South Boulder Creek Flood Mapping Study - Home Page

We appreciate your interest in this important study. This Web site contains a wealth of information about the study, technical data, the project team and the opportunities for public involvement. Use the following links to help you navigate through this site:

• Introduction
• Current Study Results
• Status and Next Steps  
• Interactive Flood Maps
• Archives
• Meetings 
• News and Updates
• Frequently Asked Questions (FAQs)
• Public Involvement
• Contact Us

Recent Events:

July 30, 2009 - South Boulder Creek Flood Mitigation Project soliciting proposals for technical consulting services

The City of Boulder and the Urban Drainage and Flood Control District (UDFCD) are currently soliciting proposals from pre-qualified consultants for the South Boulder Creek (SBC) Flood Mitigation Planning Project. The primary focus of the project will be to identify, develop, evaluate and report on flood mitigation alternatives, and conduct a public process to solicit feedback and present options to the public, Water Resources Advisory Board and City Council for review.

The project will evaluate alternatives designed to mitigate the SBC flood hazards that affect structures and areas within city limits.  These areas generally coincide with the "West Valley" area of the SBC floodplain, as depicted in the  mitigation area map.

A risk assessment report was completed in June 2009 in order to support subsequent flood mitigation planning. The purpose of the risk assessment was to identify and quantify life safety, property damage and environmental risks associated with SBC flooding. To assess the risk to life safety, important information includes inundation mapping and basin response time. Property damage assessments involve depth of flooding and the corresponding value of associated losses. Environmental risks consider erosion and sediment transport, the loss of vegetation and changes in the creek path.

Funding has been included in the city's capital improvement program (CIP) in 2009-2011 to complete the flood mitigation planning project. Also, $4.25 million has been included in the city's 2012 budget to help fund the construction of flood mitigation improvements. An agreement with the UDFCD provides a total of $100,000 of supplemental funding for this project.

Background:

In 1996, it was discovered that neighborhoods in east Boulder that were previously considered to be outside the floodplain were actually within the West Valley of the SBC floodplain.  These neighborhoods include about 1,000 structures/homes that are located west of SBC and north of U.S. 36.  This was determined during the University of Colorado's (CU) due diligence investigation into the purchase of the CU-South Campus property. As a result, an updated mapping study was initiated to more accurately identify the flood hazards associated with SBC.

City staff and its consultants recently completed and submitted the updated mapping study results to the Federal Emergency Management Agency (FEMA). The study results are intended to replace the current regulatory mapping that is based on a 1986 United States Army Corps of Engineers (USACE) study. The study was completed with the support and cooperation of FEMA, Colorado Water Conservation Board and Boulder County.  The city is already using the new maps to review, regulate and issue permits for all properties within the South Boulder Creek basin. 

FEMA has completed its review and intends to officially adopt the study in 2010. The process of adopting the mapping study will coincide with the adoption of the Digital Flood Insurance Rate Maps (DFIRMs) for Boulder County. (The new maps will be issued in a digital or electronic format so that they can be accessed over the Internet.) FEMA will not begin using the results of the new maps as it relates to flood insurance requirements until 2010, when the FEMA adoption process is completed.  The adoption process includes the following steps:

• October 2009 - FEMA will issue revised preliminary DFIRMs for Boulder County, beginning a 30-day community comment period.
• November or December 2009 - Notice of intent to adopt the revised flood maps will be published in local newspapers and in the Federal Register, beginning a 90-day appeal period.
• February or March 2010 - End of 90-day appeal period and official adoption of new flood maps is anticipated.

Assuming the study results are officially adopted by FEMA, there will be 700 structures (with a total of approximately 1,200 dwelling units) in the 100-year floodplain (Zone AE).   Currently, there are approximately 460 structures (with approximately 500 total dwelling units) in the 100-year floodplain.  Structures affected by the existing regulatory mapping are also affected under the new study results. Therefore, approximately 240 additional structures (with approximately 700 total dwelling units) will be impacted. The vast majority of these structures are located within existing developed areas of the city within the West Valley area.

June 2009 -  The Updated Risk Assessment Report, June 30, 2009, has been completed in order to support subsequent flood mitigation planning.  

April 2009 - On March 25, 2009, FEMA notified the City of Boulder that it intends to offcially adopt (effective January 2010) the revised floodplain mapping that resulted from the South Boulder Creek flood mapping study. The new floodplain mapping will be used as the basis for the Flood Insurance Rate Map (FIRM) that establishes minimum regulatory floodplain boundaries under the National Flood Insurance Program (NFIP) and federal mandatory flood insurance purchase requirements.

The adoption process for the study results will coincide with the adoption of the related FIRM for Boulder County and will include:

• July 2009 - FEMA will issue revised preliminary digital FIRMs (DFIRMs) for Boulder County, beginning a 30-day community comment period.
• October 2009 - Notices of intent to adopt the revised flood maps will be published in local newspapers and in the Federal Register, beginning a 90-day appeal period.
• January 2010 - End of 90-day appeal period and official adoption of new flood maps is anticipated.

