Stormwater Management Structures

The Stormwater Management Division's responsibilities include the inspection of over 2,500 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 4,500 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 or duckweed? - The aesthetic issue is typically caused by the amount of fertilizers that are running off of properties and getting into the pond. Please see the Howard County Stormwater Management Pond Maintenance Aquatic Vegetation Management Policy.

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. Please visit

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.