Retention Ponds: Attractions or Liabilities?

Many churches use retention ponds to control storm water runoff on their property. These ponds can enhance a church’s aesthetic value, but they can also create liability and maintenance issues. Here are some of the problems associated with retention ponds, along with some risk management tips.

Risk #1: Drowning

Children are attracted to water, and retention ponds offer ready access. Unlike swimming pools, these basins typically aren’t fenced in.

They can also be deep and have a steep drop off at the water’s edge, since they’re designed for maximum rainwater collection. Muddy bottoms and slippery sides can make it difficult for someone to escape. 


  • Post No Trespassing signs. Landowners generally have a duty to warn people of dangerous conditions on their property that might lead to reasonably foreseeable injuries. Post signs forbidding trespassing, swimming, skating, or boating to deter people from your ponds. Such signs can reduce your liability if someone were to be injured or drown. However, signs don’t work in all situations, since a pond may attract children too young to read them. If small children are likely to frequent your ponds, you typically must exercise increased care to protect them.
  • Add lifesaving equipment. If your property is located in a housing addition or near an apartment complex, children are more likely to pass near the pond. Consider placing a snatch pole or other life saving equipment near the retention pond, so bystanders could help someone without getting into the water.
  • Install culvert grates. If your culverts are large enough for a child to enter, install grates over them. If a child could be propelled into a culvert by the force of storm water runoff, consider using an angled grate that would force a person upward instead of pinning him underwater.
  • Consider a fence. Erecting a fence would be the best way to reduce the drowning threat posed by a retention pond. However, it may not be a realistic option, based on the pond’s location, size, or aesthetic value.

Risk #2: Mosquitoes

Since mosquitoes breed in any still water they can find, your retention ponds can become a nuisance to residential neighbors. The solution lies in preventing mosquitoes from breeding, either by breaking up the surface of the water or eliminating mosquito larvae.


  • Get water moving. Mosquitoes avoid breeding in moving water. Adding a waterfall, fountain, or aerator will enhance the pond's beauty while preventing it from becoming a mosquito breeding ground. Have a professional aquatic service install water features because of the electrical hazards involved.
  • Eradicate larvae. Hire a certified pesticide applicator to add a natural larvicide to your pond. Several products on the market are safe for people, pets, plants, and fish but effectively eradicate mosquito larvae without harmful chemicals.

Risk #3: Algae

In general, algae are essential for a healthy pond. However, these small aquatic plants can pose a problem when you have too much of it. An algae bloom can reduce the oxygen available to support fish and other plant life within the pond. It’s also unattractive to see a pond covered with green scum.

Algae problems usually occur due to ponds being neglected. While retention ponds require minimal maintenance, you can’t usually “dig a hole” and then let the pond take care of itself. Healthy ponds require proper aeration, integrated pesticide management, and adequate pond weed control.


  • Aerate water. Adding a waterfall, fountain, or aerator helps improve oxygen levels in the pond and can prevent algae blooms. Aeration can cause a shift in the carbon dioxide levels within the pond and, in turn, can cause conditions that favor “good” algae over the undesirable blue green algae.
  • Practice algae control. There are several available methods for algae control, including herbicides, bacteria and microbes, chemicals, UV sterilizers, and other additives. Contact an aquatic management specialist for recommendations on what works best in your area.

Retention ponds are an increasingly popular way to deal with storm water drainage. By posting proper warnings and practicing routine maintenance, you can keep them safe and attractive.