Changes to the Flood Map - April 2009

Letter of Map Amendment (LOMA) Process - April 2009

Flood Insurance - April 2009

Grandfather Provisions for current Flood Insurance Policy Holders - April 2009

•  Grandfathering fact sheed from the National Flood Insurance Program
•  Map and Zone Grandfather Rules from FEMA's National Flood Insurance Program

January 2009 -

Informational memo to City Council regarding mapping study update and plan for new floodplain regulation - Jan. 29, 2009 

December 2008 -

The mapping study will be used to regulate both existing and newly designated floodplain areas and to revise the local Flood Insurance Rate Map (FIRM). Staff began regulating to the designated floodplain areas on Jan. 1, 2008 based on the previous study results. There are few properties that have been added to the 100-year floodplain based on the information submitted to FEMA on Dec. 30, 2008 and staff plans to begin regulating these properties on April 1, 2009. Staff will notify these property owners with a  Notification Letter.

As set forth under National Flood Insurance Program (NFIP) regulations, buildings located in the 100-year floodplain as defined on the FIRM are subject to the mandatory purchase of flood insurance if the property is financed under a federally-backed mortgage. Most home mortgages fall under this category since most lenders are federally regulated. The requirement to purchase flood insurance won't be mandatory until the proposed revision of the FIRM is adopted by FEMA. Adoption of the revised FIRM is expected to occur within the next 12 months and will follow a 90-day appeal period for public review. This provides time for property owners to learn more about the mandatory requirement and to take advantage of coverage and premium options available before the purchase of flood insurance is required.

Owners of properties with buildings previously designated to be in the 100-year floodplain will be sent a  Reminder Letter.

Both letters will inform property owners about these flood insurance requirements, the FIRM and the "grandfather provisions" that provide a mechanism whereby structures previously considered outside the South Boulder Creek floodplain and constructed without flood protection measures may be eligible fore reduced insurance rates.

The study results include:

•  Climatology and Hydrology Report - 2007-05 FEMA Submittal
•  Hydraulic Modeling Report - 2008 FEMA Re-submittal
•  The Updated Risk Assessment Report, June 30, 2009, has been completed in order to support subsequent flood mitigation planning.

It is anticipated that FEMA will complete their review of the revised study results in early 2009. After FEMA completes its review of the mapping study, it will solicit public comment as part of its review process, issuing a notice through the Federal Register.

During the remaining FEMA review period, city staff will continue to regulate to the study results for all annexation and development proposals. 

In addition and pursuant to the city's participation in the National Flood Insurance Program, the city will not remove any property or strucutres from the floodplain until FEMA completes its review. In essence, during the FEMA review period, the city will regulate to the more restrictive flood condition between the existing regulatory map and the proposed study results/maps.

A Risk Assessment was completed in January 2008 in order to support subsequent flood mitigation planning. The risk assessment will be updated with the latest flood study results and flood flood mitigation planning will begin as soon as practical after the flood study results have been accepted by FEMA, Boulder County, the City of Boulder and other agencies. It is anticipated that the focus of these efforts would be primarily to mitigate the impacts of flooding in the west valley, where flood impacts were previously not identified and substantial urban development has occurred.

Currently, funding has been included in the city's CIP in 2008-2010 to complete the risk assessment and the flood mitigation planning effort, and $3 million has been proposed in the city's 2011 budget to help fund flood mitigation improvements. (Specific improvements are yet to be determined by the flood mitigation planning mentioned above.) Also, an agreement with the Urban Drainage and Flood Control District has been secured and provides a total of $100,000 of supplemental funding for flood mitigation planning. 

Background

The South Boulder Creek (SBC) Flood Mapping Study was initiated to more accurately identify the floodplain and assess the flood hazard in east Boulder. It will determine the intensity and volume of rainfall and flooding that could be anticipated during several different storm events and define the extent and depth of the resulting flooding for each. It will reconcile the information from previous studies and use a more technologically advanced approach than used in the earlier studies.

The SBC mapping study results are intended to replace the current regulatory mapping that is based on a 1986 United States Army Corps of Engineers (USACE) study. The study was completed with the support and cooperation of the Federal Emergency Management Agency (FEMA), Colorado Water Conservation Board (CWCB) and Boulder County.

On April 17, 2007, City Council authorized the submittal of the SBC Flood Mapping Study results to the FEMA, and the mapping study was submitted on Aug. 23, 2007. City staff received comments on the initial submittal and addressed these comments in a re-submittal package dated Dec. 30, 2008 -  FEMA Re-submittal Letter

Last Updated on Monday, 05 October 2009 12:22