Runoff from paved areas causes erosion and flooding, and contributes to pollution. Streets, roads, and bridges comprise two-thirds of all paved surfaces in the U.S. Thus, our nation’s transportation assets pose unique stormwater challenges for public agencies and the communities they serve.
While working to minimize environmental impacts, agency managers must continually evaluate their approach to regulatory compliance while meeting safety and mobility goals. This balancing act must also take increasing costs and resource limitations into account.
In July 2014 EPA issued a memorandum acknowledging some of these unique challenges. “Transportation MS4 management differs in some ways from traditional MS4s (e.g., cities and towns). Some of the differences include:
“Linear transportation systems often stretch for many miles and cross numerous waterways, watersheds, and jurisdictions. (In other words, a state DOT with facilities in every watershed in the state could be listed in multiple total maximum daily load [TMDL] requirements.)
- “Transportation storm conveyance systems often discharge stormwater and associated pollutants that originate outside of the transportation right-of-way. (Agencies shouldn’t be held responsible for pollution they didn’t produce.)
- Transportation systems often serve a literally transient population. (It’s tough to rally support when you don’t have stakeholders with a vested long-term interest.)
- “There is little to no enforcement authority to implement ordinances. (Anything enacted at the local level in an effort to address the problem could be rendered moot by state and/or federal law.)”