Buffer Mapping Project

buffer near water

Minnesota's Buffer Protection Map

Minnesota's buffer law establishes new perennial vegetation buffers of up to 50 feet along rivers, streams and ditches that will help filter out phosphorus, nitrogen and sediment. The law provides flexibility and financial support for landowners to install and maintain buffers.

The DNR's role in Minnesota's buffer law is to produce and maintain a map of public waters and public ditch systems that require permanent vegetation buffers. The DNR released the buffer protection map in July 2016. The map is helping to guide the implementation of Minnesota's buffer law by landowners, with the help of the Board of Water and Soil Resources (BWSR), Soil and Water Conservation Districts (SWCDs), Drainage Authorities and other local governments.

Buffer Map

Statewide Data Layer

How was the map made?

With the help of a wide range of professionals inside and outside the agency, the DNR combined existing public water inventory data, shoreland classification data and public ditch data to produce the map. The DNR used an extensive public and professional review process to produce the map.

How is buffer protection map being used?

The map is now being used for implementation. It helps landowners determine where buffers or alternative water quality practices are required and what buffer widths are required.

  • The map labels public ditches as requiring a 16.5-foot buffer (local ordinances may require wider buffers).
  • The map labels public waters as requiring a 50-foot average buffer (local ordinances may require wider buffers).
  • The map also labels a few sites as "needing field review." The DNR is organizing on-site verification of these public water features and will change this temporary label as they are verified.
  • The DNR excluded some public water wetlands from the map.

Local SWCDs are working with landowners to create the right size buffer or select an alternative water quality practice. If the SWCDs, Drainage Authorities or other local governments identify errors in the map during landowner conversations, they notify the DNR. The DNR is making corrections where appropriate and will maintain an accurate map. The DNR last updated the buffer protection map in August 2017.

The DNR wants to thank all the individuals and organizations that helped us produce the map, with special thanks to those landowners and organizations that are going beyond the minimum buffer requirement to protect one of our most important natural resources: water.

Additional Resources

Guidance on Buffer and Shoreland Ordinances

Guidance on model ordinance language developed by BWSR and DNR is available.

Board of Water and Soil Resources

2015 Buffer Legislation provides information on implementation of the buffer law.

Soil and Water Conservation Districts

To suggest a correction to the buffer map, contact your local Soil and Water Conservation District. SWCDs are able to work directly with landowners on these issues.

Common Buffer Questions

Click on questions below to show answers. Click again to hide.

What are Public Waters?

Public waters are all lakes, wetlands and watercourses that meet the criteria set forth in Minnesota Statutes 103G.005, subd. 15 and are designated on public waters inventory maps.

How are Public Waters mapped?

All Public Waters are mapped as requiring a 50-foot buffer, with two exceptions:

  • Public Water Watercourses that are also a Public Ditch and do not have a DNR assigned shoreland classification are mapped as a requiring 16.5-foot buffer.
  • Public Water Wetlands that do not have a DNR assigned shoreland classification are not mapped.
Why aren't all wetlands shown on the buffer map?

Public water wetlands include all type 3, 4, and 5 wetlands (as defined in U.S. Fish and Wildlife Service Circular No. 39, 1971 edition) that at the time of designation were 10 acres or more in rural areas or 2-1/2 acres or more in cities and are designated on the DNR’s public waters inventory. Wetlands not meeting this definition are not displayed on the map viewer, as they are not specifically addressed in the 2015 buffer law. Additionally, the DNR has determined that public water wetlands without a shoreland classification do not have hydrological conditions that make mandatory buffers practical. For those reasons, the map does not depict many public water wetlands as requiring a buffer.

Does the clarification bill make it clear that private ditches are exempt from the new buffer law?

It does. However, there may be cases in which what a landowner thinks is a private ditch is actually a public water. In relation to the buffer law, the term "public water" means waters that are on the DNR public water inventory map, which can be viewed here.

Landowner Questions

What are public waters and how were they designated?

In 1979, the DNR was directed by the Minnesota Legislature to prepare and maintain a public waters inventory (PWI) map ''...for each county that shows the waters of this state that are designated as public water under the public waters inventory and classification procedures." (Minn. Stat. 103G.201 and Minn. Laws 1979, Ch. 199).

Following that 1979 legislative directive, public waters were designated in the 1980s through a legal process that included a DNR inventory and a county-led public review and appeal process. Public waters and the public waters inventory process were defined in Laws of Minnesota 1979, Chapter 199. Under this law, the inventory and review process were mandatory for both the DNR and the 87 counties of Minnesota. The law established a deadline of December 31, 1982 for DNR to complete the preparation of a statewide inventory and establish a procedure for public review. The law did not require individual landowner notification.?DNR worked with the counties and through local media to ensure the inventory was widely publicized and landowners understood the review and appeal process. The county-led meetings were well-attended and many landowners did challenge the inclusion of specific waterbodies and watercourses in the inventory.

