6.1.5 Boundary Changes

The District will undertake a boundary assessment to accomplish the following objectives:

  1. Conform the legal boundary more closely to the actual hydrologic boundary.
  2. Work cooperatively with adjacent watershed management organizations to resolve boundary issues including the vicinity of Southdale Shopping Center and portions of the Minneapolis- St. Paul airport.
  3. Evaluate the feasibility of determining and incorporating the groundwatersheds for high-value groundwater resources including Camp Coldwater Spring.

Table 24.  Minnesota Board of Water and Soil Resources recommended wetland management standards.

(Minnesota Routine Assessment Method for Evaluating Wetland Functions, Version 3.0.)

Management Class

Management Strategy

Stormwater Treatment

Buffer1

Mitigation Standard

Hydrologic Guidelines

A—Preserve

Maintain wetland and existing functions, values and wildlife habitat. Possible need for active management of wetland to protect unique features. Apply strict avoidance standards.  May be appropriate to develop a conservation easement.

Avoid conveyed flows where prudent and feasible. Upstream sediment and nutrient pretreatment required to maintain background loading rates. Maintain existing hydrology—divert increased flows. Avoid concentrating flows.

?50 feet for water quality

?100 feet for wildlife habitat.2 Require monuments to mark buffer edge.

WCA minimum or greater replacement ratio with documented replacement of functions/values. Consider requiring buffer replacement.

Bounce (10 yr): Existing

Inundation (1 & 2 yr): Existing

(10 yr): Existing

Runout Control:3 No Change Maintain existing hydrology.

Encourage infiltration and reduced impervious BMPs.

Conduct water budget analysis.

B—Manage 1

Maintain wetland without degrading existing functions, values and wildlife habitat. Apply WCA sequencing process.

Pretreat conveyed flows to maintain background loading rates.

35-50 feet

Require monuments to mark buffer edge.

WCA minimum or greater replacement ratio. Replacement of functions and values on site or in location specified in plan for drain/fill/excavation impacts.

In compliance with Ch. 7050 the entire area affected by storm water or other wastewater flows must be avoided, minimized and replaced at a replacement ratio of 1:1 for all changes in wetland type.

Bounce (10 yr): Existing + 0.5 ft

Inundation (1 & 2 yr): Existing plus 1 day

(10 yr): Existing + 7 days

Runout Control:2 No Change

Maintain existing hydrology.

Encourage infiltration and reduced impervious BMPs.

C—Manage 2

Maintain wetland footprint. Improve wetland biological and plant community diversity/integrity or enhance other functions if possible.  Apply WCA sequencing process. Consider for restoration.

Pretreat all conveyed discharges to remove all heavy particles and maximize removal of fine grained sediment prior to discharging to the wetland

25-35 feet

Require monuments to mark buffer edge.

WCA minimum replacement of acreage and functions/values on site or in location specified in plan for drain/fill/excavation impacts

In compliance with Ch. 7050 the entire area affected by storm water or other wastewater flows must be avoided, minimized and replaced at a replacement ratio of 1:1 for all changes in wetland type.

Bounce (10 yr): Existing + 1.0 ft

Inundation (1& 2 yr): Existing plus 2 days  

(10 yr): Existing + 14 days

Runout Control: 2 0 to 1.0 ft above existing runout

D—Manage 3

Allow for relaxed sequencing and replacement plan flexibility. Consider for restoration/enhancement.

Pretreat all conveyed flows to remove all medium grained and larger sediments.

25 feet

WCA allows mitigation flexibility with minimum standards required in the plan area, see M.R. 8420.0650.

In compliance with Ch. 7050 the entire area affected by storm water or other wastewater flows must be avoided, minimized and replaced at a replacement ratio of 1:1 for all changes in wetland type.

Bounce (10 yr):  No Limit

Inundation (1 & 2 yr):  Existing plus 7 days

(10 yr): Existing + 21 days

Runout Control:2    0 to 4.0 ft above existing runout

Source: Board of Water and Soil Resources.  Recommended Wetland Management Classification System To Accompany the Minnesota Routine  Assessment Method for Evaluating Wetland Functions, Version 3.0

1     Buffers are unmowed, naturalized strips of vegetation around the wetland perimeter.  Buffers would be provided during development or redevelopment

2     Where possible, use 300-foot buffers as per MnRAM (Question #23).

If currently landlocked, new outlet should be above delineated wetland elevation