Boulder County has one of the most significant post-disaster flood zone histories in Colorado. The September 2013 Front Range floods killed 10 people in Boulder County, destroyed hundreds of homes, and caused FEMA to substantially revise its Flood Insurance Rate Maps for the county. Properties along Boulder Creek, Left Hand Creek, St. Vrain Creek, and numerous canyon streams now face updated flood zone designations that reflect the 2013 event. In 2026, elevation certificates in Boulder and Longmont run $500 to $900.
The 2013 Boulder Floods and FEMA Map Changes
Over September 9 to 15, 2013, a slow-moving storm system dropped more than 12 inches of rain across the Boulder County mountains, triggering flooding across the entire county. Boulder Creek flooded through downtown Boulder, damaging buildings along the creek corridor and the University of Colorado campus area. Left Hand Creek flooded catastrophically through Jamestown, destroying much of the mountain town. St. Vrain Creek in Lyons and Longmont flooded severely, destroying bridges, roads, and structures throughout both communities.
FEMA conducted an extensive flood mapping update for Boulder County after 2013. The revisions expanded flood zone designations in many areas that had been underestimated on the previous maps. If you have a property in Boulder County that received an elevation certificate before September 2013, the current FEMA flood zone status of that property may have changed, and the prior certificate may be based on an outdated flood map.
Primary Flood Zones in Boulder County
- Boulder Creek: Runs east through Boulder; the creek corridor through downtown, the university area, and east Boulder has Zone AE designations. The 2013 event affected properties along the full length of Boulder Creek within city limits.
- St. Vrain Creek: Runs through Lyons and Longmont; Lyons, at the confluence of the North and South St. Vrain Creeks, is one of the most flood-prone communities in the county. Longmont’s St. Vrain corridor also has significant flood zone coverage.
- Left Hand Creek: Runs from Jamestown through the Lefthand Canyon area; Jamestown and properties along Left Hand Creek below it are in active flood zones.
- South Boulder Creek: Runs through south Boulder and Louisville; some flood zone coverage in the corridor.
Cost and Process
Urban Boulder and Longmont elevation certificates run $500 to $900. Canyon and mountain properties (Lyons canyon, Jamestown, Nederland) run $600 to $1,000 due to terrain access time. The field visit takes 1 to 2 hours for accessible properties; the completed certificate is delivered in 1 to 3 weeks.
Only a licensed Professional Land Surveyor can complete a FEMA-accepted elevation certificate. To find an elevation certificate surveyor in Boulder County, browse our directory. Every surveyor listed is sourced from Colorado state licensing records.