WSP06144

• File Number: 8210.470
• Description: Organizations - Pacific Southwest Inter-Agency Committee - PSIAC
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 10/1/1968
• Author: PSIAC
• Title: Pacific Southwest Inter-Agency Committee - Report of the Water Management Subcommittee
• Water Supply Pro - Doc Type: Report/Study

N d Runoff
~ e Topography

~

"

12

, f Eff. Grnd.
Cover
9 Land Type
Mgmt. Qual.

h Upland
Erosion

thaw dominant, appox 12" ppt
Hi peak flows, low volumes
60% area 15% slope = 9.0%
40% area 8% slope = 3.2%
Weighted slope Ave." 12%
Veg 20, Litter 15%, Rock 10%
Total Eff. Grnd. Cover- 45%
Hist. overgrazed, impacts
under control, land treatment
.practices implemented '
>25% of area involved in
cone. flow eros, with gullying
controlled
Moderate flow depths, eroding <,
banks and bed controlled, 4th
order ephemeral gully develop.
controlled

6

7
4

6

-1

-5

i Channel
Eros. and
Sed, Trans.

10,

Subtotal a-g = 24; Subtotal h-i = 16 '

Total Rating = 40

The rating of 40 points is a sediment yield of 0.35 aC-ft/sq. mi.
9r approximately 1.1 tons per acre. The average annual salt yield
rate is .09 xLI tons per acre =0.1 tons per acre salt. The
annual salt yield from the geomorphic unit is as follows:
0,1 tons/acre x 1760 acres x .9 (SDR) = 158 tons of salt (FWP).

For planning purposes, the annual salt benefit. vaiue for the
geomorphic unit is the FWOP value of 542 tons minus the FWP value
of 158 tons fora net benefit value of 384 tons of salt.

For planning purposes, the annual sediment benefit values are
calculated as follows:

6019 tons (FWOP) - 1742 tons (FWP) = 4277 tons
3.2 ac-ft (FWOP) - .9 ac-ft (FWP) = 2.3 ac-ft.

Modification 16: It is proposed that the factor rating sheet on an
unnumbered page in the original PSIAC text be replaced with the two
page "PSIAC Sediment Yield Factor Rating Sheet" attached to the end