Fluvial Hazard Zones

CWCB is committed to assisting communities that wish to map and acknowledge FHZs through the following actions:

• Providing technical and regulatory advisory assistance to communities that wish to map and manage FHZs.
• Allowing FHZ mapping and programs to be considered for competitively awarded grant funding with a 1:1 match requirement via the Colorado Watershed Restoration Grant Program.
• Providing resources to and partnering with organizations and local agencies that are implementing Stream Corridor Easements.

FHZ mapping using a version of the CWCB Protocol has been done on approximately 500 miles of streams for the FHZ Pilot Program as well as for local organizations, governments, and districts. This FHZ mapping is across a broad spectrum of stream types and covers all the different types of FHZ mapping protocols. Draft FHZ maps have been produced for the following streams and communities: East Plum Creek (Castle Rock), Sand Creek Upper (Aurora), Sand Creek Urban (Denver, Commerce City). Rooney Gulch (MHFD, Morrison), Left Hand Creek (Boulder County), St. Vrain Creek (Boulder County), South Boulder Creek (Boulder County), Middle Boulder Creek (Nederland), South Beaver Creek (Nederland), Fall River (Estes Park), Fish Creek (Estes Park), Upper Big Thompson (Estes Park), Black Canyon Creek (Estes Park), San Miguel River (San Miguel County), South Fork San Miguel River (San Miguel County), Eagle River (Eagle County), Saguache Creek (Saguache County), Fall Creek (San Miguel County), Gunnison River (Delta), Uncompahgre River (Delta), Indian Creek (Huerfano County), Middle Creek (Huerfano County).

Numerous benefits can come from mapping and incorporating FHZ maps into your communities planning. These include but are not limited to:

Avoiding Flood Damages Through Planning And Informed Development

Ultimately the most cost-effective tool to mitigate the impact of fluvial hazards is to reduce exposure to the hazard though forward-looking land use planning and/or regulations and standards for development within mapped fluvial hazard zones. The FHZ delineation process and the resulting maps are intended to provide local land use, floodplain, and emergency response managers insight into the likely long-term behavior of their streams and serve as additional hazard information. It also communicates these hazards to the public so that they are better informed in making emergency preparations as well as personal and business decisions.

Wildfire Planning And Response

FHZ maps are a valuable tool for communicating hazards associated with rainfall after wildfires. After a wildfire, FHZ maps can be quickly and cost-effectively created to delineate areas vulnerable to sediment and debris impacts spurred by rainfall over the burn scar. Mapping these post-fire hazards may allow downstream residents to prepare by preemptively moving vehicles, storage units, and other items to safer locations and to develop evacuation plans. Furthermore, conserved and natural stream corridors, especially those where beaver have been reintroduced and wet meadows and ponds are present, are thought to provide natural fire breaks, potentially aiding a community’s firefighting effort during a wildfire.

Identification Of Wildlife, Open Space, And Recreational Opportunities

Fluvial geomorphic processes create shifting mosaics of highly productive habitat for riparian, aquatic and terrestrial species. These corridors provide diverse, dynamic, and complex habitats that are among the most important to protecting biodiversity in Colorado. They also provide opportunities to protect (and improve) water quality. This diversity of habitat creates recreational opportunities for wildlife viewing, fishing, foraging, and hunting, as well as trail and path networks for recreation and alternative transportation. Using FHZ maps, conservation and recreation organizations may identify lands where the environmental benefits of unconstrained rivers are enhanced by the societal benefit of limiting human exposure to fluvial geomorphic hazards.

Conservation Of Agricultural Lands And Practices

Many lands adjacent to streams are currently being used for agriculture and grazing. Generally speaking, these land uses are considered compatible for areas within the FHZ. Mapping the FHZ and incorporating the boundaries into community plans can help to prioritize the maintenance of existing agricultural land uses and practices in stream corridors.

Some of the challenges associated with fluvial hazard zone mapping include:

• Political will and community support is required to implement limitations on development location, however there are a multitude of ways in which these maps can be used for planning that do not involve regulation.
• Typically requires high-definition topographic data of the stream corridor (e.g., LiDAR).