Flood Zones in Lycoming County: The Greater Williamsport Levee's Recertification

A large, historically proven levee -- but recertification is not automatic

The Greater Williamsport Levee, built by the U.S. Army Corps of Engineers in the 1950s, is the second-largest flood-control system of its kind in Pennsylvania, built to roughly 36 feet along the West Branch Susquehanna River. It proved itself in a real, historic test: during Hurricane Agnes in June 1972 -- one of the most destructive floods in Pennsylvania history -- the West Branch rose to within about a foot of the levee's top, and Williamsport avoided the catastrophic damage that hit many other Susquehanna River communities that year. The Army Corps estimates the levee currently protects on the order of $4 to $5 billion in economic assets and thousands of jobs across north-central Pennsylvania.

That historical performance doesn't automatically satisfy today's federal standards, though. After levee failures during Hurricane Katrina in 2005, FEMA and the Army Corps tightened the engineering and inspection standards a levee has to meet to be formally "accredited" for flood-insurance purposes, and older levees nationwide -- including this one -- have had to go through a fresh, often multi-year recertification process to keep that accredited status. Williamsport's levee recertification effort has been underway for years and is not yet complete as of this research pass.

What's actually happening: relief wells, pump stations, and federal funding

The recertification project has moved through distinct phases: engineering firm WSP was retained to design more than 100 relief wells on the dry (landward) side of the levee, a multi-year design and study effort; the project has drawn a series of federal earmarks (an $8 million FY2023 earmark, with a further FY2024 earmark), administered in partnership with the regional planning agency SEDA-COG; and in 2026, Williamsport City Council approved a construction contract for electrical upgrades at the levee's pump stations -- a concrete transition from planning and engineering into actual construction. The full relief-well design phase alone was projected, as of a 2024 report, to take up to three years, and the overall recertification effort is expected to continue for several more years beyond that.

The stakes for property owners are direct and specific: officials protecting this project have stated plainly that if the levee is not fully recertified and accredited, property owners it protects would be required to carry federal flood insurance -- a real, quantifiable cost that a levee's protected status is specifically designed to avoid. FEMA's flood-insurance framework includes provisional designations, such as its Zone A99 "adequate progress" category, meant to apply specifically to areas behind a flood-control system that's under active construction or remediation toward accreditation -- worth asking about directly rather than assuming a parcel is either fully in or fully out of a mapped flood zone.

What a buyer in Williamsport, South Williamsport, Old Lycoming, or Loyalsock should check

Three concrete steps: (1) check the parcel's current FEMA flood-zone designation directly through FEMA's Flood Map Service Center (msc.fema.gov) rather than relying on an older map or a general assumption that "it's behind the levee, so it's fine" -- the recertification project's status can affect which zone currently applies; (2) ask the City of Williamsport's engineering office or Lycoming County's Hazard Mitigation planning contact for the levee recertification project's current phase and expected completion, since that timeline affects how long any provisional flood-insurance requirement might last; and (3) if buying in South Williamsport, Old Lycoming Township, or Loyalsock Township rather than the city itself, confirm how that specific municipality's flood-insurance requirements are currently being administered, since the levee protects all four jurisdictions but each administers its own floodplain permitting separately under Pennsylvania's municipal system.