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Home My WebLink About09 26 2016 Flood Reduction Study PresentationSurface Water Modeling & Flood Damage Reduction Study Policymakers Joint Workshop September 26, 2016 Welcome 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP2 Introductions & Purpose 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP3 The goal of the meeting is to have the 13 policymakers weigh in on the recommendations of their staff on how to proceed in the short and long term Study Results 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP4 Updated Flood Model •PCSWMM computer model •Atlas 14 precipitation data, land use/land cover, soils, topography, imperviousness, routing, storage •Calibrated to 2014 •Future internal use Study Results 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP5 Updated Flood Model •Atlas 14 Data •Average record length 50 years (vs. TP-40) •Many more stations now included •Accepted resource for local, state, and federal agencies 9/26/2016 Surface Water Modeling and Flood Damage Reduction Study | 2ND JOINT WORKSHOP6 Prior Lake elevation extremes chart goes here 9/26/2016 Surface Water Modeling and Flood Damage Reduction Study | 2ND JOINT WORKSHOP7 Study Results 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP8 Stormwater Management •Existing conditions •Future conditions –development Study Results 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP9 Study Results 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP10 9/26/2016 Surface Water Modeling and Flood Damage Reduction Study | 2ND JOINT WORKSHOP11 9/26/2016 Surface Water Modeling and Flood Damage Reduction Study | 2ND JOINT WORKSHOP12 Matrix Results: Review of Options 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP13 Actively Manage Prior Lake Outlet (Option G) MATRIX RANK:#1 ESTIMATED COST:$0.1M BENEFITS: •Quickly implemented •Reduces flooding 3” •Minimal negative effects •Relatively inexpensive CHALLENGES: •Needs DNR approval •Less flood reduction benefits than other options •Potential to cause detrimental effects downstream Matrix Results: Review of Options 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP14 Upper Watershed Storage (Option D) MATRIX RANK:#2 ESTIMATED COST:$3.9M BENEFITS: •Can be completed incrementally •Reduces flooding 15” •Water quality benefits •Reduces flooding on Spring Lake CHALLENGES: •Negotiate agreements with upstream landowners •Potential negative lake effects during droughts •Long time to implement •Permitting required Matrix Results: Review of Options 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP15 Prior Lake Outlet Modification (Option C) MATRIX RANK:#3 ESTIMATED COST:$2.8M BENEFITS: •Reduces flooding by 10” •Some rights already secured •Implementation timeline 10-15 years CHALLENGES: •Will be difficult to secure permits and approvals •Potential negative lake effects during droughts •Need to address impacts to downstream resources Matrix Results: Review of Options 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP16 Combine Options B, C & D (Option E) MATRIX RANK:#4 ESTIMATED COST:$10.8M BENEFITS: •Provides the most flood reduction benefits -reduces flooding 34” •Water quality benefits •Reduces flooding on Spring Lake CHALLENGES: •Combines challenges of included options •Longest timeline •Expensive option Matrix Results: Review of Options 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP17 Enhanced Protection (Option A) MATRIX RANK:#5 ESTIMATED COST:$1M BENEFITS: •Quick to implement •Relatively low cost •No permits or approvals are required CHALLENGES: •No flood level reductions •No water quality benefits •Requires effort by landowners and City staff Matrix Results: Review of Options 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP18 Spring Lake Storage (Option B) MATRIX RANK:#6 ESTIMATED COST:$4.1M BENEFITS: •Reduces flooding by 9” •Some water quality and natural resource benefits CHALLENGES: •Increases lake levels on Spring Lake during flood events •Requires multiple permits and approvals •Needs agreement from all Spring Lake landowners Matrix Results: Review of Options 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP19 Floodproofing/Buyouts (Option F) MATRIX RANK:#7 ESTIMATED COST:$35M BENEFITS: •Protects or removes primary structures below the 100-year flood level CHALLENGES: •Most expensive option •Requires permits to install floodproofing measures •Does not reduce peak flood levels on Prior Lake or address inaccessibility to properties Photo courtesy: FEMA/Calvin Tolleson Reaffirm Goals 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP20 Goals from the 2/8/16 Policymakers Meeting 1.Protect public safety and maintain emergency access 2.Protect public utility infrastructure 3.Maintain traffic flow through the County Road 21 corridor 4.Maintain access to private properties Staff Recommendation 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP21 Short-term Goal •Option A –Enhanced Protection. An interim strategy to address any flooding event while other permanent options are being developed. •Option G –Actively Managed Prior Lake Outlet. A strategy that involves more deliberate operation of the existing low-flow gate. Staff Recommendation 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP22 Long-term Goal •Upper watershed storage is the most feasible option considering all factors in the decision matrix •Lake Level reductions can be incrementally achieved •Provides the most secondary benefits Staff Recommendation 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP23 Level of Protection •High priority to reduce the flood level on Prior Lake to 905.5 at the 25 year return period •Secondary priority to cost effectively provide additional flood damage reduction based on future assessments as part of adaptive management strategy 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP24 Staff Recommendation 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP25 Level of Protection •High priority to reduce the flood level on Prior Lake to 905.5 at the 25 year return period •Secondary priority to cost effectively provide additional flood damage reduction based on future assessments as part of adaptive management strategy Adaptive Management 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP26 Assess Problem Engineer & Design Complete Project Learn & Evaluate Adjust Plans Adaptive management is a systematic approach for improving overall results by learning from incremental outcomes Adaptive Management •Regular assessment every 5 years •Explore alternative ways to meet objectives •Adjust management actions as necessary 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP27 Potential Funding Options 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP28 USDA -Farm Service Agency •Conservation Reserve Program (CRP) Natural Resources Conservation Service (NRCS): •Environmental Quality Incentives Program (EQIP) •Agricultural Conservation Easement Program (ACEP) MN Board of Water & Soil Resources (BWSR): •Reinvest in Minnesota (RIM) Wetlands and Grassland Reserve Program •Clean Water Fund (CWF) Grants •Erosion Control and Water Management Program MN Department of Natural Resources (MnDNR): •Conservation Partners Legacy (CPL) Grants •Flood Hazard Mitigation Grants •Wetland Tax Exemption Program MN Pollution Control Agency (MPCA): •Section 319 Grants •Clean Water Revolving Fund US Army Corps of Engineers: •Flood Risk Management Program •Flood Plain Management Services & Planning Asst. (studies) •Continuing Authorities Program (CAP) •Minnesota Silver Jackets Program •Hazard Mitigation Grant Program •Pre-Disaster Mitigation Program CURRENT GRANTS AVAILABLE Potential Funding Options 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP29 OTHER POTENTIAL FUNDING SOURCES: •Legislative Cost Share •Water Management (Special Benefit) District •Special Assessment •Stormwater Utility •Watershed District Levy •Private Grants Policymakers Discussion 9/26/2016 Surface Water Modeling & Flood Damage Reduction Study | SECOND JOINT WORKSHOP30 Given the goals affirmed earlier tonight and the study results, how do the recommendations of your staff reflect your perspective for moving ahead in a coordinated manner? Surface Water Modeling & Flood Damage Reduction Study Policymakers Joint Workshop September 26, 2016