Buffer Mapping Project

buffer near water

Minnesota's Buffer Protection Map

Buffer Map

Statewide Data Layer

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 will help 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.

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 will the buffer protection map be used?

The map is now ready to be 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 will organize on-site verification of these public water features and will change this temporary label within six months.
  • 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 will notify the DNR. The DNR will make corrections where appropriate and maintain an accurate map. The DNR will release updated maps in October and January.

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

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 preliminary 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 will Public Waters be mapped?

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 will be mapped as a requiring 16.5-foot buffer.
  • Public Water Wetlands that do not have a DNR assigned shoreland classification will not be mapped.


Why aren't all wetlands shown on the buffer map?

Public waters 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 where a landowner thinks he or she has a private ditch, but it's 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

I was never notified that the watercourse, wetland or lake on my private property is public water. Can I challenge a public water designation?

If the waterbody met the definition of public water at the time of the inventory, it is usually not eligible to be removed from the Public Waters Inventory. Proposed changes to the Public Waters Inventory are reviewed on a case-by-case basis. The DNR will correct errors in the Public Waters Inventory maps.

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 was mandatory for both the DNR and the 87 counties of Minnesota. The law established a deadline of December 31, 1982 for the DNR to complete the preparation of a statewide inventory and established a procedure for public review. The law did not require individual landowner notification.


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

Contact your local SWCD. This link leads to an external site. 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 on 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 don't think the watercourse on my land should be a public water.

Review the Frequently Asked Question about Public Waters on this page. Any natural or altered waterway (including ditches) that drained more than two square miles of land that had a definable bed and bank at the time of Public Water Inventory (PWI) designation was considered 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). Contact the DNR Area Hydrologist if you would like to request the DNR to proceed with a review of the public water designation.


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

You should work with the SWCD to determine if the SWCD thinks it is important to change the Buffer Protection Map to reflect your situation. Public watercourses must carry runoff from the upstream watershed for all ranges of flows. The elimination of the low flow channel does not necessarily mean there still isn’t a high flow channel when runoff conditions exceed the tile capacity. You should produce evidence of any permits or permissions obtained to place tile and fill in the low flow channel of the public water and provide additional documentation that demonstrates that runoff does not occur in any remaining high flow channel of the public water. 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.


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.

You should work with the SWCD to determine if the SWCD feels it is important to change the Buffer Protection Map to reflect the altered location on the map. The Buffer Protection Map’s purpose is to inform landowners of which waters need to be buffered, not to show the exact location of the existing water. You 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 low or normal flow channel has moved and high flows still flow through the former public water channel, you may need to buffer both channels.


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.

You should work with the SWCD to determine if the SWCD thinks it is important to change the Buffer Protection Map to reflect your situation. Documentation will be needed to identify how long this condition has existed. 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.


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.


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 (will be mapped as a requiring 16.5-foot buffer).
  • Public Water Wetlands that do not have a DNR assigned shoreland classification (will not be mapped).

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 will work with local SWCD staff for a smooth transition between the required buffer widths.

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.


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.