Chapter 5 presents a compilation of Best Management Practices (BMPs) that are specifically applicable to public drainage systems in Minnesota. The chapter and its contents support the work of ditch authorities, their staff and engineers by providing guidance and tools to address design, maintenance, repair, and water quality and quantity issues on and in the watershed of Minn. Stat. 103E drainage systems.
Chapter 5 provides a resource for users with varied levels of experience using BMPs on Minn. Stat. Chapter 103E systems. Reference to relevant statutes, a BMP Table, and BMP definitions are provided.
The BMPs provided support Minn. Stat. Chapter 103E Drainage Law in two (2) primary ways:
For the purposes of this manual, a BMP is a structural or non-structural practice that minimizes water quality and/or quantity (peak flow or volume reduction) impacts within a public drainage system or its watershed.
There are two (2) types of BMPs:
On-system BMPs are used within a Chapter 103E drainage system and include any statute-allowed, or required practice (i.e., vegetated buffer strips, grade control structures, side inlets, erosion control, multi-stage ditch, water storage, restored wetland, culvert sizing, resloping, tile repair, etc.). Many of such practices do not have a design standard.
BMPs implemented off the Chapter 103E drainage system are not within the traditional purview of the drainage authority. Practices applied on fields and farms in the watershed of system can provide significant benefits downslope to the drainage system. Drainage inspectors and drainage system engineers should be aware of the potential for off-system BMPs to solve on-system problems.
Other resources from which the BMPs provided within this chapter are also cited include (Chapter 5, Section I, E):
The suggested method for navigating through the BMP identification process and how to use Chapter 5 includes three (3) steps (Chapter 5, Section I, F):
The purpose of this chapter is to provide a compilation of BMP information specifically tailored to public drainage systems in Minnesota. The chapter supports the work of ditch authorities, their staff and engineers by providing guidance and tools to address design, maintenance, repair, and water quality and quantity issues on and in the watershed of Minn. Stat. 103E drainage systems.
Soon after it was established in 2005, the Stakeholder Drainage Work Group (DWG) recommended the inclusion of a Best Management Practices Chapter in the updated Minnesota Public Drainage Manual (MPDM). The addition of what is now the new Chapter 5 – Public Drainage System Best Management Practices has been a part of a number of MPDM Update funding requests dating back to early 2007. The 2013 appropriation language providing funding for the update of the MPDM specifically required the inclusion of the BMP chapter.
The BMP chapter was first envisioned by the DWG as a guide to inspectors and engineers for drainage system maintenance and repair work. However, the scope of the chapter has been expanded to support potential BMP implementation related to recent changes to Minn. Stat. 103E.015, Considerations Before Drainage Work is Done, Subdivision 1. Environmental, land use, and multipurpose water management criteria. (Refer to Chapter 3 for a full discussion of Minn. Stat. § 103E.015.)
While there are few requirements in Drainage Law that necessitate drainage authorities’ use of specific BMPs in their administration of Minn. Stat. 103E drainage systems, BMPs can improve the function and stability of the system for drainage purposes, as well as support the environmentally effective application of drainage law. The BMPs provided in this chapter support Chapter 103E Drainage Law in two primary ways.
First, the BMPs presented in this chapter provide information and support for drainage authorities work through the drainage system design and construction considerations required by the following Statute:
These changes resulted in the requirement of “consideration” of multipurpose water management criteria. The full list of environmental, land use, and multipurpose water management criteria as listed in Minn. Stat. § 103E.015 Subd. 1 are presented in Chapter 3 of the Minnesota Public Drainage Manual. Consideration of these criteria ensures that BMPs are evaluated during the planning and design of a drainage project (as defined in Minn. Stat. § 103E.005, Subd 11).
Second, the BMPs presented in this chapter supplement and enhance drainage system repair, maintenance, and management activities addressed by the following Statutes:
Note: During the 2015 Special Legislative Session, Governor Dayton signed into law Minn. Stat. § 103F.48 that requires buffers to be established on all public drainage ditches by landowners no later than November 2018. Public ditch buffers placed under this statute only become 103E buffers if and when the drainage authority makes them a part of the drainage system by paying damages. Until then the landowner will be required to maintain the buffers.
In this manual, a Best Management Practice (BMP) is a structural or non-structural practice that minimizes water quality and/or quantity (peak flow or volume reduction) impacts within a public drainage system or its watershed and/or downstream.
