The stormwater management program is a state mandated program delegated to Harford County on September 6, 1984. Historically, runoff from development was only managed during the construction phase of a project through sediment control practices. Stormwater management structures, or best management practices (BMPs) were developed to manage stormwater runoff after the construction phase of the project has been completed. Examples of BMPs are infiltration, flow attenuation, retention, extended detention, and detention.

All new development in Harford County must address stormwater management by obtaining either an exemption or a waiver from stormwater management requirements, or by providing management though the design and construction of a BMP. Water Resources Engineering is responsible for the review and approval of stormwater management waivers, exemptions, and design plans for BMPs.

Development that requires stormwater management must control the proposed peak discharge leaving the site to a level equal or less than the existing peak discharge. The peak discharges that must be controlled are the two (2) and ten (10) year storm discharges. Areas within two watersheds in the County must also provide 100 year management. These two areas are the Bynum Run watershed above Business Route 1 and the Wildcat Branch watershed above Reckord Road.

As part of the stormwater management program, an environmental inspector with the Bureau of Construction Management is required to inspect each BMP during construction and determine whether the facility is constructed to specifications. The Bureau of Construction Management is also required to conduct maintenance inspections for each BMP on a tri-ennial basis. Currently, there are approximately 300 BMPs within Harford County.