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State of AlaskaSOA / CommerceDCCED / Community & Regional AffairsDCRA / Planning & Land Management / Risk MAP / Matanuska-Susitna Borough Risk MAP Study

Alaska Risk MAP Program

Community Risk MAP Studies: Matanuska-Susitna Borough

FEMA and the State of Alaska are conducting a Risk MAP Study in the Matanuska-Susitna Borough that began in March 2013 and was completed in September 2019.

Risk MAP Discovery Documents

Discovery is the first part of the Risk MAP process. During this initial phase, the State, FEMA and local entities work together to collect data regarding local flood and other hazard risks. FEMA has data on national and regional levels, however FEMA relies heavily on information and data provided by communities because local officials are able to provide a holistic view of their communities and their known risks. The State prioritizes a watershed for Discovery based on evaluations of risk, need, availability of elevation data, regional knowledge of issues, and local input. After this data is collected, the study is evaluated on an extensive list of criteria.

Risk MAP Study Scope Documents

If it is determined during Discovery that a Risk MAP project is appropriate for the community and the project involves flood engineering analysis, the project team will conduct additional coordination with the impacted communities to discuss anticipated changes to the Flood Insurance Rate Map (FIRM) and Flood Insurance Study (FIS).

Prior to work starting on any risk assessment or flood insurance study mapping, a meeting must be held with the community to share the scope of work and explain the deliverables resulting from the project. In addition to sharing the Scope of Work at this meeting, FEMA provides a Partnership Agreement to the community, a non-binding document that outlines roles and responsibilities during the Risk MAP study.

Draft Workmaps - Released August 28, 2015

Draft Workmaps are an interim or “draft” product that FEMA shares with communities in advance of the release of the Preliminary Flood Insurance Rate Maps (FIRMs) to get early input on the mapping and underlying data.

Following the release of the Draft Workmaps, FEMA and the State will schedule a Flood Risk Review (FRR) Meeting with the local jurisdiction (See next drop-down).

To locate and open a draft workmap using a map of the Matanuska-Susitna Borough, click here.

Flood Risk Review Meeting

Following the release of Draft Workmaps, FEMA and the State will hold a Flood Risk Review (FRR) Meeting with the local jurisdiction. The FRR Meeting provides local officials with an opportunity to review and ask questions about the flood study and its results. The meeting allows the project team to highlight the flood risk associated with the study so that local officials can begin communicating that risk to impacted residents and businesses. The FRR Meeting also gives local officials the opportunity to comment on areas where they believe risks are inappropriately mapped (understated or overstated). By identifying concerns early in the map development process, FEMA can avoid delays and costly revisions to the preliminary FIRMs following their release.

Preliminary Flood Insurance Rate Maps (FIRMs) - Released August 19, 2016

To locate and open a Preliminary Map Panel using a reference map of the Matanuska-Susitna Borough, click one of the map thumbnails below:

Reference Map 1: Cities of Houston, Wasilla and Palmer

Click to find and open a Preliminary Map Panel

Reference Map 2: Talkeetna River to Willow Creek and Nancy Creek State Recreation Areas

Click to find and open a Preliminary Map Panel

Preliminary Flood Insurance Study and FIRM Database - Released August 16, 2016
Consultation Coordination Officer (CCO) Meeting

After the release of preliminary FIRMs and FIS reports, FEMA holds meetings to present them first to community officials at a Consultation Coordination Officer (CCO) Meeting. Any changes in flood risk will be explained and participants will have an opportunity to provide feedback on the products. This is also the meeting where public outreach needs are discussed.

The CCO Meeting is required by 44 CFR 66.5 (f): (f) The community shall be informed in writing of any intended modification to the community's final flood elevation determinations or the development of new elevations in additional areas of the community as a result of a new study or restudy. Such information to the community will include the data set forth in paragraph (e) of this section. At the discretion of the Regional Administrator in each FEMA Regional Office, a meeting may be held to accomplish this requirement.

Resilience Documents and Workshop

Resilience is the final phase of the Risk MAP process when stakeholders of the Risk MAP process reflect on how the new information, tools and products of the Risk MAP study can be used to increase resilience in the community. A Resilience Workshop is an in-person meeting led by FEMA, the State Risk MAP Coordinator and the Risk MAP Project Team. The goal of the meeting is to help communities understand the results of the risk assessment products and to develop resilience-focused strategies using the new data and resources. During this meeting FEMA, State and Local officials engage with the mapping partners to identify the hazard risks through the use of the Risk MAP Products Suite, providing a new perspective and understanding of flood risk within their community.

Region X Service Center Quarterly Reports

During the course of a flood study, FEMA's mapping contractor will provide Detailed Status Updates which are emailed quarterly to the community and project team. These updates include the overall project status, changes to the scope or schedule of the project, and a detailed overview of the individual technical tasks associated with the project.

Study Scope

The scope of work of the Matanuska-Susitna Borough Risk MAP Study includes (see also the map below):

Detailed hydrology and hydraulic modeling to include 71.9 miles of riverine study, perform approximate riverine analysis for 316.6 miles, and delineate 15.4 miles of existing areas. Floodplain boundaries will be updated for the 1-percent and 0.2-percent-annual-chance (100- and 500-year) flood events. The rivers to be updated include:

  • Updated detailed modeling (Zone AE) will be completed for:
    • Little Susitna River (including Split Flows 1-3) = 39.2 mile
    • Willow Creek = 13.3 miles
    • Willow Creek Tributary = 7.1 miles
  • Limited detail modeling (Zone A with structures) will be completed for:
    • Wasilla Creek = 10.7 miles
  • Updated Approximate Studies (Zone A) will be completed for:
    • Upper Matanuska River = 14 miles
    • Point MacKenzie = 2 miles – roughly from Walsop Road to 2 miles downstream of Walsop Road
    • Various Zone A = 289.9 miles
  • Redelineation of Effective Detailed Studies (Zone AE) will be completed for:
    • Deception Creek and Tributaries 1-3 = 15.4 miles

