5.9 Summary

The following tables summarize the proposed implementation action items and their relationship to the problems and issues identified in Section 3.0 above, the metrics by which the District will be evaluating progress toward resolving those issues and problems, the estimated District cost of implementing these actions, and anticipated implementation schedule.

Table 14.  Problems and issues identified in the Langdon Lake subwatershed and actions proposed to address them.

 

Problem or Issue

Actions in Implementation Plan

Degree of Improvement

Water Quality

The water quality in Langdon Lake is in the D-F grade range.  Based on this monitoring history, Langdon Lake's water quality is not supportive of swimming.

  • A phosphorus load reduction plan for Langdon Lake that sets forth actions to reduce loading to meet in-lake P concentration goals.  These actions include an enhanced regulatory program, LGU requirements to reduce phosphorus form existing development, and capital projects to reduce internal and external loads.
  • Continue monitoring Langdon. 

Implementation of all the actions in the phosphorus load reduction plan would theoretically reduce in-lake P concentrations, improve water clarity, and meet District water quality goals.

 

Phosphorus loading reductions would be necessary to achieve any of these desired in-lake phosphorus concentrations.  The HHPLS and modeling performed for this plan also noted that internal loading and possibly phosphorus export from wetlands in the subwatershed were likely significant sources of excess phosphorus in the lake

A diagnostic and feasibility study assessing sources of pollutant loading, and capital projects to reduce internal and external load sources.

Would depend on outcome of diagnostic and feasibility of implementing improvements.

 

Runoff from developed areas in the eastern subwatershed receives little if any treatment prior to discharge to receiving waters

Requirements for LGUs to reduce phosphorus load from existing land uses through retrofit or  redevelopment.

Plans completed as LGUs complete their local plans, and implemented as opportunities arise.

No monitoring data are available for Saunders Lake or Black Lake.

Utilize satellite-estimated measure of water clarity to monitor water quality

Would provide a cost-effective means of monitoring these wetlands.

The HHPLS identified several locations where outlets and culverts require maintenance.

LGUs directed to evaluate these locations as part of their local water management planning.

Completed as LGUs complete their local plans.

Water Quantity

Development, redevelopment, and reconstruction in the subwatershed is predicted to increase volume of stormwater runoff from the watershed as well as increased nutrient and TSS loads. 

  • Rules will be amended to require more stringent pollutant load reduction on new development and redevelopment, including adding a volume management requirement.
  • Would depend on ability of developers to incorporate adequate BMPs on their projects and properly maintain them to sustain removal efficiencies.
  • Cooperatively construct regional infiltration improvements to mitigate impact of new runoff from development.
  • Depends on extent of problem and ability to develop cooperative or collaborative improvements.

Future development could increase the volume and velocity of discharges conveyed by the channel from Saunders Lake to Langdon Lake.

  • Rules will be amended to require more stringent pollutant load reduction on new development and redevelopment, including adding a volume management requirement.
  • Would depend on ability of developers to incorporate adequate BMPs on their projects and properly maintain them to sustain removal efficiencies.
  • Cooperatively construct regional infiltration improvements to mitigate impact of new runoff from development.
  • Depends on extent of problem and ability to develop cooperative or collaborative improvements.

The HHPLS identified two locations where the minimum 2 foot freeboard requirement was not met for the 100-year event: the outlet of Saunders Lake and at County Road 110 between Langdon Lake and Lost Lake.

LGUs directed to evaluate these locations as part of their local water management planning.

Completed as LGUs complete their local plans.

Wetlands

The subwatershed includes several Preserve classification wetlands with high to exceptional vegetative diversity, fish and wildlife habitat and aesthetic values that should be protected.

  • Key Conservation Areas identified that include high-value wetlands.  Some of these areas are identified as District priorities for continued implementation of the Land Conservation Program, and thus the District would proactively look for opportunities to conserve these resources. The Capital Improvement Program includes funds for Land Conservation Activities.   In all key areas, LGUs are required to include in their local plans strategies for conserving these values.
  • Ongoing effort that is dependant on property owner willingness to pursue conservation, District budget and staff capacity, and LGU plan completion.

 

  • Rules will be amended to establish management standards based on management classification for impacts to wetlands from development and redevelopment.
  • Implementation of revised rules would help minimize future impacts to the highest-value wetlands while still providing a measure of protection to those that provide mainly downstream resource protection

Wetlands with high to moderate restoration potential in the Regional Park

  • Work cooperatively with Three Rivers Park District to identify potential restorations.
  • Wetlands identified as being of high to moderate wetland potential would be managed according to a Manage 1 wetland classification if they have been assessed as a Manage 2 or 3.   This would minimize further degradation that might make future restoration more difficult or costly.

