FLOOD10545 ‎(2)‎

• County: Adams
• County: Jefferson
• Community: Arvada
• Stream Name: Ralston Creek
• Title: LOMR - Affected Panel 0006 B - Case No. 97-08-414P
• Date: 8/12/1998
• Prepared For: Arvada
• Prepared By: FEMA
• Floodplain - Doc Type: Historic FEMA Regulatory Floodplain Information

CHANGES ARE MADE IN DETERMINATIONS OF BASE FLOOD ELEVATIONS FOR THE CITY
OF ARVADA, JEFFERSON AND ADAMS COUNTIES, COLORADO, UNDER THE NATIONAL
FLOOD INSURANCE PROGRAM

On February 19, 1992, the Federal Emergency Management Agency identified Special Flood Hazard Areas
(SFHAs) in the City of Arvada, Jefferson and Adams Counties, Colorado, through issuance of a Flood
Insurance Rate Map (FIRM). The Mitigation Directorate has determined that modification of the elevations
of the flood having a I-percent chance of being equaled or exceeded in any given year (base flood) for
certain locations in this community is appropriate. The modified base flood elevations (BFEs) revise the
FIRM for the community.

The changes are being made pursuant to Section 206 of the Flood Disaster Protection Act of 1973 (Public
Law 93-234) and are in accordance with the National Flood Insurance Act of 1968, as amended (Title xm
of the Housing and Urban Development Act of 1968, Public Law 90-448), 42 U.S.C. 4001-4128, and
44 CFR Part 65.

A hydraulic analysis was performed to incorporate a channelization project along Ralston Creek and has
resulted in a revised delineation of the regulatory floodway, an increase and decrease in SFHA width, and
increased and decreased BFEs for Ralston Creek. The table below indicates existing and modified BFEs
for selected locations along the affected lengths of the flooding source(s) cited above.

Existing BFE Modified BFE
Location (feet) * (feet) *
Approximately 840 feet upstream
of confluence with Clear Creek 5,260 5,260
Approximately 1,000 feet upstream
of confluence with Clear Creek 5,263 5,264
Approximately 2,760 feet upstream
of confluence with Clear Creek 5,277 5,275
Approximately 3,720 feet upstream
of confluence with Clear Creek 5,283 5,281
Approximately 5,220 feet upstream
of confluence with Clear Creek 5,294 5,294

*National Geodetic Vertical Datum, rounded to nearest whole foot

Under the above-mentioned Acts of 1968 and 1973, the Mitigation Directorate must develop criteria for
floodplain management. To participate in the National Flood Insurance Program (NFIP), the community
must use the modified BFEs to administer the floodplain management measures of the NFIP. These
modified BFEs will also be used to calculate the appropriate flood insurance premium rates for new
buildings and their contents and for the second layer of insurance on existing buildings and contents.

Upon the second publication of notice of these changes in this newspaper, any person has 90 days in which
he or she can request, through the Chief Executive Officer of the community, that the Mitigation
Directorate reconsider the determination. Any request for reconsideration must be based on knowledge
of changed conditions or new scientific or technical data. All interested parties are on notice that until the
90-day period elapses, the Mitigation Directorate's determination to modify the BFEs may itself be
changed.