Floodplain Alteration Rule

Download the full Floodplain Alteration Rule (PDF).

Adopted April 24, 2014
Effective June 6, 2014

1. POLICY

It is the policy of the Board of Managers to:

(a) Preserve existing water storage capacity below the 100-year high water elevation of all waterbodies in the watershed to minimize the frequency and severity of high water;

(b) Minimize development below the 100-year high water elevation that will unduly restrict flood flows or aggravate known high water problems.

2. REGULATION

No person shall alter or fill land below the projected 100-year high water elevation of a waterbody without a permit from the District. A Fast Track permit may be issued for 6 inches or less of organic material to be incorporated into existing soil in preparation for sodding or seeding.

3. CRITERIA

(a) Fill shall not cause a net decrease in storage capacity below the projected 100-year high water elevation of a waterbody. The allowable fill area shall be calculated by a professional engineer registered in the State of Minnesota. Creation of floodplain storage capacity to offset fill shall occur before any fill is placed in the floodplain, unless the applicant demonstrates that doing so is impractical and that placement of fill and creation of storage capacity can be achieved concurrently. Any placement of fill prior to creation of floodplain storage capacity will only be allowed upon a demonstration by a registered professional engineer that such work will not aggravate high water conditions.

(b) For fill in a watercourse, in addition to the criteria of paragraph 3(a), the fill shall not cause an increase in the 100-year flood elevation.

(c) The criteria of paragraph 3(a) does not apply to fill in a waterbody other than a watercourse if the applicant shows that the proposed fill, together with the filling of all other properties on the waterbody to the same degree of encroachment as proposed by the applicant, will not cause high water or aggravate flooding on other properties and will not unduly restrict flood flows.

(d) No new impervious surface may be created within the lesser of the 10-year floodplain or 25 feet of the centerline of a watercourse, except impervious area may be created that is:

no larger than 10% of the floodplain area of the parcel(s), or
the surface is an integral component of a linear public roadway or trail.

(e) Ice ridge grading within the floodplain must conform to the original cross-section of the lakebed. Approval for ice ridge grading or removal of ice ridge material from the floodplain requires the applicant to demonstrate that the ice ridge resulted from ice action during the previous winter. No additional material may be placed within the floodplain except in accordance with this Rule.

(f) All new residential, commercial, industrial and institutional structures shall be constructed such that all door and window openings are at a minimum of two feet above the 100-year high water elevation.

4. REQUIRED EXHIBITS

The following exhibits shall accompany the permit application. One set – full size; one set – reduced to maximum size of 11″x17″.

(a) Site plan showing property lines, delineation of the work area, existing elevation contours of the work area, ordinary high water elevation (OHW), and 100-year high water elevation. All elevations must be reduced to NGVD (1929 datum).

(b) Grading plan showing any proposed elevation changes.

(d) Determination by a professional engineer of the 100-year high water elevation before and after the project and the extent of impervious surface within the 10-year floodplain.

(e) Computation by a professional engineer of cut, fill and change in water storage capacity resulting from proposed grading.

(f) Soil boring results if available.

(g) If not otherwise subject to the District Erosion Control Rule, an erosion control plan conforming to sections 5, Erosion Control Plan, and 9, Maintenance, of the Erosion Control Rule.

(h) Any project resulting in greater than 50 cubic yards of fill is required to provide an as-built survey upon project completion which documents the location and volume of both fill and compensatory storage.

5. EXCEPTION

If the 100-year high water elevation of a waterbasin is entirely within a municipality, the waterbasin does not outlet during the 100-year event, and the municipality has adopted a floodplain ordinance prescribing an allowable degree of floodplain encroachment, the ordinance governs the allowable degree of encroachment and no permit is required under this rule.

REVISIONS PURSUANT TO MINNESOTA STATUTES § 103D.341