Urban Recharge Myth: Case Study of Montgomery County, Maryland

To prevent adverse impacts of stormwater runoff, the State of Maryland has developed fourteen performance standards that must be met at development sites. Standard No. 3 states that “annual groundwater recharge rates shall be maintained by promoting infiltration through the use of structural and non-structural methods. At a minimum, the annual recharge from post development site conditions shall mimic the annual recharge from pre-development site conditions”.  This standard implies that urbanization has decreased groundwater recharge and that groundwater levels in urban areas are lower than pre-development levels.  This talk will explain the fallacy in this implication by describing groundwater conditions in Maryland’s most populous county, Montgomery, a dense urban county located just outside Washington D.C.  In addition, the effects on increasing groundwater recharge on groundwater levels and groundwater quality will be described.