The Pennsylvania Department of Environmental Protection has officially designated the Lake Wynonah Dam in Schuylkill County as “Unsafe” and is calling for the immediate complete drawdown of the reservoir as state officials cite longstanding seepage, a deteriorating spillway and concerns over the dam’s ability to safely handle a major flood.
DEP issued the designation in an August 14 letter to Brian Magazu, president of the Lake Wynonah Property Owners Association. The dam, located in South Manheim Township, had already been classified as a high-hazard dam.
Lake Wynonah is the larger of two lakes within the private gated Lake Wynonah community near Auburn, which includes approximately 1,425 homes. The lake covers approximately 175 acres.
The latest action follows concerns that surfaced last year when new and increased areas of seepage were observed along the dam. In October, DEP recommended a controlled partial lowering of Lake Wynonah to approximately 20 feet below its normal pool elevation.
Now, DEP wants the reservoir completely drained.
In its August 14 letter, DEP requested a “voluntary and immediate complete drawdown” at a rate of no more than one foot of reservoir depth per day. The agency warned that if the drawdown is not immediately commenced, it plans to pursue heightened enforcement.
The complete drawdown would lower the lake approximately 90 feet, according to information provided to Skook News.
DEP Cites Decades of Seepage Concerns
According to DEP, concerns involving the integrity of the dam's embankment are not new.
A 2014 seepage evaluation documented seepage occurring shortly after the dam's construction and increasing over several decades. That report concluded there was evidence of ongoing internal erosion within the dam's embankment and foundation and raised concerns about potential failure modes associated with seepage.
DEP also pointed to the condition of the dam's concrete spillway, describing it as poor from both a structural and long-term deterioration standpoint.
Recent inspections have documented concrete spalling, delamination of the spillway floor, damaged concrete joints, seepage at joints and instability of the spillway sidewalls. Portions of the walls have also been braced to reduce the chance of a collapse.
The Lake Wynonah Dam was constructed in 1971.
Another major concern identified by DEP involves the dam's ability to handle an extreme flooding event.
A 2025 hydrologic and hydraulic analysis found that a Probable Maximum Flood would produce an inflow of approximately 17,400 cubic feet per second. Under that scenario, water would rise approximately 2.5 feet above the existing top of the dam.
DEP said the existing dam and spillway can pass only approximately 60% of the Probable Maximum Flood without overtopping, which the agency said would likely result in dam failure.
A comprehensive risk analysis conducted by DEP subsequently determined that Lake Wynonah Dam has a “high risk of failure.”
DEP Says Designation Does Not Mean Failure Is Imminent
Despite the “Unsafe” designation, DEP stressed that it does not mean officials believe the dam is in immediate danger of collapsing.
“The ‘Unsafe’ designation is not to suggest that this Dam is at risk for imminent failure,” DEP stated in the letter.
Instead, the agency said the dam is severely deficient in meeting requirements under Pennsylvania's Dam Safety and Encroachments Act and DEP regulations.
State regulations define an unsafe dam as one with deficiencies that, if left uncorrected, could result in failure and the subsequent loss of lives or substantial property damage.
Under those regulations, actions required to address an unsafe dam can include draining the reservoir and submitting either a plan to remove the dam or a permit application to repair and rehabilitate it. Once approved, the owner must undertake the necessary removal or repair work.
DEP has provided the Lake Wynonah Property Owners Association with a Consent Order and Agreement outlining timelines for bringing the dam into compliance. DEP requested comments or questions regarding the agreement within two weeks. If an agreement cannot be reached within four weeks, DEP said it may issue an Administrative Order instead.
Engineers Studying Dam as Residents Face Uncertain Costs
The Lake Wynonah Property Owners Association has contracted with Schnabel Engineering to conduct a structural analysis of the dam and develop recommendations for remediation. Those recommendations are expected to be submitted to DEP for review and approval.
The potential cost of rehabilitating the dam is expected to run into the millions of dollars, raising concerns among residents about possible future assessments from the property owners association and the effect an extended lake drawdown could have on property values.
Not everyone agrees that completely draining Lake Wynonah is necessary.
Lake Wynonah resident and dam engineer Timothy M. Brouse, P.E., of Alta Design Associates, Inc., strongly disagrees with DEP's requested complete drawdown and is proposing alternative engineering approaches that he believes could allow the dam to be remediated without completely draining the lake.
DEP's letter also identifies several additional regulatory matters that must be addressed. The dam's Emergency Action Plan, last acknowledged by DEP and the Pennsylvania Emergency Management Agency in 2021, is due for its required five-year update. DEP also said the property owners association has not provided required Proof of Financial Responsibility for the dam.
For financial responsibility purposes, DEP estimates that permanently breaching the dam, if necessary, would require removing approximately 231,500 cubic yards of material and creating a breach approximately 35 feet wide at the bottom and 403 feet wide at the top. The association's professional engineer can challenge those estimates by submitting an analysis to DEP.
The immediate focus, however, is on lowering the reservoir while engineers and the property owners association determine how to address the deficiencies identified by the state.
DEP has made clear that the complete drawdown should begin immediately and that further enforcement could follow if it does not.
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