for pollution in stormwater drainage from impervious surface runoff.
A stormwater management fee was established via House Bill 987 (April 2012) and signed into law by then-governor Martin O'Malley, affecting the largest urban jurisdictions in Maryland (nine counties and the City of Baltimore) in order to meet the requirements of the federal Clean Water Act as it concerns the Chesapeake Bay watershed. The Tax Foundation states House Bill 987 "was passed in response to a decree by the Environmental Protection Agency (EPA) formally known as the Chesapeake Bay Total Maximum Daily Load, which identified mandatory reductions in nitrogen, phosphorus, and sediment that damage the Chesapeake Bay." This mandate from the EPA was mandated to the states of Maryland, New York, Pennsylvania, West Virginia, and the District of Columbia. Maryland is the only state that has levied a tax to meet the EPAs standards.[4] Polluted runoff is the only source in the Chesapeake Bay watershed that is still increasing, as of 2018.[5][6] This tax, of course, does not tax rain but has been implemented in varying ways at the county level, such as a flat fee per property owner, or based on impervious surface square footage.
The law specifies that accrued funds must be used for specified stormwater pollution-related purposes.[7]
This law was modified in 2015 to make the county-assessed fees optional rather than mandatory while still holding the counties responsible for making progress on managing polluted runoff.'
https://en.wikipedia.org/wiki/Rain_tax