Estimating Additional Water Yield From Changes in Management of National Forests in the North Platte Basin

• Description: An Independent Report Prepared for the Platte River EIS Office U.S. Department of the Interior Related to Platte River Endangered Species Partnership ‎(aka Platte River Recovery Implementation Program or PRRIP)‎,
• State: CO
• State: NE
• State: WY
• Basin: North Platte
• Water Division: 6
• Date: 5/12/2000
• Author: Charles A. Troendle, Matcom Corporation & James M. Nankervis, Blue Mountain Consultants
• Title: Estimating Additional Water Yield from Changes in Management of Ntional Forests in the North Platte Bains, Final Report
• Water Supply Pro - Doc Type: Report/Study

reflection of a higher average precipitation on the acres Suitable for Timber
Harvest than for the cover type as a whole.
Table 11 presents a summary of the water yield increases by period, for each
of the forest types. Based on the data in Table 11, one can assume that
managing the 502,000 acres of NFS land on a 120 -year rotation, using a
silvicultural alternative most appropriate to each forest type; additional
37,000 acre -feet of water could be realized by the year 2015. Maintaining
the proposed rotations could result in a sustainable increase in water yield of
50 to 55,000 acre -feet of water per year by mid - rotation. Increases or
decreases in the area considered Suitable for Harvest would result in a
proportional increase or decrease in the potential flow change. The long-
term potential increase equates to 0.11 acre -feet of water, or 1.3 inches, per
acre of Suitable land. If, for example, the 227,000 acres of NFS land
currently considered Tentatively Suitable for Harvest were included in the
management rotation, another 16,000 acre -feet of water could be realized by
year 2015.
The estimate of 50 — 55,000 acre -feet of water represents the increase in
flow that we estimate can be attained through reasonable and prudent
management. However, at least 12 percent of all NFS forested lands are
below complete hydrologic utilization and these will continue to deplete the
water resource as they mature. In the near term (next 30 -50 years) the
simulated increases will be offset, somewhat, by recovery in the younger,
existing stands.
Table 11: Potential increases in flow on the North Platte River Basin
resulting from timber harvest.
Specie
Base Water Yield in
Inches
Water Yield Increase
in Inches
.Average Increase Per Year
in 2015 (ft acre -')
2001
2005
2015
Lodgepole Pine
11.1
11.1
11.4
12.0
26,650
Spruce -Fir
15.7
15.7
16.0
16.6
9,321
Aspen
13.3
13.3
13.7
14.5
727
Ponderosa Pine
1.2
1.2
1.2
1.2
0
Limber Pine
8.6
8.5
8.9
9.5
7
Douglas Fir
12.0
12.0
12.2
12.6
38
TOTAL
36,743
41