An initial effort that identifies for restoration those wetlands that would technically be easiest to restore, and those in Key Conservation Areas that may benefit most from restoration.   This would begin to mitigate wetland losses from past development and help to increase the quantity and quality of wetlands present.

Ecological Integrity

  • Areas both in and outside the Park have been designated as Regionally Significant Ecological Areas.  Wetlands with high ecological value are present and those wetlands and associated upland areas should be conserved to preserve their values, create larger areas of ecological value, and connect existing resources.  An ecological corridor through the subwatershed should be conserved to span several subwatersheds.

 

  • Key Conservation Areas identified that include high-value wetlands.  Some of these areas are identified as District priorities for continued implementation of the Land Conservation Program, and thus the District would proactively look for opportunities to conserve these resources. The Capital Improvement Program includes funds for Land Conservation Activities.   In all key areas, LGUs are required to include in their local plans strategies for conserving these values.
  • Ongoing effort that is dependant on property owner willingness to pursue conservation, District budget and staff capacity, and LGU plan completion.

The railroad berm that bisects the subwatershed is a barrier to ecological connectivity.

Work cooperatively with Hennepin County to identify opportunities to improve ecological connectivity

Depends on opportunities and ability to collaborate on improvements.

The Langdon Lake fishery was last surveyed in 1993 and there is no current fish data.

  • Support the fisheries through improvement of water quality, management of aquatic vegetation where internal load management is required, and the promotion of shoreline restoration.
  • Work cooperatively with the DNR to obtain fishery data.

Depends on response of natural system to improved water quality

No detailed information is available on aquatic vegetation in Langdon Lake.

  • Conduct aquatic plant surveys as part of internal load management diagnostic and feasibility studies for Langdon Lake.
  • Completion of this survey would fill this data gap.

Groundwater

There are areas in the subwatershed that are highly sensitive to aquifer impacts.

  • Amend rules to require pretreatment of stormwater discharged to wetlands or infiltration areas in the areas of high aquifer sensitivity.
  • Establish a new District rule that requires an additional level of analysis and review of permitted development and redevelopment where there is a potential for development to adversely impact groundwater connected to a surface water feature.
  • Will help minimize future impacts to groundwater and provide for proactive management rather than reactive

The FAW identified several large recharge wetlands in the subwatershed.  As development occurs it will be important to maintain hydrology to them to preserve groundwater recharge.

  • Amend rules to require infiltration or abstraction of the first one inch of rainfall on new permitted development and redevelopment.
  • Identify a network of surficial aquifer monitoring wells across the watershed, monitor groundwater levels and quality.
  • Promote Better Site Design (Low Impact Development) principles for new development that mimic predevelopment hydrologic regime.

Infiltration on site will assist in preventing further modification of surficial groundwater recharge and help to maintain wetland hydrologic regimes.

Wellhead Protection Areas and associated Drinking Water Sensitivity Management Areas have been identified within this subwatershed. 

 

Stormwater and groundwater management within those areas will be coordinated with wellhead protection plans.

Will help minimize future impacts to drinking water and provide for proactive management rather than reactive

Table 15.  Summary of metrics to be used in evaluating progress toward Langdon Lake subwatershed goals.

Objective

Metric

Existing

Desired

Location

Water Quality

Phosphorus Loading (lbs annually)

610 (Ultimate)

258

Langdon Lake

Water Quantity

Volume Reduction (Acre-feet)

 

45

Watershed-wide

1.5 year discharge (cfs)

4.9

4.9

Watershed-wide

100 year discharge (cfs)

14.0

14.0

Watershed-wide

Ecologic Integrity

Key Conservation Areas conserved (acres)

 

51

Watershed-wide

Wetlands

Wetland Acreage

203.1

203.1 or greater

Watershed-wide

157.5

157.5 or greater

Preserve

11.3

11.3 or greater

Manage 1

12.0

12.0 or greater

Manage 2

8.7

8.7 or greater

Manage 3

Table 16.  Summary of Langdon Lake subwatershed implementation program.

Item

Description

Estimated Cost

Schedule

Section 3.0 Problems Addressed

MCWD Capital Projects

1

Internal load management project

$620,500

2013

3.1.1, 3.1.2, 3.1.5

2

Wet detention pond

$801,700

2013

3.1.1, 3.1.2, 3.1.5

3

Regional infiltration

$18,600

2009

3.1.1, 3.1.2, 3.1.5, 3.2.2, 3.2.3, 3.5.2

$100,800

2012

$83,400

2016

MCWD Data Acquisition/Study

1

Develop infiltration/filtration strategies appropriate to wellhead protection areas and areas of groundwater sensitivity

