Weir introduced in Sligo Creek as part of restoration project

National recognition for Sligo Creek’s successful restoration of aquatic life

May 18, 2012

Montgomery County’s Sligo Creek is getting national recognition for improvements in aquatic life resulting from extensive stormwater pollution control and management in the watershed. EPA has published a case study on Sligo Creek as a Section 319 Success Story. Success Stories are used by EPA to request and justify continued funding from Congress for grant monies (known as Section 319 grants) ear marked for controlling nonpoint source pollution which carries pollutants from urban surfaces and agricultural lands into waterbodies in rainfall runoff.

The County’s biological monitoring program has been sampling fish and other aquatic organisms in the stream for decades. Since 2000 when the fish complex found in the stream were of only four pollution-tolerant fish, steady incremental changes in the creek’s water quality and habitat opportunities have led to noticeable improvement. Today fourteen naturally sustaining fish species can be found in the creek, including some that require specialized habitat. The bioassessment done of the aquatic life in the creek shows that the overall Index of Biotic integrity scoring has improved from a “poor” rating to a “fair”rating.

Stormwater pond in the Sligo Creek Watershed (one of multiple restoration projects)


Restoration Efforts led by the County

Since 1989, the County has

  • improved the stream banks down the length of the Sligo Creek,
  • created wet ponds to capture stormwater runoff and treat it before it goes into the creek,
  • restored pools for breeding habitat for fish and amphibians, and
  • retrofitted existing stormwater ponds by adding additional storage and retention capacity to capture rainfall runoff from additional urban surfaces, and added more meanders and curves which slow down the flow of water during storm events and create habitat niches for biological life.
    Wetland created in the Sligo Creek watershed as part of a restoration effort

    Wetland created in the Sligo Creek watershed as part of a restoration effort


Emphasis on Restoration through Low Impact Development and Environmental Site Design

More recent investments by the County have included installations of low impact development bio-retention systems. These installations help to filter out the pollutants in stormwater runoff and help to absorb the rainfall in place through vegetation roots instead of allowing runoff to flow into gutters and into the stream conveying pollutants.

The Arcola Avenue Green Street Project which integrates curbside swales, rain gardens and curb extensions along the roadway, is an example of a low impact design installation which helps to reduce runoff volumes and pollution that would otherwise flow into Sligo Creek.

Planted roadside vegetated feature which absorbs rainfall runoff along Arcola Avenue in the Sligo Creek watershed

Construction of a roadside vegetated installation which absorbs rainfall runoff along Arcola Avenue in the Sligo Creek watershed

By Ansu John

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