Effective July 1, 2021, the countywide Stormwater Pro Rata Share Assessment rate will change from $23,254.22 to $23,825.20 per increase in impervious acre; the maximum water quality credit will increase from 38.2% to 38.4%; and the maximum water quantity credit will decrease from 61.8% to 61.6%.
As a reminder, the payments collected via this assessment make a valuable contribution to the environment. These funds, aggregated countywide and collected during the development process, pay for needed drainage facilities that minimize damage to receiving waters within Fairfax County as well as the Potomac River and the Chesapeake Bay. They also alleviate flood damage and arrest deterioration of existing drainageways.
The county determines the Pro Rata Share assessment for an individual development project as a proportion of the total estimated cost of the drainage improvement program. The assessment is based on the stormwater impact of the project measured by its increase in impervious cover discounted by any applicable credit for on-site stormwater management facilities and best management practices provided as part of the new construction.
Once collected, the assessment fees will be allocated to the Fairfax County Department of Public Works and Environmental Services for the program. Visit the Stormwater Management page to learn more about typical community improvement projects supported by funding from the Pro Rata Assessment fee and other funding sources.
For more information on Pro Rata Share Assessment, refer to Public Facilities Manual (PFM) § 6-0600.
If you have any questions, please contact the Customer and Technical Support Center at 703‑222-0801, TTY 711.
Public Information Officer
Fairfax County Land Development Services
703-324-2743, TTY 711