US Army Corps of Engineers (USACE) Studies (Leverage - Zone AE) will also be incorporated to include:

  • Matanuska River = 3.9 miles
  • Knik River = 2.7 miles
  • Bodenburg Creek = 5.7 miles

Regulatory Products

  • Preparation of a regulatory Flood Insurance Study (FIS) Report document to the Community. A FIS is a book that contains information regarding flooding in a community and is developed in conjunction with the FIRM. The FIS, also known as a flood elevation study, frequently contains a narrative of the flood history of a community and discusses the engineering methods used to develop the FIRM. The study also contains flood profiles for studied flooding sources and can be used to determine Base Flood Elevations for some areas.
  • Preparation of a regulatory Flood Insurance Rate Map (FIRM) map for all panels within the Community which identifies the Community's flood zones, base flood elevations, and floodplain boundaries. This map is used to determine where the purchase of flood insurance is required for properties with federally-backed mortgages. The preliminary FIS and DFIRM’s are scheduled to be released in September 2015.
  • Collect LiDAR in Summer 2015. This data will be delivered to the community by Fall 2015.
  • All of the above datasets will be in the in the North American Vertical Datum of 1988.
  • The State and FEMA will provide guidance, feedback, coordination and technical support throughout the Risk MAP Project Life Cycle.

Non-Regulatory Products and Technical Assistance

  • A Changes Since Last FIRM map and dataset will be prepared that identifies areas where the Special Flood Hazard Area, floodway, and/or flood zone designations have changed since the previous flood study. Engineering factors that may have contributed to the changes such as data used and level of study performed will also be identified. Estimates of structures affected by the changes will be quantified and summarized to capture increases/decreases in known risk areas and enable local officials to better plan for outreach needs.
  • 10%, 4%, 2%, 1%, and 0.2% annual-chance depth grids will be developed for detailed analysis and 1% annual chance depth grids for approximate riverine analysis. Depth grids depict the depth of flooding at locations throughout a community and when combined with other information, such as first floor elevations, are invaluable in understanding risk.
  • A non-regulatory Risk Report will be prepared which include narratives on multiple hazards and risk exposure, and explains the risk assessment methodology and results for each community. The risk report will provide loss estimations using Hazus for flood, earthquake, landslide, and wildfire hazards. Flood depth grids and USGS ShakeMaps will be incorporated into the Hazus analysis. Local data will be added to Hazus for more accurate results. Other natural hazards will include a summary and an exposure analysis.
  • A Flood Risk Database will be developed which houses data collected, created, and analyzed during the project. This data can be used by the Community to recreate maps, develop reports and other products, and to perform additional analysis.
  • Areas will be highlighted where risk reduction actions may produce the highest return on investment.
  • The Borough will be provided with technical assistance for HAZUS projects.
  • The Borough will be provided with Areas of Mitigation Interest findings and recommendations based on best available data.
  • The State and FEMA will provide guidance, feedback, coordination and technical support throughout the Risk MAP Project Life Cycle.

Project Status

The FIRMs and FIS became effective on September 27, 2019, six months after the Letter of Final Determination was issued to the Borough. Community officials were sent the Revalidation Letter that lists previously issued Letters of Map Change (LOMC) that have been reaffirmed for the new FIRM. The Revalidation Letter became effective one day after the publication of the community’s revised final FIRM. The Revalidation Letter does not list LOMCs that have been incorporated into the revised panel,LOMCs that are superseded by new or revised mapping, or LOMCs that are no longer valid. While the Summary of Map Actions (SOMA) is a preliminary assessment of which LOMCs may still be valid after the new maps are issued, the Revalidation Letter is the final, effective determination of the LOMCs which remain valid. The SOMA and the Revalidation Letter are meant to assist community officials in the maintenance of the community’s FIRM.

The following table illustrates project status and includes major milestones with dates:

Activity Actual or Projected End Date
Discovery Interview March 11, 2013
Discovery Meeting April 23, 2013
Flood Study Kick-Off Meeting December 13, 2013
Draft Work Maps Issued August 28, 2015
Flood Risk Review Meeting January 20, 2016
Preliminary DFIRM/FIS Release August 19, 2016
Consultation Coordination Officers (CCO) Meeting January 4, 2017
Draft Multi-Hazard Risk Report January 10, 2017
Public Meeting/Workshop March 15-16, 2017
90-Day Appeal Period Starts October 27, 2017
90-Day Appeal Period Ends January 25, 2018
Revised Preliminary DFIRM/FIS Release August 24, 2018
Letter of Final Determination March 27, 2019
Risk MAP Resilience Workshop To Be Determined*
Delivery of Final Risk Report and Risk Assessment Database September 2019
Maps and FIS become Effective September 27, 2019

*All projected dates are subject to revision as the project progresses

Map of Matanuska-Susitna Borough Study Scope

Matanuska-Susitna Scope Map
Click on image to open larger map

Matanuska-Susitna Borough Discovery
(FEMA Region X Workspace)
FEMA Region X Risk MAP Newsletters

For more information contact:

Rebecca Rein

State of Alaska Risk MAP Coordinator
Division of Community and Regional Affairs
Department of Commerce, Community, and Economic Development
550 West 7th Avenue, Suite 1650, Anchorage, AK 99501-3569
Phone (907) 269-3037
Fax (907) 269-4539
Email: rebecca.rein@alaska.gov

Revised 12/02/2024

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