Retention (stormwater) ponds are essential for neighborhoods as a place to route precipitation and other water, so that the neighborhood doesn’t flood. Proper stormwater pond maintenance is essential not only to avoid destruction from flooding, but for the health and comfort of the community. We interviewed aquatic experts with experience in stormwater pond maintenance from Clarke Aquatic Services in St. Charles, IL to get the details on keeping an effective retention pond with ease.

Retention pond design

Clarke explains that there are two key factors in retention pond design that impact its effectiveness:

Lakes and ponds should be constructed as deep as possible, with mechanical controls or bottom-diffused aeration systems installed from the start.

Aeration systems help ensure plenty of movement in the water. Movement is crucial to stormwater pond maintenance because it introduces oxygen and reduces buildup. Stagnant waters cause a lot of problems for pond management. This also increased the amount of dissolved oxygen in the water, allowing aquatic wildlife to flourish, which makes for easier management of vegetation and algae.

Retention pond problems

Because these bodies of water so crucial to a neighborhood, and because they are their own ecosystem, many retention pond problems can arise. All of them are symptoms that you need stormwater pond maintenance.

  • Ponds grow shallow by filling in, thereby becoming ineffective at their purpose of preventing flooding and overflow.
  • The water is stagnant, causing an excess of organic material and nutrients.
  • An excess of organic material ends up in the pond, such as from grass clippings, animal waste run-off, or rain.
  • The excess of organic material and/or other additions to the ecosystem like fertilizer run-off or pesticides causes excess nutrients in the water.
    Harmful Algal Blooms (HABs)

    Harmful Algal Blooms

  • Excess nutrients result in excessive plant and algae growth, potentially including Harmful Algal Blooms (HABs).
  • These same issues can cause midge flies.
  • Stagnant and otherwise issue-ridden retention ponds are a breeding ground for mosquitos.

7 steps for stormwater pond maintenance

If you suspect you have retention pond problems, or need stormwater pond maintenance, here are the steps to take. Being proactive is definitely best when it comes to retention ponds. Clarke reminds us,

An ounce of prevention is worth a pound of cure.

  1. Do not dump anything into ponds, including fire pit contents, animal waste, or old Christmas trees.
  2. Use fertilizer, pesticides, and herbicides sparingly.
  3. Avoid oils, detergents, leaves, or lawn clippings going down storm drains.
  4. Plant native plants around your pond to help absorb some of the excess nutrients that you cannot avoid, such as from run-off. Known as “littoral plantings”, these robust plants have deep root systems to also help reduce erosion, thereby stabilizing the shoreline.
  5. Create a strip around the pond that you keep un-mowed. This avoids grass clippings in the pond.
  6. Watch for algae that resembles blue or green paint spilled onto the water, thick puffy blue or green foam on the water’s surface, or swirling colors beneath the surface of the water. These may be harmful algae blooms (HABs), and can be harmful to people and potentially fatal to animals. They may also have a distinct grassy, fishy, or septic smell. If you suspect you have HABs, call a professional immediately.
  7. If you suspect it is time for evaluation by a contractor and don’t already have up-to-date data on your pond, obtain water quality readings.
  8. A contractor will be able to take your water quality data and develop a plan integrating chemical and/or mechanical (dredging, aeration) controls, prescription applications, methodologies, and a treatment or prevention timeline.

A retention pond rendered ineffective due to being filled in over time and therefore shallow, or from excess nutrients, increases the risk for flooding from drainage clogs. This can cause damage to properties, landscaping, roads, and vehicles. Avoid retention pond problems now to avoid more disastrous expenses later.


Retention Pond, Warrenville image by Daniel X. O’Neil under CC BY 2.0