Stormwater Management Structures

The Stormwater Management Division's responsibilities include the inspection of stormwater structures in the County. Generally speaking, the maintenance of stormwater management structures is dictated by the maintenance agreement that the County has with the property owner. However, privately owned structures located in commercial areas are maintained by the property owner.


What are stormwater management structures?

Stormwater management structures are structures designed to collect and control runoff from precipitation that falls on the land. Many of these structures are ponds, but other types of stormwater management structures may include underground storage structures, usually located under parking lots in commercial areas, and curbside inlets that remove oil and grit from storm water runoff. Currently, there are over 7,700 active stormwater management structures located throughout Howard County.


Types of stormwater management structures

Click below to see the operation and maintenance for specific stormwater management structures.

Baysaver    Bioretention    Dry Pond (First Flush)       Dry Pond   
Dry Well – Non Residential     Dry Well – Residential     Enhanced Filter Extended Detention Structure Dry (Pond)    
Extended Detention Structure Wet (Pond)    Filter       Filterra       Forebay      
Gravel Wetland       Green Roof       Infiltration Basin       Infiltration Berm    
Infiltration Trench Landscape Infiltration Oil/Grit Separator Open Channel Swale
Permeable Paving Rain Garden       Rainwater Harvesting    Reinforced Turf   
Sand Filter    Shallow Marsh    Stormceptor    Underground Sand Filter   
Underground Storage (Gravel) Underground Storage Wet Pond (First Flush) Wet Pond

Why do we need to manage stormwater?

We need to manage stormwater because development removes wooded and grassed areas and replaces them with roads, homes and businesses. Stormwater is not able to percolate into these impervious structures and cannot flow naturally into the nearby rivers and streams. Instead, development increases the flow and force of stormwater thus resulting in increased and unnatural flows into our stream banks. This can lead to erosion, damaged wildlife habitats, and flooding.

With proper stormwater management, rain water is directed into a local stormwater management structure where it is stored and slowly released into our nearby streams. As stormwater is stored in these structures, sediment and other pollutants have an opportunity to settle out, thus improving water quality.


Contractors providing stormwater management facility maintenance

Aboveground Contractors
Underground Contractors


Frequently Asked Questions


How often does the County inspect my stormwater management facility?

The County inspects stormwater management facilities every 3 years.

How much will it cost to maintain my stormwater management facility?

The cost can vary depending on the type of stormwater management facility. Routine maintenance such as mowing, trash/debris removal and landscaping may be less expensive than non-routine maintenance. Non-routine maintenance may include sediment removal or structural repairs such as pipe replacement. It is recommended to get several estimates from qualified contractors.

Who maintains a publicly owned pond?

The Howard County Bureau of Highways - 410-313-7450

What if my pond is covered with algae?

There are many stormwater management ponds in the county which permanently retain water by design to improve the region’s water quality. Some of these ponds may have algae or other aquatic vegetation. This vegetation may result from excessive nutrients, but algae and vegetation are not harmful, they are evidence that the pond is functioning as intended.

Please see the Howard County Guideline for Common Aquatic Plants, which will help identify aquatic plants you may observe in your community pond or lake. If you are concerned about aesthetic issues related to vegetation, the guideline identifies possible plant control methods, and explains the role plants play in pond ecology and the maintenance of water quality.

*Howard County does not treat publicly owned or maintained stormwater management ponds for algae and/or other aquatic vegetation.

If the stormwater management pond is privately owned and maintained, the owner may control the algae or aquatic vegetation with approved herbicides. Any application of herbicides or pesticides to any body of water must be in accord with State and local law. The contractor applying the herbicides must be licensed by The Maryland Department of Agriculture (410-841-5700), hold a Toxic Materials Permit from The Maryland Department of the Environment (410-537-3003), and comply with the provisions of MDE’s NPDES General Permit MDG87.

Improper application of herbicides or pesticides to any body of water may potentially result in an illicit discharge. For further information or to report an illicit discharge, please contact the Howard County Stormwater Management Division, Cynthia Alden 410-313-6447 or Calden@howardcountymd.gov.

What can I do about mosquitoes?

The Maryland Department of Agriculture should be contacted regarding concerns about mosquitoes. Please see ways to reduce risk. In addition, please see fact sheet regarding West Nile Virus.


Zika Awareness

The Howard County Health Department has posted information on the County website regarding the Zika Virus.


Community Involvement

Stormwater management ponds, can provide unique opportunities for fostering stewardship of the environment. In addition to providing stormwater control, ponds can offer habitats for geese, turtles, and other wildlife.

Communities can enhance the ponds in their communities and make for cleaner local streams and the Chesapeake Bay by:

    • picking up trash around the pond,
    • not dumping grass clippings or leaves on or into pond,
    • limiting the use of lawn fertilizers and herbicides on their lawns that can then run off into the pond,
    • not disturbing vegetated areas around the pond,
    • not discarding chemicals, such as antifreeze and motor oil, down storm drains,
    • not washing their cars in their driveways.

More Information

Questions regarding maintenance of County maintained storm water facilities can be directed to John Slater at the Stormwater Management Division 410-313-6444.