Summer 2017 Water Talk

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Water Talk Newsletter - Summer 2017

July 5, 2017

In This Issue

Water Talk Newsletter is issued three to four times per year.

If you have ideas or requests for the next edition of Water Talk, contact Ceil Strauss at

Buffer Law & Shoreland Ordinances

Ditch with grass buffer

Both the riparian buffer law (Minnesota Statutes, § 103F.48) and the shoreland rules (Minnesota Rules, part 6120.3300, subp. 7) address buffers on public waters. Both laws regulate buffer widths and conservation plans/alternative practices through somewhat different language.  In order to eliminate potential confusion over these two sets of regulations and to be consistent with the buffer law, a number of counties have amended or are considering amending the agricultural provisions in their shoreland ordinances. Here are some important considerations for counties who may be considering amending their shoreland ordinances.

For counties taking on buffer law enforcement authority

Counties electing buffer law jurisdiction should keep ordinance provisions related to the buffer law and shoreland act separate and distinct to minimize administrative confusion and to expedite review and approval time. Although related, the buffer law and shoreland act are two separate statutes with different purposes and state agency regulatory authorities. BWSR has developed model buffer ordinance language and it will be posted on their website soon. BWSR will be reviewing county ordinances that enforce the buffer law, and the DNR will continue to review and approve amendments to shoreland ordinances.

For counties that chose to enforce the 50 foot average/30 foot minimum buffer standard in the buffer law instead of the 50 foot minimum in the shoreland rules, amending the shoreland ordinance for consistency with the buffer law and related county buffer ordinance is recommended to alleviate confusion over which standard applies. The DNR finds such an amendment to be substantially compliant with the statewide shoreland rules. The DNR has developed a guidance document with model language and procedures for updating the buffer-related provisions in a local shoreland ordinance. This guidance document will be available on the DNR website soon. In the meantime, contact your DNR Area Hydrologist for more information.

For counties not taking on buffer law enforcement authority

Counties not electing buffer law jurisdiction are still responsible for enforcing their shoreland ordinance, including the agricultural buffer requirement. These counties do not need to adopt a buffer ordinance and do not need to amend their shoreland ordinance. To alleviate potential confusion over varying standards in different laws, however, counties may want to amend their shoreland ordinance for consistency. In these cases, counties should work with their Soil and Water Conservation District (SWCD) and the entity taking on enforcement (watershed district and/or BWSR) to clarify which width will be enforced. The county may consider amending the 50 foot minimum agricultural buffer requirement in its shoreland ordinance to be consistent with the 50 foot average/30 foot minimum standard in the buffer law using the DNR’s model ordinance language referred to above.

Ditch with longer grass buffer

All shoreland ordinances and amendments thereto must be reviewed and approved by the DNR. The DNR will work with counties to quickly review and approve changes to their shoreland ordinance if the changes are consistent with the DNR’s model language. The DNR generally will not approve amendments that cross-reference and/or mix and match buffer law and shoreland ordinance requirements. These types of amendments can create confusion and potentially weaken shoreland ordinances over time given the long-term uncertainty of the buffer law.

Communities can check the BWSR website for more information, and contact their DNR area hydrologist with any questions regarding shoreland ordinance amendments. Counties considering amendments should contact their area hydrologist as early in the amendment process as possible.

Recent Wisconsin Supreme Court Decision

U.S. supreme court decision 1st page

Breaking News

The U.S. Supreme Court ruled June 23, 2017 on a case involving landowners on the St. Croix River in St. Croix County, Wisconsin. The court ruled in favor of the State of Wisconsin et al. on a regulatory takings case.

See Murr v. Wisconsin for more details.

MnDNR will be evaluating this decision and will include an article on how the facts of this case and the ruling relate to Minnesota laws in the next issue of Water Talk.

