FLOOD00270

• County: La Plata
• Community: Bayfield
• Stream Name: Pine River
• Title: Floodplain/Floodway Study Pine River Subdivision
• Date: 6/23/1986
• Prepared For: Pine River Cattle Company
• Prepared By: Harris Water Engineering
• Floodplain - Doc Type: Floodplain Report/Masterplan

1..

PINE RIVER CRTTLE COMPRNY

FLOODPLRIN/FLOODI^IAY STUDY
PINE RIVER SUBDIVISION

PURPOSE OF STUDY

This report is prepared for the Pine River Cattle Company
r..p,'esented by M,'. F,'ar,k Fo,'bes, 8785 County Road 501" Bayf ie Id,
Colorado 81122. The Pir,e River CattlE. Compar.y is ir. the process of
subdividing a portion of its land along the Pine Rive~ in Section
3'+, Rar.ge 7 West, Township 35 North. The map or. the following page
shows the subdivision. Since the subdivision is in the floodplain
of the Pine River, the LaPlata County Planning Department has
requested informat ion on the areal extel~t and the depth of water for
the 100 year flood.
The narrative bele,w describes the en[jinee,'ing evaluatior,s
conducted to estimate the potential flooding on the Pine River in
the area of the proposed subdivisior.. The fi,'st section describes
the existing conditions and the subdivision_ The second section,
"Flood Estimation" describes how the 100 year flood flow was
el,:;timated. The third section, lIFlood Inunda.tion", describes the
areal extent and the depth of w.ate,' during the 100 year flood
occurance at the proposed subdivision.
The information and evaluatior.s cor.tainecl in this report was
p,'epared strictly fOl" the use 'of the Pine Rive,r Cattle Company for
the subject subdivision. Use of this report by any other person,
group, or organization is at their own risk and Harris Water
Engineering cannot be responsible for those uSeS.

SUBDIVISION SETTING

The proposed subdivision is located on the Pine River about 8
mi les no,'th of the Town of Bayfield and about 4 mi Ie's south of
Vallecito Dam. The elevation of the subdivision is about 7350 feet
MSL. The subdivision is located 1n a sect ion of the r'iver whe,'e
there are two channels; the majo,' ('easterril channel is the main
channel for the Pine River and carries most of the flow, the smaller
(western) channel has about 10% of the capacity of the other. The
two channels form an island that is about one half mile long and 500
feet wide on the average. . The island is heavily cove,'ed with
cc,ttonwood trees and b,'ush.
The subdivision would separate four lots from the main part of
the Pine River Ranch properties; the lots would be on or partially
on the island between the two channels. One lot is on the north end
of the island at the point where the two channels separate from one
channel. This lot is totally on the island. The other three lots
begin about 500 feet downstream from the north lot and straddle the
small channel. These three lots ar'e located half on the island and
half on the land to the west of the small channel.
The drainage area above the subdivision is about 260
miles in size and the longest water COUrse (the Pine River)

square
is 34