The Pennsylvania Stormwater Management Act (PA Act 167) was passed in 1978 to
enable municipalities to manage stormwater runoff in a manner that is consistent with
sound water and land use practices. Act 167 required counties to prepare stormwater
management plans (subject to DEP approval) for all watersheds located within the
county and required municipalities to adopt ordinances that regulate development and
growth in a manner consistent with the county’s plans. This DEP webpage provides a
variety of resources on the Act 167 planning process.
In 2024, Chester County’s Board of Commissioners adopted Watersheds 2045: An Integrated Water Resources Plan as its Act 167 plan. Watersheds 2045 incorporates
the 2022 County-wide Stormwater Management Model Ordinance. By 2026, nearly all
municipalities within the County have adopted some version of the ordinance, as
required by state law.
Because stormwater runoff can come from anywhere, the Act 167 Plan and municipal
ordinances help ensure that pollution carried by stormwater runoff from all parts of the
municipality – not just urbanized or developed areas – is limited when it reaches our
streams and rivers.