BMPs are of two types: on-system and off-system.
On-system BMPs are used within a Minn. Stat. Chapter 103E drainage system and are aligned with the statute based authorities and responsibilities of the drainage authority. These can include any statute-allowed, or required practice, i.e. vegetated buffer strips, grade control structures, side inlets, erosion control, multi-stage ditch, water storage, restored wetland, culvert sizing, resloping, tile repair, etc. Many of the on-system practices do not have a design standard.
Other BMPs are located off the Minn. Stat. 103E drainage system, and consequently, not within the traditional purview of the drainage authority. However, as a result of efforts related to Minn. Stat. § 103E.015, a drainage authority may find that there are practices that can be applied on fields and farms in the watershed of the system which will provide significant benefits downslope to the drainage system. Typical structural off-system BMPs might include water and sediment control basins, grass waterways, and Drainage Water Management (DWM) to name a few. Typical non-structural off-system BMPs would be nutrient management, cover crops, and conservation tillage, etc. that are applied on lands within the watershed of the system. It is important for both the drainage inspector and the drainage system engineer to become aware of the potential for off-system BMPs to solve on-system problems.
The BMPs covered in the BMP Table include many BMPs associated with public drainage systems in Minnesota.
Temporary construction stormwater BMPs used during construction activities are not covered explicitly. BMPs for temporary construction-related erosion and sediment control and stormwater management can be found on the Minnesota Stormwater Manual website, managed by the MN Pollution Control Agency.
Further information about a few on-system BMPs and many well-documented standards for off-system BMPs can be found in the USDA’s FOTG and Minnesota Department of Agriculture’s Ag BMP Handbook for Minnesota (published in 2012 and presently undergoing its first update (available in early 2017)).
The NRCS Engineering Field Handbook – Part 650 of the NRCS National Engineering Handbook – provides information and design guidance on how to utilize the BMP specifications contained in the FOTG.
Culvert sizing is presented in .
On existing public drainage systems, look for symptoms or potential indications of a problem through the use of field observations, inspector or engineer’s reports, studies, local water plans (see note below) or strategies defining what is happening in the watershed of the public drainage system.On new public drainage system establishments, professional judgment is required to site BMP to minimize any adverse impacts. Lessons learned from experience with other drainage systems should be considered in the design of the new system.
Problems/symptoms are the physical issues identified along a public drainage system.
Examples might include:
While investigating Sources of External Funding per Minn. Stat. § 103E.015, Subd. 1a., a drainage authority may find that funding is available through a local water planning organization, state or federal agency, or other entity to accomplish multipurpose water management practices to benefit a drainage system while benefiting downstream water resources and landowners. An example of such an opportunity might be finding a landowner that desires to place a grassed waterway in the watershed of a drainage system that is experiencing extensive sedimentation from field erosion.
Note: Local water management plans are created and maintained by local government units that have responsibility to protect and improve local water resources. The intent of each local water plan is to guide management of water resources for multiple purposes. When the plan is implemented through any LGU, drainage authority (in the present case) or landowner, another step is taken in multipurpose water management within the jurisdiction of the planning organization. Such a focus benefits not only local water resources, but also downstream waters in Minnesota and in due course water bodies downstream of Minnesota, such as the Gulf of Mexico and Lake Winnipeg.
In order to select an appropriate BMP or BMPs, the causes of the problem must be considered. Causes are the underlying root or roots to the symptoms/problems identified along the system, or immediately upstream or downstream of the legal public drainage system.
Examples might include:
Note: Watershed Restoration and Protection Strategies, Stressor Identification Reports, and One Watershed One Plan reports can be useful in this step in helping to identify the contributing factor(s) or cause(s) of the problem(s).
A solution in the BMP Table is a BMP or suite of BMPs that together address a problem/symptom or address the cause. In general, an attempt to address the cause is preferred.
Note: The designer will want to consider whether to treat the symptom or the cause of the problem. In some cases, it may be necessary to only address the symptom when a larger more complex (and potentially more costly) project may be needed to address the determined cause(s). Professional judgment must be used in the selection of an appropriate BMP given site specific conditions.
BMPs are organized into the BMP Table by problems/symptoms and causes. A listing of potential BMP solutions are provided for each problem/cause. The user will enter the BMP Table using the problem/symptoms/causes determined in Steps 1 and 2 to identify a potential BMP(s).