What is Integrated Stormwater Management (ISWM)?

As development increases in urban areas, natural landscapes are altered. Grasslands and forests are removed along with their natural abilities to stabilize the existing landscape. Natural features are replaced with impervious surfaces such as concrete and asphalt. The ability for stormwater to naturally soak into the ground is then reduced and the increased quantity of stormwater runoff can contribute to flooding and can transport urban pollutants such as fertilizers, pesticides, oils, animal wastes and trash to our streams and rivers. These bodies of water serve as sources of our drinking water, so it is very important to be proactive and protect them from the impacts of urbanization.

In 2002, the North Central Texas Council of Governments, a voluntary association of more than 60 local governments in the North Central Texas region, developed ISWM Program. The ISWM program is a cooperative initiative that assists cities and counties in the North Central Texas region in achieving their goals of protecting local water resources.

The ISWM Program is designed to 1) encourage environmentally sustainable development and design for the long term and 2) address the impacts of urbanization during the temporary construction phase.

Primary Focuses

The ISWM Program for Development consists of three primary focus areas using the principles of Green Infrastructure and Low Impact Development to protect, restore, or mimic the natural water cycle. The first area of focus deals with protecting water quality.

The goal of this measure is to simply remove pollutants in stormwater. This can be achieved through either:

  • The preservation of natural features that can effectively filter out pollutants
  • The construction of features onsite which can treat pollutants
  • The implementation of measures downstream that can mitigate pollution

The second area of focus is designed to protect streambanks from the increase in water velocity that causes erosion. This can be achieved through either:

  • Downstream reinforcement or stabilization
  • Installation of onsite stormwater controls
  • The controlled release of excessive amount of stormwater

The third area of focus addresses flood mitigation and the transport of floodwaters to minimalize local flooding. This can be achieved through either:

  • Providing adequate downstream systems to safely convey floodwaters
  • Installing onsite stormwater controls
  • Simply maintaining existing conditions onsite

Best Management Practices

The ISWM Program for Construction addresses stormwater runoff while construction is in process. Temporary controls that are used to do this are called Best Management Practices (BMPs). These measures are designed to:

  • Proactively prevent soil erosion on-site
  • Capture sediment on-site when erosion prevention is not feasible
  • Prevent construction materials and wastes from contaminating stormwater

The City of Denton has been recognized as a regional leader in the efforts to protect our water resources. Currently, the City of Denton is recognized as a Silver Level Participant in the ISWM Program and is committed to improving quality of life and protecting the environment while creating economic opportunities for its citizens, businesses and institutions. The City of Denton also has adopted ISWM as part of the Stormwater Design Criteria Manual (PDF).

Benefits of ISWM

  • Keeps safe from the effects of flooding
  • Protects property values by reducing the effects of streambank erosion,
  • Improves water quality
  • Helps local governments address issues of water resources protection and compliance with state and federal regulations

Currently, more than 60 local governments are participating in the ISWM program in order to proactively mitigate the effects of urban development in the region. Find more on the ISWM website.

Show All Answers

1. What is a watershed?
2. Why is watershed protection important?
3. How do I report a spill or discharge impacting a waterway?
4. Where should I drain the water from my pool?
5. Where can I discharge pool filter backwash water?
6. Where can I find out more about Environmentally Sensitive Areas?
7. What is a Stormwater Management Plan?
8. What Is a Phase 2 Small Municipal Separate Storm Sewer Systems (MS4)?
9. What Are the Phase 2 Small MS4 Program requirements?
10. What is an illicit discharge?
11. What is required of an illicit discharge detection and elimination program?
12. What is Municipal Good Housekeeping?
13. What is required of Municipal Good Housekeeping?
14. What is Integrated Stormwater Management (ISWM)?