WSP06696

• File Number: 8407.400
• Description: Platte River Basin - River Basin General Publications - Nebraska
• State: NE
• Basin: South Platte
• Water Division: 1
• Date: 1/1/1984
• Author: Nebraska Natural Res
• Title: Policy Issue Study on Supplemental Water Supplies
• Water Supply Pro - Doc Type: Report/Study

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greater detail on waler yield in each basin. II sum-
marizes flows by basIn lor the ten-year period 01
1969.78 (it is recognized that this may not be an ade.
quate periOd to portray every stream). The flows are
presented for tributaries and main-slem reaches in the
basins. Diagrams of appropriations. diversions. con-
sumptive use and flows lor the Loup, Nonh Platte,
South Platte, Platte, and Republican drainage basins
are also in Appendix A. Another approach 10 assess.
ing unused waler in Nebraska's streams can be found
in The Framework Study (Nebraska Soil and Waler Con-
servation Commission. 1971). Both approaches make
it clear that the stale has surface flows al certain points
in streams which could be used fOf supplemental water
development. The fact that close to half of this flow
originates in the generally lower elevation eastern third
of the state and that areas with higher economic poten-
tial generally occur in upstream areas to the west
presents definite economic, technologic. and en.
vironmental constrainls to its use. Use of these flows
may require structures and transmission systems Ihat
are constrained for a variety of lactors not the least of
which might be economic. However, the supply does
exist.
Water in a stream at any given time is lrom: (1)
overland runoff (flow derived from rain or snow melt
after precipitation or melt events); (2) reservoir releases;
(3) return flow tram irrigated lands or from municipal
systems; (4) water moving from the groundwater reser-
voir to the stream (base flow); or from some combina.
tion 01 these sources (Sentall and Shaffer, 1979). Most
perennial streams in Nebraska are natural groundwater
drains and those streams or specific reaches of streams
are described as gaining streams or reaches. Other
streams, or most commonly certain reaches of streams,
are described as losing, i.e., streamflow moves Irom
the stream to the groundwater reservoir or is lost to
evaporation or plant transpiration. For any given short
period of time, some reaches 01 some streams can
either be gaining or losing. Figure 3-2 identllies reaches
of streams that, on an annual basis, generally lose
water. These reaches may themselves include gaining
and losing stretches. Losses, as described above, from
the Plane River Irom south of Grand Island to the mouth
ollhe Loup River are generally balanced by gains to
the stream in Ihe same reach (Sentall, 1980).
In some circumstances flowing streams can naturally
recharge the groundwater reservoir adjacent to them
and hence can supplement the recharge Ihat comes
from precipitation. Water added to a stream by diver-
sion from another surface or a groundwater source or
released from a surface reservoir also can supplement
groundwater storage.
Surface water stored and spread for the purpose of
irrigation has increased groundwater in storage in the
irrigated areas and has provided the additional benefit
of smaller but more uniform streamflows downstream
from the developments. Such a benefit can be con.
sidered a bonus 10 waler management in Nebraska.

Purposeful attempts to store and spread or release
surface water for groundwater recharge would provide
a similar bonus.

Overland runoff is the principal component of
streamflow that can furnish supplemental surface water
supplies in most Nebraska stream basins. Major
streams In the sandhills ponion of the state receive only
minor amounts of overland runoff, so in this area such
runoff cannot be viewed as a supplemental source of
supply.

2. GROUNDWATER

Figure 2-5, groundwater in storage in the principal
groundwater reservoir, demonstrates clearly Ihat most
of the state is well endowed With groundwater. It has
been estimated that the shallow. permeable rocks in
Nebraska contain more than two billion acre-Ieet 01
groundwater, Much of this water can be and is being
used by installing wells. Figure 3-3 shows general areas
olthe state which have experienced signilicant water-
level rises above the predevelopment water level.
These rises have been caused by seepage Irom
surface-water developments (reservoirs, transmission
systems and application of water 10 Jand). This
mounding of water presents a potential source of supp-
ly tram groundwaler.
Figures 3-4 and 3-5 can be used with some areas
excepted to determine where Nebraska's groundwater
supplies might be tapped for supplemental uses. They
show areas where groundwater in storage would ap-
pear to exceed use-demands over any foreseeable
period. These areas were identified by the lollowing pro-
cedures. For each township, the Quanlity 01 ground.
water (see Figure 2-5) was compared to the maximum
irrigation development based upon land capability from
Figure 2-4. A series 01 these comparisons was

3.3