New Address for Paper Letters of Map Change

Paper Submittals

As of March 20, 2017, any paper Letter of Map Change (LOMC) requests (including Letters of Map Amendments - LOMAs) or additional data submittals for requests in progress sent via U.S. or express mail should be sent to:

LOMC Clearinghouse

3601 Eisenhower Avenue, Suite 500

Alexandria, VA 22304-6426

Online Submittals

Online LOMC map

Remember that new LOMC requests can be submitted electronically. This can expedite the process relative to paper submittals.

For details and to gain access to the Online LOMC tool, visit the FEMA website at 

DNR Releases New Shoreland Model Ordinance

The DNR has released a new shoreland model ordinance to help counties and cities develop shoreland ordinances or update existing ordinances consistent with Minnesota’s Shoreland Rules (6120.2500 - 6120.3900). While the shoreland rules have not changed since 1989, the new model includes a number of improvements over the original 1989 model ordinance:

  • Consistency with Statutes. Since 1989, statutes dealing with variances, nonconformities and agricultural buffers have changed. The new model includes language consistent with these statutory changes.
  • Consistency with Rules. Over the same period, other state agency rules dealing with feedlots, septic systems, wetlands and environmental review have also changed. These changes have been integrated into the model’s performance standards.
  • Plain Language. The model has been rewritten and reorganized with plain language. Long paragraphs of text have been shortened and replaced with numbered lists, redundant language has been eliminated and graphics have been introduced to illustrate key definitions and dimensional standards. 
  • Improved Design & Provision Explanations. The model includes two documents. The commentary document provides a line-by-line explanation of many required provisions as well as optional provisions for better administration and resource management. The second is an MS Word document that only contains the model language for cutting and pasting.

Dan Petrik, DNR land use specialist, said “the DNR will update the model ordinance periodically, based on user feedback and to maintain consistency with related statutes and rules.”

The state shoreland rules and local shoreland ordinances guide shoreland development to minimize impacts to habitat and water quality. 

Definition of shoreland graphic

Shoreland is the area within 1,000 feet of a lake edge and 300 feet from a river bank or the outer edge of a floodplain, whichever is greater.


                  Figure 1: Shoreland District definition graphic

Adopting a shoreland ordinance is recommended as a “Best Practice Action” to improve surface water quality under the Minnesota GreenStep Cities Program. Minnesota Statute 103F.221 requires cities containing shoreland to submit ordinances to the DNR to review for compliance with the shoreland rules. Minnesota Statue 414.033 also requires cities to adopt a shoreland ordinance for annexed land containing shoreland.

The new shoreland model ordinance includes a full array of zoning and subdivision regulations for most shoreland management situations. The DNR will approve local shoreland ordinances that contain all the provisions in the model ordinance. However, it is anticipated that many ordinances will deviate from the model to address historical development patterns and specific local water resources. Many model ordinance provisions may duplicate language already in another ordinance section, while some provisions may not be applicable, depending on how counties and cities manage certain land uses.

The model ordinance documents can be downloaded from the DNR website.

Please contact your DNR Area Hydrologist  with questions about the model ordinance or the process for getting DNR approval of a shoreland ordinance or amendment.

Zoning Challenge - Site in Mapped Floodplain is Actually Above the Base Flood Elevation

Site location on Flood Insurance Rate Map

You are asked about a site that is clearly within the Special Flood Hazard Area (SFHA) in a Zone AE on the current effective Flood Insurance Rate Map (FIRM).

(See clip from the current effective FIRM in figure to the left.)

The base flood elevation (BFE) is between 636 and 637' NGVD on the current effective map.

The landowner wants to construct a new shed.


Elevation contours in site area


You look at the two-foot elevation contours at the proposed building site and see it is above the 640' NAVD88 contour.

(See example of two-foot contours overlaid on aerial to the right.)


Houston preliminary new FEMA map clip



The county has a preliminary new FEMA countywide FIRM. The preliminary new map shows BFEs of 635.4' NAVD88 to the north (at cross section G) and 635' NAVD88 to the south (at cross section F).

On the new preliminary FIRM the site is shown in the lower risk Zone X.