The statutory definition of public waters (Minn. Stat. 103G.005, subd. 15(a)(9)) includes lakes, certain wetlands, and natural and altered watercourses with a total drainage area greater than two square miles. An altered watercourse is a former natural watercourse that has been altered artificially to straighten, deepen, narrow, or widen the original channel. Alteration of a natural watercourse is, by itself, not a basis for exclusion from the PWI.

Some public watercourses have been altered and used as drainage ditches by landowners, and are not part of a public drainage system. The fact that the public water is used as a private ditch system does not change the watercourse designation; it is still a public water. The Legislature expressly rejected public ownership as a requirement for designation of public waters under Minnesota law. (Minn. Stat. 103G.005, subd. 15 and Minn. Laws 1979, Ch.199, 2: "The public character of waters shall not be determined exclusively by the proprietorship of the underlying, overlying, or surrounding land...").

How are changes made to the Public Waters Inventory?

The DNR has very limited authority to make changes to the public waters inventory. The applicable statutory provision for responding to public change requests is Minn. Stat. 103G.201 (e)(2)(i), which authorizes the DNR to revise the public waters inventory map for each county "...as needed to correct errors in the original inventory."

Proposed changes to the public waters inventory are reviewed on a case-by-case basis.

Any natural or altered waterway (including ditches) that drained more than two square miles of land and that had a definable bed and bank at the time of PWI designation was inventoried as a public water. This designation cannot be removed unless it can be proven to have been in error at the time of designation (late 1970s through early 1980s).

Anyone who wants to challenge inclusion of a watercourse segment in the public waters inventory should provide documentation that the watercourse in question did not meet the definition of a public water at the time of the inventory. This information should be submitted to DNR’s area hydrologist (Area Hydrologist Contacts), along with a request to remove the watercourse segment from the public waters inventory.

DNR will review the information provided, along with information from our public waters designation files and other relevant information (e.g., aerial photographs, USGS maps, original land survey information). We will determine if the public watercourse segment being challenged was designated in error.

If we determine the watercourse segment was designated in error we will remove it from the public water inventory and buffer protection map. If we determine it was correctly designated a public water, it will remain in the public water inventory and on the buffer protection map. Those who request removal of waters from the public waters inventory will be informed of DNR’s decision and will be given our reasons for the decision.

I understand buffer requirements on the map, but I want technical assistance about buffer requirements on my land.

Contact your local SWCD. They will help you understand exactly what you need to do to install buffers or alternative water quality practices on your land.

I am uncertain whether my waterway requires a buffer when viewing the map.

Contact the SWCD for assistance or clarification. If the map needs a correction, the SWCD can request a change to the map. If the SWCD needs assistance with the question, they will contact the DNR for further clarification as needed.

I have a question about a public ditch designation on the map.

Contact the appropriate Drainage Authority for clarification. This will often be your county but could be the local watershed district if one exists in your area. If a change in the map is warranted, the Drainage Authority will contact the DNR to request the change.

I believe the public ditch going through my land should require a 16.5-foot buffer and not a 50-foot buffer.

Review the DNR criteria used for the creation of the Buffer Protection Map, found in the Map Criteria FAQ below. Only public ditches having no specific DNR shoreland classification were given a 16.5-foot buffer width. All other public waters on the Buffer Protection Map have a 50-foot buffer requirement, including public ditches where a specific shoreland classification was assigned. If you believe there is no shoreland classification that meets these requirements, please contact your Area Hydrologist, who can do a further review.

I (or a previous landowner) placed tile in the bed of the public watercourse, so a buffer should not be required.

Public watercourses must carry runoff from a sizable upstream watershed for all ranges of weather conditions. While the tile may have eliminated overland water flow under drier conditions, runoff during wetter conditions may exceed the tile's capacity. Landowners should provide their area hydrologist with evidence of any permits or permissions obtained to place tile and fill in the channel of the public water and provide additional documentation that demonstrates that runoff does not occur in any weather conditions. The DNR may remove the watercourse from the Buffer Protection Map with satisfactory documentation. If a buffer is required, working with your SWCD on an alternative water quality practice plan may provide better water quality treatment than a buffer in some situations. If the SWCDs, Drainage Authorities or other local governments identify errors in the map during landowner conversations, they will notify the DNR. The DNR will make corrections where appropriate and will maintain an accurate map.

The public drainage system on my land has been tiled where the public water used to be, so a buffer should not be required.

