Stormwater Management Plan: 12 Things (2024) You Need To Know

In the 1990s, the EPA amended the United States Clean Water Act to address a growing problem – the lack of proper stormwater management planning.

“Why does stormwater matter?” you may be thinking.

Well, did you know that in the 1970s two-thirds of this country’s waters were unsafe for fishing and swimming?

Stormwater runoff was one of the main sources of this pollution.

This is why the Clean Water Act requires many municipalities to create a stormwater management plan.

It ensures that debris, pollutants and chemicals from storm sewers and construction sites do not find their way to the nation’s waters.

And, if you plan to construct a building, you may need to comply with these plans.

Keep reading to learn more!

1. What is a stormwater management plan?

A stormwater management plan is a plan that helps to reduce pollution and contamination by controlling runoff of rainwater or melted snow.

There are two different kinds of stormwater plans:

bulletStormwater Pollution Prevention Plans (SWPPP): this is a temporary plan designed to mitigate any stormwater issues created by a construction project.

bulletStormwater Management Plan (SWMP): this kind of plan is created by a variety of entities, most notably municipalities that have a municipal separate storm sewer system (rather than a combined sewer and stormwater system).

This blog will primarily focus on Stormwater Management Plans.

2. Why is it critical to manage stormwater?

Developing the land disrupts nature.

This disruption affects stormwater rates when it limits and impedes the natural flow of the water and the ground’s ability to soak it up.

Additionally, as this occurs, water runoff becomes contaminated.

As the water rolls over any impermeable surfaces (i.e., rooftops, sidewalks, etc.), harsh chemicals in these locations end up polluting the water.

If and when these chemicals reach local natural water bodies, they can harm and potentially kill any plant or wildlife nearby.

Furthermore, humans end up at risk because these water bodies can be sources of drinking water.

Now, you may think, “How common is this really?”

Even the smallest storm can create water runoff problems, which is why managing stormwater runoff is essential through a stormwater management plan.

3. What are the main problems that stormwater runoff can create?

 The top problems created by stormwater runoff include:


Pollution occurs when water flows over an impervious surface and collects the chemicals on top of it.

Because developed areas host countless harmful substances, they can cause severe damage if they enter a natural body of water.

When this occurs, ecosystems suffer, and drinking water is contaminated.


Water flows off impervious surfaces and forms new paths.

Whenever water moves over land it never has before, it can cause deterioration.

This may also be detrimental to both ecosystems and local communities.


Stormwater runoff can overflow drainage ditches, sewage systems, and storm drains unless proper management is in place.

This flooding can be inconvenient if not dangerous.


Even if water finds land that can absorb it, it may increase sedimentation.

This is called turbidity, or muddiness, which ruins nearby land.

bulletInfrastructure damage

All of the above (flooding, erosion, pollution, and turbidity) can wreak havoc on the local infrastructure.

4. What are the goals of a stormwater management plan?

 The goals of a stormwater management plan include:

bulletReducing flood damage (including damage to life and property)

bulletMinimizing any increase in stormwater runoff from new development

bulletReducing soil erosion from development or construction projects

bulletAssuring the adequacy of existing and proposed culverts, bridges, and other in-stream structures

bulletMaintaining groundwater recharge

bulletPreventing an increase in nonpoint pollution

bulletMaintaining the integrity of stream channels for their biological functions as well as for drainage

bulletMinimizing pollutants in stormwater runoff from new and existing developments to restore, enhance, and maintain the chemical, physical and biological integrity of the waters of the state

bulletMinimizing pollutants in stormwater runoff from new and existing developments to protect public safety through the proper design and operation of stormwater basins

5. How does stormwater runoff affect us?

Stormwater runoff is one of the largest remaining major sources of pollutants in our nation’s waters.

In fact, it’s estimated that over 40 percent of existing water pollution problems are attributable to nonpoint source pollution.

6. Who must create a stormwater management plan?

Municipalities must apply for a permit under the EPA’s National Pollutant Discharge Elimination System (NPDES) if they have a separate storm sewer system (MS4).

This is a stormwater collection system that is separate from the municipal sewer system.

In order to obtain an NPDES permit, the municipality must draft a stormwater management plan.