Elevation information notes:

1. The conversion between NGVD29 and NAVD88 is 0.0 feet in this area. Normally it is important to convert elevations in one datum to be consistent with the other datum. (In some parts of Minnesota there is a 1.4 foot difference!)

2. Many communities have this elevation layer on their GIS systems. If you are in Minnesota these elevations can also be seen on the MnTOPO viewer. To learn more, see "Using MnDNR's MnTOPO Site" article at the bottom of this Water Talk issue. 

Questions from the local official:

  1. Can we issue a permit, or do we need to wait for new effective maps?
  2. Is the mandatory flood insurance still in effect?
  3. Can we use the base flood elevations (BFEs) on the new preliminary maps?

See answer at bottom of this newsletter.

Graphics source for this article: Houston County, MN

Solar Facilities in Shorelands - DNR Guidance

Guidance Applicability

Solar panels in field of wild flowers


This guidance applies to facilities generating solar power intended for off-site use. These include solar gardens (consistent with Minn. Statutes 216B.1641), solar farms, and utility scale facilities.

These are principal uses. Under Minn. Statutes, §216E, facilities generating 50 MW or more require environmental review and a permit from the Public Utilities Commission. Projects generating between 25 MW and 50 MW require environmental review and typically need a conditional use permit from the local government. Solar facilities generating between 5 MW and 25 are subject to discretionary review (Minn. Rules 4410.4500). Because of their smaller size (1- 5 MWs), solar gardens are reviewed and permitted by local government.

This guidance does not apply to facilities designed to provide power primarily for the on-site primary use but where excess power may be sold back to the grid. This type of on-site power generation is considered an accessory use and should be regulated through a local zoning ordinance and permit.

See model solar ordinance for ideas on how to regulate these facilities. These facilities must also comply with applicable shoreland rule (Minn. Rules 6120.2500 – 6120.3900) provisions in local zoning ordinances – See Item #3 below.

Natural Resource Considerations

Given the many positive benefits of using the sun’s energy as a sustainable source of power, there are a number of natural resource considerations in siting solar power facilities in shorelands and other sensitive natural resource areas. Solar power facilities, or “photovoltaic generating sites,” require a large footprint and in some circumstances can have significant impacts to natural resources. In the big picture, it is not sustainable to replace existing natural areas with power generating facilities.   Solar projects should be sited in the least environmentally damaging locations where prior disturbance has already occurred.  In Minnesota, a majority of the commercial solar sites have been located in agricultural fields, prior mined sites, and in areas with low quality habitat.  Developing solar sites in wetlands, native prairie, or rare species habitat should be avoided.  The shoreland rules were developed in 1989, long before solar power became a feasible energy source, and thus do not directly address this land use. The following guidance is provided for communities exploring how to address solar facilities in shorelands.

Shoreland Rule Requirements that are Applicable to Solar Power Facilities and Structures

1.       Prohibit on Natural Environment Lakes and Remote, Transitional, and Agricultural River. The shoreland rules prohibit industrial uses in the shoreland of lakes and rivers with these shoreland classifications (Minn. Rules 6120.3200 Subparts 4 and 5).  Solar power generation fits within the shoreland rule definition of industrial use (Minn. Rules 6120.2500 Subp. 7b) – “the use of land or buildings for the production, manufacture, warehousing, storage, or transfer of goods, products, commodities, or other wholesales items.” Communities can either apply this interpretation in administering their existing shoreland ordinances, or, if they want more clarity, can amend their ordinances by adding a specific prohibition of solar power facilities.

