FLOOD10343

• County: La Plata
• Stream Name: Pine River
• Basin: San Juan/Dolores
• Title: Pine River Flood Plain Study
• Floodplain - Doc Type: Correspondence

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Reply to
AttenJion of

DEPARTMENT OF THE ARMY
ALBUQUERQUE DISTRICT, CORPS OF ENGINEERS
4/01 JEFFERSON PLAZA, NE
ALBUQUERQUE, NEW MEXICO 87109-3435
FAX [phone]

March 18. 1999

RECEIVED
MAR 2 2 1999

Engineering and Technical Services Division
Planning and Environment Branch

Colorado Water
Conservation Board

Mr. John Liou
Region VITI Director
Federal Emergency Management Agency
Denver Federal Center, Building 710
Box 25267
Denver, Colorado 80225-0267

Dear Mr. Liou:

Based on a request from La Plata. County, the U. S. Army Corps of Engineers (Corps),
Albuquerque District, has initiated a flood plain delineation study for the Los Pmos River in La
Plata County, Colorado, under authority of the Flood Plain Management Services Program. The
study reach extends approximately 14 miles from Vallecito Reservoir, south to the Southern Ute
Reservation boundary, and will provide flood plains for the 0.20/0-, 1.0%-, 2.00/0-, and 10.00/0-
chance events.

Upon completion of the detailed study, La Plata County representatives would like to
submit the information to the Federal Emergency Management Agency to serve as the basis for a
revision of the La Plata. County Flood Insurance Rate Map (FIRM). Community Number 080097.
The current La Plata County FIRM contains approximate Zone A designations for most of the
Los Pmos River flood plain, and the County would like to have detailed flood plain information
for emergency and planning purposes.

The Corps has completed the hydrologic methodology, and the hydrology bas been
approved by representatives of La Plata County; the Colorado Water Conservation Board; and the
U.S. Bureau of Reclamation, Durango Projects Office. We are submitting the hydrology for your
review before we proceed with the hydraulic analysis. The enclosed notebook contains a brief
report describing the hydrologic methodology, unit hydrograph and rainfall data, and a computer
diskette containing the HEC-l models for the frequency events.

Sincerely,

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If you have questions or would like additional information, please call Ms. Bet Lotosky,
of my staff, at [phone].

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Frank: Jaramillo, P.E.
Chief, Hydrology and Hydraulics Section

Enclosure