You should contact the Drainage Authority. The Drainage Authority-authorized representative can provide documentation to the DNR about permissions obtained to tile and place fill in the public watercourse. The Drainage Authority can request the DNR to remove the buffer requirement, if they provide documentation that runoff does not occur in any remaining high flow channel of the public ditch.

An act of nature, previous landowner or I have moved the public watercourse to a different location than depicted on the PWI map and I believe the Buffer Protection Map is in error for the location of the buffer.

The Buffer Protection Map’s purpose is to inform landowners of which waters require buffers, not to show the exact location of the existing water. Landowners should provide the DNR with documentation of a permit or permission received to relocate the public watercourse to a new location, if that is how the watercourse was relocated. If only the water flow under low or normal weather conditions has been moved, and the water flow under wetter conditions still follows the former public water channel, you may need to buffer both channels. If the SWCDs, Drainage Authorities or other local governments identify errors in the map during landowner conversations, they will notify the DNR. The DNR will make corrections where appropriate and will maintain an accurate map.

There is no channel where the public water is shown. I am farming through the area or it is a grassed waterway and a buffer requirement is not reasonable.

Documentation will be needed to identify how long this condition has existed. Changes to the course, current or cross-section of a public watercourse would require a DNR permit. Please provide documentation of any permits obtained to allow farming through the public watercourse. The DNR will review any input by the SWCD for erosion and runoff pollution risk or excessive soil loss considerations, in order to make a more informed decision about the buffer requirement. In general, the DNR would encourage consideration of alternative water quality practices (check with the SWCD or BWSR) that would meet the intent of the law, instead of removal of the segment from the Buffer Protection Map. If the SWCDs, Drainage Authorities or other local governments identify errors in the map during landowner conversations, they will notify the DNR. The DNR will make corrections where appropriate and will maintain an accurate map.

The Drainage Authority believes the Buffer Protection Map is in error, or has amendments to the map as a result of a redetermination of benefits or improvement proceeding.

The authorized representative of the Drainage Authority should use the DNR registered user application tool and upload the new data to reflect changes to the map. If the changes involve an underlying designated public watercourse (altered or natural channel), please contact the appropriate DNR Area Hydrologist to coordinate the requested change in designation.

Why aren't all change requests reflected in the Buffer Map?

The DNR received nearly 4,500 change requests from registered users of the Buffer Mapping Tool by early August 2017. All of those requests were reviewed and 2,961 of them were incorporated into the buffer protection map. Change requests that meet the specific criteria of the buffer mapping project are implemented in the buffer map.

The DNR systematically reviews all comments from registered users and accepts changes that are consistent with the map purpose and criteria. The DNR will continue to review comments entered in the Buffer Mapping Tool by registered users and will update the map with accepted changes. The Buffer Mapping Tool also now provides the decision and rationale for every change request received, whether accepted or not.

What if I disagree with the decision the DNR made on my buffer map comment?

If the DNR does not agree with your suggested change to the buffer map, you can request a second review.  Please contact your local Area Hydrologist to discuss your concern.  If necessary, an on-site visit can be arranged with Soil and Water Conservation District and DNR field staff to address your concerns.

The map viewer shows road ditches bordering or crossing my property. Will buffers be required along road ditches?

Permanent buffers are required along road ditches if those ditches are: 1) a public water, or 2) part of a public drainage system.

Riparian buffer zones are also required when construction projects take place near “special” waters as defined in the Minnesota Pollution Control Agency’s construction stormwater general permit. These waters include trout streams, trout lakes, fens and more.

Map Criteria

Why does the location or boundary representing a lake, wetland or stream in the map viewer not match what is shown on the aerial photograph? Which information takes precedence?

Buffers should be installed adjacent to the actual water feature.

The public waters inventory maps were created in the late 1970s and early 1980s using paper base maps with a less precise scale than is possible with the internet-based map viewer now being used. The mapped location or boundary of a public water lake, wetland or stream may not align exactly with the actual location or boundary. The stream lines on the map viewer may not match the actual location of the stream, because the stream may have changed course over time. The change in the stream location may have occurred naturally or by human alteration.

How is it determined whether a watercourse is required to have an average 50-foot buffer or a 16.5-foot buffer?

The DNR has developed criteria for buffer width requirements shown on the buffer map. The criteria incorporate public waters inventory, public ditch and shoreland classification information. The 2015 buffer law (103F.48, Subd. 3 (a) (1)) specified that vegetative buffers with a minimum width of 30 feet and an average of 50 feet are required on public waters, unless state shoreland standards under 103F.211 are more restrictive. The 2015 buffer law also requires 16.5-foot buffers along all Chapter 103E public drainage ditches.