2.     Allow as a Conditional Use on General Development and Recreational Development Lakes, and Urban, Forested, and Tributary Rivers. The shoreland rules only allow industrial uses as conditional uses in the shoreland of lakes and rivers with these shoreland classifications (Minn. Rules 6120.3200 Subparts 4 and 5). Before deciding to allow solar facilities as a conditional use in these areas, communities should evaluate the impact of solar power facilities in each shoreland on:

  • Native prairies and savannas
  • Lakes, rivers, and wetlands
  • State-listed endangered or threatened species
  • Other high value natural resources important to the community

 3.       Comply with applicable shoreland provisions (Minn. Rules 6120.2500 – 6120.3900) in local zoning ordinances, including:

  • Structure setbacks from the ordinary high water level and bluff lines
  • Impervious surface limits
  • Vegetation cutting and screening requirements
  • Height limits

Other Considerations for Solar Power Structures and Facilities in Shoreland

If a community decides to allow solar power facilities in shoreland as a conditional use, it should take steps to protect shoreland resources when reviewing and approving conditional use permits. While not addressed or required in the shoreland rules, communities should consider amending their ordinances to include specific conditions of permit approval. Following are conditions of approval that communities should consider:

Erosion control under solar panel
  •  The site must have been previously cleared of natural vegetation to serve some other use and be in some other use for a significant period of time – no intensive clearing allowed to site solar facilities. A specific “waiting time” should be determined to avoid vegetation clearance just prior to a solar generation application.
  • Minimize placement of structures and facilities on slopes over 12% in order to reduce potential erosion and runoff from the site.
  • Runoff rate and volume from the site is no greater than if land were covered with 25% impervious surface for a two-year event.
  • All structures and facilities must be screened from view of public waters through siting design, specified limits on structure height, use of ecologically appropriate vegetation for the site, or combination thereof.
  • Native vegetation should be planted on the site to improve habitat conditions for birds, mammals, and pollinators. See the MnDNR Prairie Establishment & Maintenance Technical Guidance for Solar Projects.
  • Use of best management practices for managing erosion control including the establishment of cover crops on prior farmed sites.  Cover crops have proven to stabilize the soil, prevent widespread erosion and runoff, and improve construction conditions at the sites.
  • Only approving sites that have avoided and minimized impacts to valuable wildlife habitat, state-listed endangered or threatened species and that do not have a significant impact to wildlife movement on the landscape.
  • Potential impacts should be coordinated with the appropriate agency to avoid, minimize, or mitigate for unavoidable impacts.  

Communities are encouraged to contact the DNR for help in assessing impacts to these natural resources and in designing facilities that minimize impacts on natural vegetation and wildlife. See the MNDNR Guidance for Commercial Solar Projects.

 Communities can be more restrictive than the statewide minimums and may choose to prohibit solar power facilities in shoreland of all lakes and rivers in their jurisdiction. It is ultimately up to each community to decide which approach to take. Local governments should consult their attorneys/legal staff on the best approach.

If a community elects to amend its shoreland ordinance to more clearly address solar power facilities, all shoreland ordinance amendments must be submitted to the MNDNR for review and approval to ensure substantial compliance with state shoreland rules. Communities are encouraged to engage their area hydrologist as early in the amendment process as possible.

 Solar Projects in River-Related Land Use Regulatory Programs

Solar facilities generating power for off-site use are not allowed in the Lower St. Croix Riverway (Minn. Rule 6105.0370 Subp.2.) and the six Wild and Scenic River districts (Minn. Rule 6105.0100 Subp. 3). Solar facilities located in wild and scenic river districts within city boundaries existing at the time of wild and scenic river designation are managed according to the shoreland rules and should be consistent with the guidance described above for the Shoreland Program.

Editor's Note: This is part 1 of 2. Part 2 will focus on solar power facilities in floodplain areas, and will be in the next issue of Water Talk

Upcoming Trainings

The following trainings by DNR staff are scheduled:

  • July 12, 2017 (W), 1-4 pm - 4-H Building, Murray County Fairgrounds (Slayton); Floodplain Management Basics
  • July 17, 2017 (M), 1-3 pm - Crow Wing County Land Services Building (Brainerd); FAQs to Expect When Getting New DFIRMs, and available Resources 
  • August 2, 2017 (W), 1-4 pm - Wheaton American Legion; Floodplain Management Basics
  • October 5, 2017 (Th), 8:45 am - 4 pm - Thief River Falls; County Selected Special Topics
  • November 2, 2017 (Th), 8:45 am - 4 pm - Blue Earth County Historic Courthouse (Mankato); Special Topics (topics to be chosen by those attending) 

Other trainings are in the process of being scheduled in Fall 2017. MnDNR will be updating the Floodplain Training and Education page as we get upcoming trainings confirmed.

