Welcome to the Minnesota Stormwater Manual website. The Manual is designed to be a user-friendly and flexible document that guides users directly to the information they need, depending upon the question they need to answer or Best Management Practice (BMP) they need to design. This website was developed in an interactive wiki format to make it easy for the user to get to the subject of interest and to move between subjects. You can access the Manual Table of Contents by clicking on the link below.
Stormwater Manual Table of Contents
Contents
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Acknowledgements
This Manual was initiated by the Minnesota Stormwater Design Team, which evolved into the Minnesota Stormwater Steering Committee (SSC). Manual production was directed by the SSC’s Manual Sub-Committee (MSC). A listing of contributors and participants in the process appears in the Acknowledgements section.
Guidance on use of the website
For new users of this website, we have provided Guidance on how to use this website and the Manual.
What's new?
We will attempt to provide frequent updates to users of the Manual. Updates will focus primarily on content of the Manual and will not include minor changes and corrections.
Frequently asked questions (How do I ...?)
Below are some quick links to answer the question: "How do I..."
- Determine if I am covered by the Phase II Construction, MS4 or Industrial permit rules? See Regulatory information, Stormwater Program.
- Pick proper quantity and quality modeling/hydrological factors? See Available stormwater models and selecting a model, Recommended models and calculators for volume, water quality and credit calculations, or Calculating stormwater volume and pollutant reductions and credits
- Pick a BMP? See Using the treatment train approach to BMP selection or Process for selecting Best Management Practices
- Design a BMP? Chapters for each structural BMP in this manual have aan article on design criteria. You may access an article on design criteria by going to the BMP of interest. All articles on design criteria have also been combined as a category. You can access categories in the left toolbar. In the Navigation section, click on Categories and follow find the link to the page called Design criteria.
- Consider the effects of cold weather on the choice and operation of a BMP? > Ch. 9
- Incorporate better site design/low impact development into my stormwater management work? > Ch. 4
- Find out if my site impacts a “special water” ? > App. F
- Find out what is included under the “special water” or other sensitive receiving waters categories? > Ch. 5, Ch. 10, & App. F
- Select the proper model to use for my unique situation? > Ch. 8 & App. B
- Know what plants to use when I’m planting a rain garden? > App. E
- Make sure everything I need for a particular permit is accounted for? > Ch. 5 & App. G
- Find out what a calcareous fen is and what’s required to protect it? > App. F
- Find out how to maintain a bioretention facility or any other BMP? > Ch. 12
- Find sample/model ordinances? > App. G
- See what sample BMP applications have been done in the state? > Ch. 14
- Identify the potential for ground water/surface water interactions? > Ch. 3
- Minimize the potential for my BMP to breed mosquitoes? > Ch. 6 & Ch. 12
- Incorporate channel protection into my pond outlet design? > Ch. 10
- Identify which MPCA Eco-region I am operating within? > App. A
- Explore more deeply one of the Issue Paper topics that was considered by the Manual Sub-Committee? > App. J
- Find out which watershed (and organization) I am located within? > App. A
- Determine the criteria I need to meet for runoff volume control? > Ch. 5 & Ch. 10
- Quantify my water quality and flood control volume requirements? > Ch. 10
- Maintain my rain garden? > Ch. 12
- Deal with karst geology, tight soils, and potential stormwater hotspots of toxicity? > Ch. 13
- Check that my BMP is suitable based on site conditions or receiving water criteria? > Ch. 7
Overview
Throughout the production of the Manual, one singular goal was kept in mind – to produce a useful product that helps the everyday user better manage stormwater. The purpose, goal, vision and tenets were developed by the original Stormwater Design Team. Although stormwater management to control the pollution of receiving waters has been around in earnest for over 30 years in Minnesota, the advent of many new programs means that guidance is needed more than ever. Such programs as the NPDES (National Pollutant Discharge Elimination System) Phase I and II program, the TMDL (Total Maximum Daily Load) program, and strong runoff control programs at the local and watershed levels have all contributed to the need for this information to be compiled in a comprehensive, technically sound document.
The directive the Manual Sub-Committee received from the SSC was to produce a document that could be used as a single source to guide stormwater managers through the maze of regulations, Best Management Practices (BMPs) designs, models/techniques and terminology that constitute good stormwater management. It does not address the requirements of other non-stormwater related regulatory programs that can have an effect on stormwater. Related to this was the charge to produce a Manual that does not duplicate the many good sources of information already available. Because Minnesota is fortunate enough to have had many additional tools created over the years, the Manual will often forego detailed explanation of a particular element and send the user directly to another resource via electronic linkage or cited reference. These linked resources provide information that Minnesota stormwater managers can put to use in conjunction with this Minnesota Stormwater Manual. The Manual is intended to be flexible, easily updated and responsive to the needs of the Minnesota stormwater community.
The Stormwater Steering Committee members agreed to support this Manual and relay it to the public. Although all members do not agree with all elements or concepts contained in the Manual, they did support release of the Manual as a constructive tool for use by stormwater professionals, regulators, plan reviewers, and the public. Concepts presented in this Manual are intended to be flexible guidance for users rather than stringent rules. Each stormwater problem is different, so solutions will need to be customized to address this variation. This Manual provides the tools, but the user must provide the ingenuity.