Part of watershed-wide study

2008

3.1.5, 3.2.1-3.2.4, 3.3.1, 3.4.1, 3.5.1

2

Identify keystone, umbrella, and indicator species, evaluate habitat, and develop conservation strategies

Part of watershed-wide study

2010 and ongoing

3.3.1, 3.4.1, 3.4.2, 2.4.3, 3.4.4

MCWD Land Conservation Program

9

Undertake land conservation efforts in accordance with Figure 19

$602,000

Part of ongoing watershed-wide program

3.3.1, 3.3.2, 3.4.1, 3.4.2

MCWD Regulatory Program

1

Amend District Rules to increase stormwater management requirements for new development

Part of watershed-wide effort

2007-2009

3.1.1, 3.1.2, 3.1.3, 3.1.5

2

Amend District Rules to require abstraction of 1? of rainfall on new development and redevelopment

Part of watershed-wide effort

2007-2009

3.1.1, 3.1.2, 3.1.3, 3.2.2-3.2.4, 3.3.1, 3.5.1 – 3.5.3

3

Amend District Rules to adopt wetland management rules based on wetland management classification

Part of watershed-wide effort

2007-2009

3.3.1, 3.3.2, 3.4.1, 3.5.1, 3.5.2

MCWD Hydrodata Program

13

Monitor Langdon Lake

Part of watershed-wide hydrologic data program

Part of ongoing watershed-wide program

3.1.1, 3.1.2, 3.1.3, 3.1.5, 3.2.2

14

Identify shallow wells to monitor groundwater levels

Part of watershed-wide study

2008 and ongoing

3.2.2, 3.3.1, 3.3.2, 3.4.1, 3.5.1

MCWD Education/Communication Program

1

Provide targeted education materials to key stakeholder groups to meet objectives of plan

Part of watershed-wide education program

Part of ongoing watershed-wide program

3.1.1 – 3.1.3, 3.2.4, 3.2.5, 3.3.1, 3.4.1, 3.5.1, 3.5.2

2

Provide educational opportunities for LGU staff, developers, elected and appointed officials and other interested parties

Part of ongoing watershed-wide education program

Part of ongoing watershed-wide program

3.1.1- 3.1.5, 3.2.2, 3.2.3, 3.3.1, 3.3.2, 3.4.1, 3.5.1, 3.5.2, 3.5.3

3

Develop and distribute model ordinances and design standards that incorporate low impact design principles

Part of watershed-wide education program

Part of ongoing watershed-wide program

3.1.1-3.1.3, 3.1.5, 3.2.2, 3.2.3, 3.4.1, 3.5.1, 3.5.2, 3.5.3

4

Promote the development of a Langdon Lake Association

Part of watershed-wide education program

Part of ongoing watershed-wide program

3.1.1, 3.1.2, 3.1.3, 3.1.5, 3.2.2, 3.3.1, 3.4.1, 3.4.3, 3.4.4

5

Recruit and train volunteers to monitor vegetation in Langdon Lake

Part of watershed-wide education program

Part of ongoing watershed-wide program

3.1.2, 3.1.2, 3.1.5, 3.4.3, 3.4.4

6

Develop a small grant program to provide financial assistance to property owners desiring to implement BMPs on their property or to install demonstration projects on public property

Part of watershed-wide program

2008 and ongoing

3.1.1, 3.1.2, 3.1.3, 3.2.2-3.2.4, 3.3.1, 3.5.1 ? 3.5.3

MCWD Operations and Maintenance

1

Inspect channels and outlet structures every five years

Ongoing activity

Part of ongoing watershed-wide program

3.1.1, 3.1.2, 3.1.3, 3.1.4, 3.1.5, 3.2.1, 3.2.2, 3.2.3

2

Monitor high vegetative-diversity wetlands for exotic species

Part of watershed-wide program

Part of ongoing watershed-wide program

3.3.1, 3.4.1

3

Operate an internal load reduction system

$69,300

annually

Ongoing following construction

3.1.1, 3.1.2, 3.1.5

Collaborative Projects

1

Cooperative project with Hennepin County to identify ways to improve trail corridor connectivity

Part of watershed-wide cost-share program

2008 and ongoing

3.3.1, 3.4.1, 3.4.2

2

Cooperative project with Minnetrista to identify need to stabilize Saunders Lake outlet

Part of watershed-wide cost-share program

2008 and ongoing

3.1.1, 3.1.2, 3.1.4, 3.1.5, 3.2.1, 3.2.2, 3.2.3, 3.2.4

3

Cooperative project with Minnetrista and Three Rivers Park District to identify need to stabilize Black Lake outlet

Part of watershed-wide cost-share program

2008 and ongoing

3.1.1, 3.1.2, 3.1.4, 3.1.5, 3.2.1, 3.2.2, 3.2.3, 3.2.4, 3.3.2