Contact Ceil Strauss at or 651-259-5713 for more details on the topics to be covered at a particular site, or to RSVP for a training.

FEMA "Clear Communication of Risk" Letters

(aka "Section 28 Letters")

Have you - as a local official - received any calls from landowners in your community asking for a copy of their elevation certificate? Have you wondered what precipitated that call? The FEMA "Clear Communication of Risk" Letters could be one explanation. 

Why Letters are Being Sent to Flood Insurance Policy Holders

FEMA’s “Cost of Flood: Policyholders” page gives a good summary explanation:

 "You have received this letter because Section 28, Clear Communication of Risk, within the Homeowner Flood Insurance Affordability Act of 2014* (HFIAA) requires FEMA to clearly communicate true flood risk to individual property owners. To meet this requirement, FEMA is writing to all National Flood Insurance Program (NFIP) policyholders to explain their current policy rating and discuss how and when Elevation Certificates can be useful."

Congress was concerned that many policy holders - especially those with older buildings or that have been "newly mapped" - are not aware:

  1. Their current policy premiums are subsidized (i.e., those structures built before there was a FEMA Flood Insurance Rate Map (FIRM) that use pre-FIRM rates, and those that use the "newly mapped" rates);
  2. They are likely to be at a higher risk of flooding than they realize (especially the pre-FIRM & "newly mapped" structures); 
  3. The pre-FIRM premiums are increasing by up to 18% a year for primary residential properties and 25% a year for non-residential and non-primary residential structures; and
  4. Elevation data may show the structure is not far below (or possibly above) the BFE, and that they would have less expensive premiums if they are rated using the actual elevations.

What Do the Letters Say?

Section 28 Letter E example

There are different letters for each of the main groupings of policy holders:

Letter A - Buildings Newly Mapped Into a High-Risk Flood Area

Letter B - Buildings Standard-Rated, and Outside of the High-Risk Flood Area

Letter C - Buildings Grandfather Rated, And In A High-Risk Flood Area

Letter D - Primary Residential Pre-FIRM Buildings In A High-Risk Area, Paying A Discounted Rate

 Figure 2: Sample FEMA "Clear Communication of Risk" Letter E


Letter A, C, D & E graphic

Letter E - Certain Pre-FIRM Buildings In A High-Risk Area, Paying A Discounted Rate

*Letter F - Buildings Mapped Outside Of A High-Risk Flood Area, And Insured With A Preferred Risk Policy (PRP)

*Letter G - Buildings That Are Post-FIRM, In A High-Risk Flood Area, And Paying A Rate Based On True Flood Risk

* Letters not available on FEMA site as of 6/29/2017.

The "What Will Your Flood Risk Cost?" page (copy to right) is attached to Letters A, C, D and E.

    What Does This Mean For Local Officials?

