Floodplain Management

Floodplain Maps – Know Your Risk

Everyone has flood risks. Know Yours!
Boulder County has 21 drainages with mapped floodplains. Floodplain maps identify areas at risk of inundation during the 1-percent-annual-chance (100-year) flood, also known as the regulatory floodplain. However, a property can still be at risk of flooding if it is mapped outside a regulatory floodplain.
Boulder County’s regulatory Floodplain Overlay Zoning District is comprised of both the FEMA and Boulder County floodplain maps.

Floodplain Maps

• The county’s interactive Official Regulatory Floodplain Map shows both the FEMA and Boulder County floodplains.
• The FEMA floodplain can also be viewed on the FEMA Map Service Center.
• The Boulder County Assessor’s property search site includes flood risk by address.

Flood Zone Determinations

For an official determination of the flood zones on your property (unincorporated areas only) or to ask questions about the floodplain maps in your area, contact the Floodplain Administration team at 303-441-3930 or email floodplainadmin@bouldercounty.gov.

Elevation Certificates on file with the county are available upon request.

For information on floodplains in incorporated towns and cities, contact the appropriate municipality.

Upates to Floodplain Maps

The county supports and participates in periodic updates to floodplain maps with neighboring communities and FEMA. These updates ensure that the floodplain maps reflect current conditions.

Individual homeowners may apply to the Federal Emergency Management Agency (FEMA) for a Letter of Map Amendment (LOMA) if they believe their property has been inadvertently mapped within the 100-year floodplain.

Colorado Hazard Mapping Program

Following the 2013 flood, the state legislature allocated funds to the Colorado Water Conservation Board (CWCB) to conduct natural hazard mapping. The Colorado Hazard Mapping Program (CHAMP) updated the previous floodplain maps and created new floodplain maps where none existed for waterways most affected by the 2013 flood.

For more information, visit the Floodplain Remapping Project website.

Flood Insurance

Boulder County participates in the National Flood Insurance Program (NFIP), which is administered by the Federal Emergency Management Agency (FEMA). The NFIP makes federally-backed flood insurance available for all buildings, whether they are in the floodplain or not. Flood insurance covers direct losses caused by surface flooding, including a river flowing over its banks, a lake or ocean storm, and local drainage problems. Communities that participate in the NFIP must adopt and enforce floodplain management regulations.

The NFIP insures buildings, including mobile homes, with two types of coverage: structural, and contents. Structural coverage is for the walls, floors, insulation, furnace, and other items permanently attached to the structure. Contents coverage may be purchased separately provided the contents are in an insurable building.

What you should know:

• Boulder County’s participation in the NFIP’s Community Rating System (CRS) results in a 25% reduction in flood insurance premiums purchased through the NFIP for property in unincorporated Boulder County
• General homeowners insurance does NOT cover floods
• Flood insurance is available to all homeowners, renters, and business owners in unincorporated Boulder County
• There is a 30-day waiting period when purchasing flood insurance
• Flood insurance is backed by the federal government, but can be purchased through a local agent
• Contact your insurance agent today to ask about flood insurance!

Visit FEMA’s Flood Smart website for more information on why you might consider purchasing flood insurance and where to find an agent in Boulder County who can help.

The Mandatory Purchase Requirement:

Owners of property within the FEMA 100-year floodplain who hold a federally-regulated mortgage are required by law to have flood insurance. Even if not federally required, a lender can require flood insurance regardless of flood zone.

Development Requirements – Build Responsibly

Before beginning any construction (new development, addition, remodel, repair, filling, grading, etc.) in the regulatory floodplain, contact the Floodplain Administration team at 303-441-3930 or email floodplainadmin@bouldercounty.gov for specific requirements. A Floodplain Development Permit is required for all floodplain development.

Requirements for floodplain development can be found in the following regulations:

• Land Use Code – Article 4-400
• Boulder County Storm Drainage Criteria Manual

Stay Informed During a Flood

Visit bocoalert.org to sign up for county emergency alerts.

Learn more about disaster preparedness and the county’s Multi-Hazard Mitigation Plan.

The Mile High Flood District maintains real-time storm and flood data.

Drainage & Flood Control

The Floodplain Administration team collaborates with other departments and agencies on stream restoration, mitigation, and flood control projects that focus on accommodating floods instead of controlling them.

Storm Water Drainage

he county is a member of the Keep It Clean Partnership (KICP), which is dedicated to protecting water quality and reducing storm water pollution.
KICP has developed programs to meet requirements established by the EPA regarding storm water regulations. These regulations require communities to help maintain water quality and stream health. Maintaining clean water is critical to both our health and the health of the ecosystem.

Flood Control

The county is partially located within the Mile High Flood District (MHFD), which was created to assist local governments with drainage and flood control problems.
The MHFD assists the county with flood warning forecasts, flood studies, and design, construction, and maintenance of urban drainage infrastructure.

Natural Floodplain Functions

With over 98,000 acres of open space, the county is committed to conserving natural, cultural, and agricultural resources. While open space provides opportunities for recreation, education, and agriculture, it also serves an important function of maintaining an undeveloped floodplain to allow natural flooding to occur while minimizing damage to homes and infrastructure.

Community Rating System

The National Flood Insurance Program’s (NFIP) Community Rating System (CRS) was implemented in 1990 to recognize and encourage community floodplain management activities that exceed minimum NFIP standards. Under the CRS, flood insurance premiums of the county’s residents and businesses are discounted to reflect the county’s work to:

1. Reduce flood damage to existing buildings,
2. Manage development in areas not mapped by the NFIP,
3. Protect new buildings beyond the minimum NFIP protection level,
4. Preserve and/or restore natural functions of floodplains,
5. Help insurance agents obtain flood data, and
6. Help people obtain flood insurance.

Boulder County currently has a CRS rating of 5. As a result, all NFIP policies in unincorporated areas receive a 25% premium discount, regardless of flood zone. Rate reductions are applied automatically when policies are purchased or renewed.