This Manual provides direction and guidance for stormwater management in Minnesota. The Stormwater Steering Committee wants you, through your active use of and feedback on the submit Manual, to help Minnesota reach our vision for stormwater management in Minnesota.
The Manual is intended as a guidance document. It will help users identify and appropriately use the best practices to protect Minnesota’s water resources from adverse impacts associated with stormwater runoff. Some practices in the Manual go beyond today’s requirements, and are so identified. Others help to clarify how and when to use currently accepted practices to meet water quality goals. The Manual looks beyond current practices and addresses special situations such as protection of a trout stream or stormwater management in karst areas. Some practices discussed are designed to address unique site conditions and may not be readily adaptable for across-the-board applications.
The Manual does not establish new regulatory requirements and does not supersede existing local, state or federal requirements. Because the Manual combines standard practices with innovative and site specific recommendations, it is strongly recommended that regulators use this Manual only as supporting guidance and not wholly incorporate the Manual by reference in regulatory requirements.
Feedback from users is needed to gauge the Manual’s use and to justify ongoing updates. Case studies on the use and implementation of the Manual recommendations will be particularly useful. Please submit comments and suggested updates based on new technologies, better information, or new studies, to assist us in keeping the Manual accurate and relevant. The Stormwater Steering Committee hopes you find the Manual to be an effective tool in managing stormwater runoff in Minnesota.
Introduction
“Land of 10,000 Lakes” does not capture the abundance of water and water-related resources in the state of Minnesota. Not only is Minnesota the home of more than 10,000 lakes, but there are also some 69,000 miles of rivers and streams, over nine million acres of wetlands, nearly 2,000 miles of trout streams, and ground water aquifers and surface water sources capable of producing drinking water for about four million residents.
The headwaters of the Mississippi River are located in the state and we border the largest freshwater lake in the world, Lake Superior. Protecting, restoring, and maintaining these natural resources, although challenging, must be a priority for all Minnesotans. We all contribute to the contamination that deteriorates our waterways, so it is everyone’s responsibility to minimize these threats and keep our water clean. Protecting the waters of our state plays a huge role in protecting the culture and heritage of our home.
Minnesota’s water and related environment is complex which can, in turn lead to very complicated management systems. As thousands of acres of land are converted annually from rural and open areas to urbanized communities, the impacts on stormwater runoff can become extreme.
With these changes to the surface of the land comes the responsibility of assuring that surrounding waters are not adversely affected. As development escalates, so does runoff. With urbanization, the natural infiltration of water into the ground is reduced. Larger runoff volumes, quicker and higher runoff peaks, and increased erosion are a few of the results that lead to more pollutants eventually making their way to the receiving waters. The challenge for all Minnesotans is to control runoff rate and volume as well as the material that this water picks up on its way to a receiving water.
This Manual explores a variety of management approaches designed to lesson the impacts of development. Although other sources of runoff, such as agriculture and forestry can contribute to water quality deterioration, this Manual focuses on urban sources related to development. Totally eliminating land conversion is not a feasible option, so appropriate and innovative measures must be taken to minimize the negative impact of development. The Manual explores an array of best management practices (BMPs) that can be implemented to control sediment and reduce runoff in a practical and flexible manner on the site. The term “integrated stormwater management” encompasses all aspects of precipitation as it moves from the land surface to the receiving water.
The focus of this Manual is to guide users in such a way that all possible measures are taken to ensure proper, responsible stormwater management. There are many bodies of water in Minnesota that have already been impacted by various pollutants and are in need of improvement. Any water that does not meet the water quality standards established to protect it and deem it usable for its intended purpose is classified by the Minnesota Pollution Control Agency (MPCA) as an “Impaired Water.” The 2004 Minnesota (303d) list of impaired waters contains 1,890 impairments for 1,115 water bodies, many of which are impaired for more than one pollutant. This number is an increase from the 2002 list, and it is anticipated that there will be another increase observed when the April 2006 list is published. This is the result of better data collection that allows for more assessment of where actual impairments are occurring.
There are no proposals for regulatory changes in the Manual; however, there are some recommendations to improve the stormwater standards that are typically used in Minnesota. This was done with the hope of initiating discussions on methods to improve stormwater management, the definition of what constitutes an improvement, and better options for implementing such improvements. As a result of the discussions and input form Minnesota’s stormwater community, there may be the potential at some point to include some of these ideas into regulatory framework.
The intent of the Manual is to promote innovation and generate ideas of new stormwater management practices. Users will also note that this Manual is not an erosion and sediment control handbook, nor is it a BMP manual, although there are features of each within the Manual. Again, users are directed to available resources so that this Manual did not become so long as to be cumbersome and therefore unused.
Finally, the Manual primarily addresses the post-construction requirements of the NPDES MS4 permit program. Elements of the Manual exist for each of the six required Municipal Separate Storm Sewer System (MS4) components and could be used by communities to assist in preparing their permit material. Readers interested in MS4 guidelines are referred to the MPCA web site for the MS4 program.