. 18 work session, describing multi‑agency technical reviews, revised state requirements and a significantly larger project scope and cost than earlier studies had estimated.

Engineering, hydrology and fisheries requirements: staff and project consultant Hazen & Sawyer summarized a sequence of technical milestones. The city’s consultant reported seepage had been identified beneath the spillway in earlier studies and that the state’s updated probable maximum precipitation (PMP) tool and guidance require a larger, more complex spillway design than was used in earlier approvals. The presenter noted the dam was constructed in 1902 and that the last major spillway upgrade occurred in 1993.

Staff said the Maryland Department of the Environment (MDE) has completed a new draft PMP tool and that any final MDE position will strongly affect design and cost. Staff said MDE previously approved funding of $15.75 million for the reservoir project (with $1.5 million as grant and $14.25 million as loan), and that the city submitted an updated application for roughly $34.1 million in total project cost with a local share shown for portions of engineering and related work.

Staff described fisheries and conservation‑flow constraints raised by the Maryland Department of Natural Resources (DNR). DNR expects the city to provide conservation flow and to prevent spawning adult trout from being entrained in the reservoir; screening and flow‑by infrastructure will increase technical complexity and cost. Staff said that because the reservoir captures a portion of a small tributary (Warner Hollow), DNR requires design elements intended to protect downstream aquatic habitat and temperature regimes.

Project scope and timing: staff said earlier estimates (a $2–3 million grout/repair project) have grown to a multi‑tens‑of‑millions construction need because of new PMP and fisheries demands; staff said the city has spent roughly $1.2 million on engineering to date. The consultant noted that MDE’s draft PMP tool, if followed to the same percentile as other states’ updated guidance, would lead to a substantially larger labyrinth/overflow structure than the 1993 configuration. Staff expressed concern about constructability and cost and told council they plan to re‑engage with MDE, DNR fisheries and dam safety to explore options and potential alternatives.

Alternatives and downstream risk: council members and staff discussed the possibility of decommissioning the dam as an alternative and the legal/financial consequences of doing nothing. Staff emphasized that Edgemont remains classified as a high‑hazard dam and that, even empty, it presents a legal obligation to address structural risks and inundation mapping. Staff said a full construction phase could take one to two years once design and funding are complete.

Next steps: staff will re‑kickoff dialogue with MDE, DNR fisheries and dam safety with Hazen & Sawyer, provide updated inundation mapping and emergency action plans to council, and re‑examine design alternatives to reduce constructability risk and cost. Funding applications to MDE remain active; staff said further decisions will be guided by final PMP outputs and agency positions.

Ending: Council and staff agreed to resume formal discussions with state agencies and to return with updated cost, design and schedule information after those conversations.