Stormwater Detention Basins

The purpose of this information is to explain the function and maintenance requirements to owners regarding their detention basins. The City of Lincoln requires these detention basins to be maintained per Lincoln Municipal Code (26.23.170) and will routinely conduct compliance inspections to ensure these areas are functioning properly.

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Function

The detention basin (or retention pond) in your neighborhood serves as a critical flood control component of our city's stormwater management infrastructure. Detention basins help manage the excess urban stormwater runoff generated by impervious surfaces such as roads, parking lots and rooftops. They also help prevent localized flooding by temporarily storing the excess runoff in a controlled area and then slowly releasing it at a designed rate.

Obligated Maintenance

When detention basins are neglected, they can become unsightly, which can affect property values. Even worse, they can become a liability. Blocked inlet/outlet structures, for example, can cause flooding in heavy rainfall events. Failure to correct issues noted from a city inspection can result in enforcement and possible further legal action by the City.

Preventative actions to detention basin areas can help preserve natural floodplain functions and alleviate future costs to property owners. Suggestions for prevention are below:

• Ensure all abutting property owners are aware this area is not a dumping ground for grass clippings, leaves, trash, etc.
• Control excess vegetation by mowing and removing dead vegetation on an annual basis.
• Remove small volunteer scrub trees growing within 10' of any structures and on top of or on the slopes of dam embankments.
• Remove debris/trash from the basin and surrounding areas and dispose of properly.
• Install native plantings adapted to floodplain and wetland conditions to help reduce mowing costs and encourage a healthy habitat for wildlife.
• Erosion issues can become worse over time and may lead to higher repair costs if not addressed in a timely matter.

For additional help or question, please contact NPDES@lincoln.ne.gov.

Residents living near a detention basin may want to consider purchasing flood insurance, even if they don’t live in a floodplain. Homeowners insurance policies typically do NOT cover flood damage. Contact your insurance agent for more information.

Common Issues With Detention Basins

Standing Water/Scour Holes Erosion Issues Volunteer Trees Sedimentation Structural Damage Lack of Vegetation

Problem	Effects	Possible Solutions
Excessive vegetation & invasive plants	Blockage of inlet or outlet structures Decreased water infiltration Decreased storage capacity Increased risk of flooding Streambank erosion	Mow prairie areas once per year Mow turf grass and other areas frequently Plant vegetation appropriate for each type of storage facility Remove/manage weedy vegetation, volunteer trees and invasive species
Shoreline or streambank erosion	Buildup of sediment in the pond or other storage facility Decreased storage capacity Increased risk of flooding Inlet/outlet structure damage or failure	Install boulders or rip-rap on pond shoreline Plant vegetation appropriate for shoreline stabilization Remove debris and trash frequently, especially after a rain event Seek professional guidance for streambank erosion
Mosquito population	Increased annoyance to residents Increased risk of spreading mosquito-borne diseases	Maintain a healthy balance of plants, fish and other mosquito predators in ponds Eliminate low spots or scour holes Consult the Health Department for advice
Litter accumulation	Blockage of inlet or outlet structures Streambank erosion	Remove debris and trash frequently, especially after a rain event Cut back overgrown vegetation
Geese population	Excessive goose waste May upset the nutrient balance within pond Increased algae growth	Do not feed geese Plant native vegetation along the banks and minimize mowing Plant “rough” grasses such as buffalo grass
Mowing & yard waste disposal	Buildup of decaying organic material in storage facility	Dispose of yard waste at the city composting facility or use a mulching mower Reduce the use of pesticides and phosphorus fertilizers
Pollutant infiltration	May upset chemical and biological balance of the pond or other storage facility	Dispose of pet waste properly Reduce the use of pesticides and fertilizers
Development of gullies, scour holes or low areas	May cause standing water or soggy surfaces Increased mosquito populations Streambank erosion Decreased quality of turf	Fill areas of standing water with soil Replant eroded areas with grass and stabilize with an erosion control device until the grass has fully matured Consider installing permanent solutions such as erosion control mats
Sedimentation	Decreased storage capacity Increased risk of flooding Buildup of decaying organic material in storage facility May cause erosion further downstream	Remove sediments that accumulate in forebays, drainage structures or stormwater facilities Remove debris and trash frequently, especially after a rain event Consult a professional to install sediment trapping devices for easier/less costly maintenance