    • Be aware these letters are being sent to the policy holders in your community, and that it is currently expected those letters will be sent annually.
    • Ask what letter version they received if you get a call that seems to be in response to a Clear Communication of Risk letter. Then you will know what FEMA believes is their category of risk. (Near the bottom of the letter it says, "Additional information is available online for LETTER X . . .).
    • Provide existing elevation data if your community has a FEMA elevation certificate or similar elevation survey data on file.
    • Check other elevation data sources.  If you don't have elevation data for that site, provide available elevation data to help them determine how low (or high) their lowest floor is compared to the Base Flood Elevation (BFE).  For example, check LiDAR elevations (or the 2-foot contours derived from the LiDAR) in your community GIS or public interactive maps, or on the public MnTOPO site.  (Note: To learn more, see "Using MnDNR's MnTOPO Site" article at the bottom of this Water Talk issue.)
    • Direct to FEMA's Letter of Map Amendment (LOMA) process, if applicable. If some cases you will see that the house is actually above the BFE, or that the structure is not actually in the higher risk zone, and they are eligible to apply for a LOMA. See more about the LOMA process at the MnDNR Map Appeals and Amendments site.
    • Direct to information on whether an elevation certificate may help them get better insurance rates either now or in the future: 
    1. Encourage landowners to consult with their agent on whether an elevation certificate may help them get a better rate.
    2. For those receiving a Letter E (for structures built before the first Flood Insurance Rate Maps that have "pre-FIRM" rates), note that their agent can calculate the premiums two ways and use the cheaper of the two: (1) the pre-FIRM rate or (2) rates based on actual elevations. The higher the lowest floor (including basements & crawl spaces) is relative to the BFE, the lower the flood insurance premium will be. If the lowest floor is within a few feet of the BFE, they are more likely to have a lower premium based on the actual elevation rates versus their current "pre-FIRM" rates. Note that the "pre-FIRM rates are increasing up to 18% a year for primary residential and up to 25% a year for non-residential and non-primary residential (i.e., 2nd homes, or rentals), and there is not a cap on those increases, so it is likely that the elevation based rates will be better at some point in the future even if they are not better now. 
    3. Direct them to more information on the relative cost of flood insurance premiums at FEMA's site or on the MnDNR Flood Insurance site.
    4. Caveat: Sometimes it is discovered the policy was not correctly rated and they should have been paying a higher premium.
    • Consider whether to hire a surveyor & get an elevation certificate: Advise landowner to carefully read the letter from FEMA (including the attachments & links), consider input from their agent on whether an elevation certificate could be useful and the available elevation information & BFE for the site, and then determine if it makes sense to pay for an elevation certificate.

    FEMA Map Status Listing

    Actual, scheduled and projected dates since December 2016 Water Talk:

    Preliminary Maps

    • Polk County (revised) - August 2017 (anticipated)
    • Scott County (revised panels) - August 2017 (anticipated)
    • Wright County (revised) - September 2017 (anticipated)
    • Fillmore County (revised) - Q3 2017 (anticipated)
    • Blue Earth County (revised panels) - Q4 2017 (anticipated)

    90-day Appeal Period

    • Carver County - December 29, 2016 to March 29, 2017
    • Fillmore County - February 27 to May 27, 2017

    Letter of Final Determination (LFD)

    • Crow Wing County - February 15, 2017
    • Kittson County - March 29, 2017
    • Marshall County - by end of 2017 (anticipated)
    • Scott County - by end of 2017 (anticipated)
    • Wright County - Q1 2018 (anticipated)
    • Polk County - Q1 2018 (anticipated)

    Effective (6 months after LFD date)

    • Crow Wing County - August 15, 2017
    • Kittson County - September 29, 2017

    Zoning Challenge Answer

    See the Zoning Challenge article earlier in this newsletter for background on the questions.

    Q1. Can we issue a permit, or do we need to wait for new effective maps?

    There are two main considerations:

    Can a permit be issued? - Yes, the local zoning authority can issue a permit at any time. They do not need to wait for preliminary new maps to become effective. (But consider the points in question 3 below).

    What if there are discrepancies in where the floodplain boundary is located when looking at the actual ground elevations versus the mapped Special Flood Hazard Area (SFHA)? - In Minnesota, the community's floodplain management ordinance should have a paragraph (typically titled "Interpretation") that is consistent with Minnesota Rules 6120.5700, subp.3, D: “Where a conflict exists between the floodplain limits illustrated on the official zoning map and actual field conditions, the flood elevations shall be the governing factor in locating the regulatory floodplain limits.”