7. What is included in a municipality’s stormwater management program and plan?

The stormwater management plan should outline a program with the following elements:

bulletPublic education and outreach

bulletPublic participation and involvement

bulletIllicit discharge detection and elimination

bulletConstruction site runoff control

bulletPost-construction runoff control

bulletPollution prevention and good housekeeping

When these elements are implemented in concert, they are expected to produce a significant reduction of pollutants discharged into receiving water bodies.

In addition, the stormwater management plan for the program should also be clear about the following:

bulletWhat needs to happen

bulletWho needs to do it

bulletHow much they need to do

bulletWhen they need to get it done

bulletWhere it is to be done

8. How does my municipality’s stormwater management plan affect me?

As part of their stormwater management program, municipalities will often have regulations on new development.

Some developers mistakenly believe that, because there is already a municipal storm sewer in place, all you need to do is tap into it.

However, these systems can only handle so much, and thus having an excess of water runoff in these systems can lead to flooding or damage to the infrastructure.

This means that you may be required to keep as much storm runoff on-site as possible.

Fortunately, there are many on-site stormwater control measures, including:

bulletBioretention Areas/Rain Gardens

bulletConstructed Wetlands

bulletCurb and Gutter Elimination

bulletDrainage Ditches

bulletPermeable Pavements

bulletRain Barrels and Cisterns

bulletRiparian Buffers

bulletSand and Organic Filters

bulletVegetated Filter Strips

bulletVegetated Swales/Dry Swales

Which system you choose to implement will ultimately depend on your project and location.

Your local county or city will have certain requirements, and you’ll need to cater your project to the guidelines provided.

9. What are the pros and cons of managing stormwater on-site?

Managing surface runoff on-site is largely beneficial, but it does require planning and thought.

Here are the pros and cons.


bulletProper drainage of surface run-off

bulletAbility to recharge groundwater and reuse precipitation water and surface run-off as irrigation or household water

bulletTreatment of stormwater in a very early stage

bulletAvoids damage to infrastructure (private properties, streets, etc.)

bulletFlood prevention

bulletCan be integrated into the urban landscape and provide green recreational areas


bulletExpert planning, implementation, operation, and maintenance required

bulletA lot of operation and labor required depending on the technique

bulletRisk of clogged infrastructure caused by high sedimentation rates

10. How does my municipality fund its stormwater management plan?

Obtaining funding for a stormwater management plan is one of the most crucial steps in the stormwater management process.

The EPA notes that finding the lowest cost funding methods can be challenging for municipalities.

As such, permittees often rely on local revenue bonds or State Revolving Funds for capital to fund combined sewer (i.e. stormwater+sewer) overflow controls.

Generally speaking, there are two categories of funding that municipalities can obtain.

The first is capital funding and the other is annual funding.

bulletCapital funding includes bonds, loans, grants, privatization, and any other capital funding options like special reserves and assessments.

bulletAnnual funding includes fees, taxes, and miscellaneous funds like proffers and capacity credits.

11. How can I get involved?

Municipalities often involve the public during the planning process of their stormwater management programs.

So, keep an eye on whether your municipality is hosting public meetings to discuss its stormwater management program.

In addition, the EPA encourages wider community outreach by suggesting your municipality:

bulletIdentify key users and groups

bulletEstablish an advisory committee

bulletCreate a stormwater utility website

bulletPrepare pamphlets and presentations

bulletMeet with key user groups and the media

bulletDistribute information before initial billing

12. What type of reporting and documentation will your municipality be required to undertake?

The type of reporting that your municipality does on its stormwater management plan will depend.

At a high level, many municipalities will generate reports on the following items:

bulletCompliance with the NPDES permit

bulletThe effectiveness of the stormwater management project

bulletThe chemical, physical, and biological impacts to receiving waters resulting from stormwater discharges

bulletStormwater discharges

bulletSources of specific pollutants

bulletLong-term trends in receiving water quality

Final Thoughts

A stormwater management plan is a detailed document that includes all of your municipality’s efforts to mitigate the impact of stormwater.

While time-consuming, these plans can help to drastically reduce the impact of stormwater on the environment and protect local land, wildlife, and residents.

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Erika Gokce Capital

Disclaimer: we are not lawyers, accountants or financial advisors and the information in this article is for informational purposes only. This article is based on our own research and experience and we do our best to keep it accurate and up-to-date, but it may contain errors. Please be sure to consult a legal or financial professional before making any investment decisions.


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