If you’ve ever driven through Grand Island, you’ve likely seen large ponds or low areas of water in parks, neighborhoods, or near new developments.
Some of them look like small lakes. Others are dry most of the time. Some have vegetation around the edges, while others are open water basins.
So what are they actually for?
These features are part of our stormwater system—and they play an important role in reducing flooding and improving water quality.
They are generally called:
- Retention ponds
- Detention basins
- Constructed wetlands
Each serves a slightly different purpose, but they all help manage stormwater.
Why We Use Stormwater Ponds
When it rains, water runs off roofs, streets, parking lots, and lawns.
If that water moved directly into storm drains without any control, it could overwhelm pipes and ditches during heavy rain.
Stormwater ponds help by:
- Slowing down runoff
- Storing excess water temporarily
- Reducing flooding in neighborhoods
- Allowing sediments and pollutants to settle out
They act as a “buffer” between developed areas and downstream waterways like local creeks, lakes, and the Platte River system.
Retention vs. Detention: What’s the Difference?
These terms are often used interchangeably, but they are not the same.
Retention Ponds
Retention ponds are designed to hold water permanently.
- They always contain some level of water
- They release water slowly through infiltration or controlled outlets
- They often include plants and aquatic habitat
Because water remains in the pond, sediment and pollutants can settle over time, improving water quality.
Detention Basins
Detention basins are designed to temporarily store water.
- They may be dry much of the time
- They fill during rain events
- They slowly release water after storms pass
Their main purpose is flood control—reducing peak flows during heavy rain.
Constructed Wetlands: Nature Working as Infrastructure
Constructed wetlands are designed to mimic natural wetland systems.
They combine shallow water, vegetation, and slow-moving flow to:
- Filter sediment and nutrients
- Support wildlife habitat
- Improve water quality
- Reduce downstream pollution
Plants play a major role by slowing water and helping trap or absorb pollutants.
These systems are a strong example of green infrastructure working alongside traditional stormwater pipes.
What Happens Inside a Pond During a Storm
When it rains heavily:
- Water flows into the pond from storm drains or channels
- The water level rises temporarily
- Sediment begins to settle to the bottom
- Plants and soil help trap additional pollutants
- Water is slowly released or absorbed after the storm
This process reduces the amount of debris and pollution that reaches downstream waterways all at once.
Why These Systems Matter for Flooding
Without ponds and basins, stormwater would move much faster through the system.
That can lead to:
- Higher water levels in ditches and streams
- Increased risk of street flooding
- Erosion along waterways
- Strain on storm drain infrastructure
Stormwater ponds help spread that flow out over time, reducing peak flooding impacts.
Why They Sometimes Look “Messy” or Overgrown
Stormwater ponds are not maintained like decorative lakes.
You may notice:
- Tall grasses or native vegetation
- Changing water levels
- Sediment buildup at the edges
- Standing water after storms
These are normal and often intentional design features.
Vegetation is important because it:
- Slows water
- Filters pollutants
- Stabilizes soil
- Supports wildlife habitat
A more natural appearance often means the system is functioning as intended.
How This Connects to Water Quality
Stormwater ponds help improve water quality by:
- Allowing sediment to settle before it reaches rivers
- Reducing nutrients that contribute to algae blooms
- Filtering debris and pollutants through vegetation
- Slowing the movement of contaminated runoff
While they do not remove all pollutants, they significantly reduce the amount and intensity of pollution reaching downstream waterways.
What You Can Do
Residents can help protect these systems by:
- Not dumping grass clippings, leaves, or trash into ponds or drains
- Keeping fertilizers and chemicals out of runoff pathways
- Picking up pet waste near parks and drainage areas
- Staying on designated paths to protect vegetation buffers
- Reporting illegal dumping or debris buildup
Small actions upstream help keep these systems working properly.
Why It Matters
Stormwater ponds, basins, and wetlands are not just landscape features.
They are an essential part of how our community:
- Manages heavy rainfall
- Reduces flooding risk
- Protects local lakes and rivers
- Supports groundwater and downstream water quality
They work quietly in the background during every storm, helping protect neighborhoods and waterways across Grand Island.
Our Water, Our Responsibility.