    So what does that mean? There are two possible scenarios, as highlighted in figure 3 below:

    A.  The actual ground is higher than the base flood elevation (BFE) - Site A below

    1. If the site is within the Special Flood Risk Area on the current effective FEMA map, federal regulations (44 CFR 60.3 (c) (3)) specify the lowest floor must meet minimum elevations. In Minnesota, the minimum elevation is the Regulatory Flood Protection Elevation (RFPE), which is the BFE + 1 foot of freeboard + any stage increase due to establishing the floodway (or any higher local standard).
    2. Note that if the site is really high (e.g., Site A in figure 3 which shows a site about 20 feet above the BFE), it is possible to have a basement and still meet the minimum elevation requirement.
    High site in SFHA & low site outside SFHA
    Figure 3: Comparing actual ground elevations to the Zone A on the Flood Insurance Rate Map (FIRM). Pinkish area is the Zone A. Graphic source: modified MnDNR MnTOPO viewer clip

    B.  The actual ground outside of the SFHA is LOWER than the base flood elevation (BFE) - Example Site B above.

    Since the ground at Site B is lower than the BFE, the community's floodplain ordinance applies and a permit is required to ensure that any new structure meets the ordinance standards.

     Q2. Is the mandatory flood insurance still in effect?

    For current effective Map - YES, since the site IS within the SFHA on the current effective map, and lenders MUST use the current effective map, the lender is obligated to require flood insurance unless a Letter of Map Amendment (or other official map revision) is obtained from FEMA.

    When new map is effective - Once the preliminary new maps become effective the lender would be require to use that new effective map and flood insurance would not be mandatory. (Since the site is near a high flood risk area they should be encouraged to obtain a discounted Preferred Risk Policy.)

    Option to obtain a LOMA - However, the better elevation data could be used to apply for a LOMA. In fact, for a site in Minnesota the two-foot elevation contours show the site is high enough to apply for a LOMA based on LiDAR. See more about applying for a LOMA at MnDNR’s Map Appeals and Amendments page or about a LOMA with LiDAR at MnDNR’s Letter of Map Amendments Using LiDAR Elevation Data page

    Q3. Can we use the base flood elevations (BFEs) on the new preliminary maps?

    When the current effective map has detailed study (i.e., Zone AE) - as in the Zoning Challenge example - the current effective map BFEs continue to be official until the new map's effective date.

    If BFEs are going DOWN the higher BFEs on the current effect map MUST continue to be used for permitting and insurance determinations until the new map is effective.

    If BFEs are going UP the community is encouraged to adopt that preliminary map and say in their ordinance that they will look at both the current effective map AND the preliminary new map, and use whichever is more restrictive. If the community does not adopt the preliminary new maps, they should strongly encourage construction based on the anticipated higher BFE so the structure doesn't become a non-conformity.

    Related previous Water Talk articles:

    Zoning Challenge - Can I Use the New Maps that are Not Effective Yet?

    A Zone Models: When Can They be used for Best Available Data BFEs?

    Using MnDNR's MnTOPO Site

    MnTOPO example

    The image used in the Zoning Challenge question (also shown on the right) is an example of what can be seen at the MnTOPO site. (The labels were added.) 

    1. The MnTOPO viewer is a public site to view two-foot contours derived from LiDAR (and other data) in the State of Minnesota. Use this MnTOPO viewer link, or search for "MnTOPO" (the top result should be "MnTOPO - Elevation Viewer - Minnesota DNR)."

    2. See an article about “MN DNR’s MnTOPO Site” (in the Cool Tools and Sites section) of the March 2014 Water Talk.

    3. The two foot contours in MnTOPO are in the NAVD88 datum, and most older Flood Insurance Rate Maps (FIRMs) are in NGVD29 datum. You must convert one of the elevations to the other datum to compare the elevations. For the county in this example the conversion is 0.0 feet, but the conversion can be as high as 1.4 feet in parts of Minnesota (i.e., in the northwest part of the state).    

    4. To learn more about LiDAR (Light Detection and Ranging), see the short MnDNR Presentation on LiDAR.