Projects - Infrastructures
Civil Engineering: Floodplain Modeling & Management

Left Hand Creek
Longmont, Colorado

City of Longmont, Colorado

The mapping of the Lefthand Creek floodplain has not been updated since it was last modeled in 1981. The 100-year floodplain of the creek inundates an extensive area of neighborhoods in southeast Longmont. The effect upon residents within the mapped floodplain includes potential damages due to flooding, as well as the financial impact of mandatory Federal flood insurance premiums and loss of property values.

LORIS has been retained by the City of Longmont to define the floodplain as it exists today and to analyze potential mitigation measures that would reduce the current floodplain impacts. The work is being done in conjunction with another LORIS project involving the design of greenway and trail improvements along the Lefthand Creek corridor throughout southeast Longmont.

LORIS is using the latest in river and floodplain modeling technology (HEC-RAS) to provide the City with an accurate assessment of the floodplain as it currently exists, and of what can be done in the future to mitigate the flood risks. In addition, our familiarity with the rules and requirements of the Federal Emergency Management Agency (FEMA) ensures that study results and recommendations will be compliant with the required Federal standards.