All Public Waters will be mapped as requiring a 50-foot buffer, with two exceptions:

  • Public Water Watercourses that are also a Public Ditch and do not have a DNR-assigned shoreland classification (are mapped as requiring a 16.5-foot buffer).
  • Public Water Wetlands that do not have a DNR-assigned shoreland classification (are not mapped).

Please note: For purposes of the Buffer Protection Map, altered natural watercourses that are part of a public drainage system and have been assigned a shoreland class of 'tributary' in local shoreland ordinances require a buffer of 16.5 feet. Please consult with your local shoreland ordinance administrator for requirements that exceed the buffer law.

State shoreland rules have included requirements for buffers prior to the 2015 buffer law. Shoreland rules apply to all public waters to which the DNR has assigned a shoreland classification and are subject to local shoreland ordinances. Some public ditches are assigned a DNR shoreland classification and will continue to be subject to buffer requirements in local ordinances. The DNR is working with local SWCD staff for a smooth transition between the required buffer widths.

The watercourse shown on the viewer only has water in it a few times a year. What requirements apply?

If the watercourse is a public water or part of public drainage system, a buffer or alternative riparian water quality practice is required.

Watercourses with intermittent flows still serve important ecological and water quality functions, especially in the upper reaches of watersheds. Groundwater recharge areas, ephemeral channels and other areas where runoff collects are important areas to buffer, in order to prevent erosion and soil loss and help protect or provide riparian corridors.

Why doesn't the buffer protection map show buffer widths according to local shoreland ordinances?

The buffer protection map only shows the minimum state buffers as required by the buffer law. Buffer requirements in local shoreland ordinances sometimes differ from requirements of the buffer law, specifically in relation to state shoreland classifications. Landowners must comply with any local shoreland ordinance requiring wider or longer buffers than the minimum state standard shown on the buffer map.

How were state shoreland classifications used to determine buffer widths in the buffer protection map?

For the most part, state shoreland classifications were not a determining factor for buffer widths on the buffer protection map, except for two instances:

  1. public water watercourses that are also public ditches and that have a specific shoreland classification assigned by the DNR, and
  2. public water wetlands.

The DNR assigned a specific* shoreland classification to most main stem public water watercourses in the state, some of which contain public ditch segments. On the buffer protection map, these watercourses (including their ditched segments) are assigned a 50-foot average minimum buffer because they have a specific shoreland classification and the state shoreland standards and criteria apply pursuant to the buffer law. Alternatively, public water watercourses that are also public ditches but do not have a specific DNR-assigned shoreland classification are assigned a 16.5-foot buffer.

Public water wetlands that do not have a DNR-assigned shoreland classification are mapped as not requiring buffers because they are small, shallow wetlands with shorelines that can fluctuate quite a bit from year to year, typically have a vegetative fringe, and the beds of these wetlands can be and are farmed in dry years.

*Refer to Minnesota Rules, part 6120.300, Subp. 1a. (A) - (H) for the "specific" state shoreland classifications.

Why are there differences between state shoreland classifications and local shoreland classifications?

In the 1970s and again in the late 1980s/early 1990s, the DNR undertook formal processes to assign shoreland classifications to all public water basins and watercourses in accordance with the statewide Shoreland Rules (6120.3000, Subps. 1-3). These shoreland classifications were communicated to local governments in the form of shoreland classification lists and were incorporated into local shoreland ordinances. Local governments can formally request changes to the shoreland classifications of public waters within their jurisdiction by submitting a resolution and supporting data under the statewide Shoreland Rules (6120.3000, Subp. 4). When a local government formally requests a change in classification and the DNR approves it, the public water is reclassified.

 Over time, many local governments have amended their shoreland ordinances to change the classifications applied to public waters in their jurisdiction. They typically do this to apply higher standards or to better accommodate areas of existing development on specific public water basins or watercourses, which is allowed under shoreland statutes and rule. Some local governments that made these ordinance amendments submitted their ordinances to the DNR for review and approval as required by law, and some did not. In either case, if a local government did not submit a formal resolution with supporting data to change the shoreland classifications, the public water was not reclassified. DNR approval of a local shoreland ordinance amendment does not automatically result in a change to the state shoreland classification; the two actions require separate DNR approval requests and review processes. As a result, the state shoreland classifications for some public waters differ from those in local shoreland ordinances.

The DNR is willing to work with local governments to formally reclassify public waters to match those in their shoreland ordinances. When changes to shoreland classification are approved, the state buffer map will be updated accordingly.

If my community has more stringent buffer requirements in its local shoreland ordinance than those shown on the map, which applies.

The buffer map represents the minimum state riparian buffer protection standards described in the buffer law (MN Statute 103F.48). Landowners must comply with any local ordinances that are more restrictive than the buffer law.

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