NorthPlatteBasinWaterSupplyandNeedsReport

• Basin Roundtable: North Platte
• Title: Water Supply & Needs Report for the North Platte Basin
• Date: 6/1/2006
• Author: CDM
• Basin Roundtables - Doc Type: Needs Assessment Documents

Section 5
Consumptive Water Needs in the North Platte Basin
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As noted, reductions in agricultural irrigated acres may
occur due to development, acquisition for M&I needs,
dry-up for instream flow purposes, or as a result of lack
of long-term supply availability such as lack of
augmentation for well pumping or over pumping of
groundwater. As described in Section 8, not all of the
reduction in agricultural irrigated acres will result in
additional supplies available for M&I or other uses. In
addition, not all of the development of irrigated
agricultural lands for M&I use will result in a reduction of
irrigation demands. Some of the development of
agricultural irrigated acres will be for large lot residential
development of 1 to 5 acres or ranchettes of 5 to
35 acres. For many of these parcels, if the water rights
are not sold and transferred at the time of development,
there may be some continued irrigation for hay or
pasture for domestic animals kept on the properties.
SWSI Basin Roundtable feedback was mixed on whether
new residential owners would tend to irrigate as diligently
as the former rancher or farmer and whether overall
water demands would change as a result of this new
land use.

Typical water use per acre for different types of M&lland
use development in the South Platte Basin are shown in
Figure 5-6. Generally, as residential densities increase,
the gross water use per acre also tends to increase.
Figure 5-6 shows that average gross water use can
range from 1.3 AF/acre for industrial use to 3.5 AF/acre
for higher density residential uses, such as apartments.
Agricultural water deliveries and consumptive to

historically irrigated lands vary widely and are dependent
upon seniority of water rights, physical availability of
supplies, timing of deliveries, delivery losses, and
application efficiencies. The ability to use agricultural
water rights existing on the land to meet the needs of
M&I use as the land is developed is highly dependent
upon these factors, plus the need for a portion of the
water to be stored to meet non-irrigation M&I demands
and to provide for firm yield for below average runoff
years. These considerations are explained in greater
detail in Section 8.

5.2 Estimated 2000 and Projected
2030 M&I and SSI Use

Of the many factors affecting M&I water use, the
projected increases in population clearly drive the
increases in M&I use from 2000 to 2030. The effects of
Level 1 conservation result in a projected reduction in per
capita M&I water use of approximately 6 percent over
this 30-year planning period. This reduction is reflected in
the 2030 M&I water use projections presented in this
section. M&I and SSI water use projections presented in
this section represent the gross or total diversion
amount, as opposed to the consumptively-used portion
as described in Section 5.1.1.6.

To reiterate, M&I projections were developed by
multiplying the estimated (2000) or projected (2030)
populations by per capita demands for each of the state's
64 counties, then reducing water use associated with
Level 1 conservation measures for the
3.5 2030 scenario. These results were
aggregated on a basin basis, as well
as on a subbasin basis for use in the
water supply "gap analysis" as
presented in Section 8.

Multi-Family
Single-Family Medium 2.2
Density
1:- Single-Family Low
0 1.9
'" Density
.2!
"
0 Public Parks 2.0
'"
III
:J
."
!: Employment District 1.4
"
.J
Commercial 1.6
Industrial 1.3
0.0 0.5 1.0 1.5 2.0

Annual Water Use in AF/acre

4.0

Source: Cities of Westminster and Greeley and NCWCD

2.5

3.0

3.5

Figure 5-6
Estimated Gross Urban Water Demands by Land Use
(Indoor and Outdoor Use)

CONI

5-8

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