Detention Pond Vs Retention Pond: All The Differences Explained

Ever saw a large pond near a residential or commercial block, or while driving on the highway outside of Houston? 

If yes, there’s a good chance what you saw was either a stormwater detention or retention pond. 

And yes, both these ponds are different. While retention ponds are meant to hold water permanently, detention ponds collect stormwater during rain and then slowly release it.

In this blog, I have explained all the differences between detention pond vs retention pond. So read on to know: 

• What is a detention pond
• What is a retention pond
• The difference between detention and retention ponds
• And much more.

Key takeaways

• A detention pond stores stormwater temporarily and slowly releases it through an outlet.
• A retention pond keeps a permanent pool of water.
• Detention ponds are used to control peak stormwater flows and reduce downstream flooding.
• Retention ponds offer both stormwater control and water-quality benefits.

What is a detention pond?

A detention pond is a basin engineers design to store stormwater runoff during and after rainfall.

You see, buildings, roads, parking lots, and other impervious surfaces, all cause rainwater to run off faster than it would from natural ground. And if all of that runoff reaches the downstream drainage system at once, it increases the risk of flooding and even soil erosion.

This is why a detention pond becomes helpful and is sometimes even required as part of SWPPP prevention plans across Texas.

So, whenever a storm happens, the runoff enters the detention basin and temporarily fills the available storage area. And an outlet structure then controls how quickly the water leaves the pond after the storm. Once the storm passes, the stored water is gradually released.

This is also why a detention pond remains mostly dry when there’s no rainfall happening. 

What is a detention basin?

A detention basin is very much the same thing as a detention pond. It is just that different projects and areas use different terms. 

Also, detention basins can be a big grassy depression, an excavated pond, and even an engineered underground storage system. But the basic components remain the same in all these structures, and include: 

• Inlet: To bring stormwater into the basin.
• Storage area: To temporarily hold the runoff.
• Outlet structure: To control the discharge rate.
• Emergency overflow: To provide a safe path for water during extreme events.

What is a retention pond?

A retention pond is different from a detention pond because it maintains a permanent pool of water.

You have probably seen these ponds in neighborhoods and commercial developments. Unlike a dry detention basin, there is normally water sitting in the pond even when it hasn’t rained recently.

A retention pond is also called a wet pond or wet basin.

The permanent pool gives the pond another function apart from just controlling stormwater. Here, as the runoff enters the pond, sediment and pollutants settle out, while aquatic vegetation and biological processes help improve water quality.

Meaning, the scope of a retention pond is beyond just water storage, and includes: 

• Stormwater storage
• Peak flow control
• Sediment settling
• Pollutant removal
• Aquatic habitat
• Landscaping and aesthetic benefits

Civil Engineer’s Tip: Don’t assume that a pond with permanent water is better than a dry detention pond. The two systems are designed for different purposes, and the right one depends on your property’s exact drainage requirements.

Detention pond vs retention pond: What are the differences?

The main difference between retention and detention pond is that one stores stormwater temporarily while the other maintains a permanent pool of water

Here are all the differences between retention pond vs detention pond: 

Detention pond

1. Temporarily stores stormwater

A detention pond holds excess stormwater during and after rainfall. It then slowly releases the stored water through a controlled outlet.

2. Stays dry between storms

Once the stored stormwater has drained, the pond is dry or mostly dry until the next rainfall.

3. Primarily controls peak-flow 

The main purpose of a detention basin is to reduce the peak rate of stormwater leaving the property. This helps prevent downstream drainage systems from becoming overloaded.

4. Water is released through a controlled outlet

An outlet structure controls how quickly water leaves the pond. This helps regulate the discharge rate rather than allowing all the runoff to leave at once.

5. Simpler to maintain

Since there is usually no permanent pool of water, maintenance involves checking the basin, vegetation, sediment, inlet, outlet, and embankments.

Retention pond

1. Maintains a permanent pool

A retention pond is designed to keep water in the pond even when there is no recent rainfall. The water level rises during storms and then returns toward its normal level.

2. Contains standing water

Unlike a detention pond that can become dry, a retention pond has water throughout the year, although drought and other site conditions can affect the water level.

3. Provides flow control plus water-quality benefits

A retention pond helps manage stormwater while also allowing sediment and some pollutants to settle. It also provides additional water-quality and habitat benefits when properly designed.

4. Permanent pool remains and excess water is managed 

The normal pool stays in the pond, while additional stormwater above the normal level is released. 

5. Requires management of water, vegetation, and sediment

Since the retention pond contains permanent water, it needs extra maintenance for aquatic vegetation, sediment buildup, water quality, and the surrounding area.

In short, here are all the differences between detention pond vs retention pond: 

Can a property have both detention and retention ponds?

Yes, it can.

You see, a stormwater system need not be strictly a detention pond or a retention pond. Some ponds are designed with a permanent pool of water plus additional storage above that pool for storm events.

This means, a retention pond can also provide detention storage when a storm increases the water level above the normal pool.

The Texas Water Development Board describes this type of system as a wet pond with a permanent pool and additional temporary storage above it.

Retention pond vs detention pond: Which is better? 

The better choice between detention basin vs retention basin depends on your property and what exactly you want out of the pond. 

A detention pond makes sense when your main goal is to temporarily store storm runoff and control the peak water discharge from your property.

A retention pond is appropriate when your property can support a permanent pool of water and there are additional things you want to do like water-quality treatment, landscaping, or habitat.

Here’s how I suggest you decide between detention pond vs retention pond: 

Bonus: Here are a few things to consider when deciding between detention and retention pond

• Available space: Does your property have enough room for the required pond?
• Soil conditions: Can your site support a permanent pool?
• Groundwater: Will groundwater conditions affect the pond?
• Drainage patterns: Where is runoff coming from and where does it need to go?
• Downstream conditions: Can the receiving drainage system safely handle the discharge?
• Local requirements: What does the applicable city, county, or drainage authority require?
• Maintenance: Who will maintain the pond after construction?

Conclusion

I am sure that you now have a much better understanding of the difference between detention pond vs retention pond.

As you can see, detention temporarily holds stormwater while retention maintains a permanent pool of water.

Are you planning a development in Houston or anywhere in Texas and aren’t sure whether you need a detention pond, retention pond, or another stormwater management solution?

Well, you can get in touch with us!

At Bullseye Engineering Inspection, our civil engineering services are backed by decades of local expertise and experience.

We help developers, contractors, investors, and property owners make informed engineering decisions throughout every stage of their projects.

FAQs about detention pond vs retention pond

What is the difference between a detention pond and a retention pond?

The main difference is that a detention pond temporarily stores stormwater and releases it at a controlled rate, while a retention pond maintains a permanent pool of water. 

Is a detention pond always dry?

Mostly, yes. 

A dry detention pond is designed to drain after a storm and remain dry between significant rainfall events. 

Does a retention pond always have water?

A traditional retention pond is designed to maintain a permanent pool of water. However, drought, groundwater conditions, and other factors can affect the actual water level.

Which is better, a detention pond or retention pond?

Neither is better. The right choice depends on your property’s drainage conditions, available space, soil and groundwater conditions, water-quality goals, and applicable local requirements.

Is a detention basin the same as a detention pond?

Yes. In many projects, the terms are used to describe the same type of stormwater facility.

Detention basin is more commonly used in engineering and drainage documents, while detention pond is more common in everyday conversation.

Can a retention pond also provide detention?

Yes. A retention pond can have a permanent pool with additional storage above the normal water level to temporarily store runoff during a storm.