WSPC03959

• File Number: 8283.200
• Description: Colorado River Basin-Colorado River Computer Models-Colorado River Decision Support System-Ray
• State: CO
• Water Division: 5
• Date: 10/1/1995
• Title: South Platte Water Rights Management System-Water in the Balance-No 4-South Platte Water Rights Management System
• Water Supply Pro - Doc Type: Publication

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Colorado Water Resources Resean:h tnstilUte

Improving Water Administration

With the water information :!.beel.
detailed information pertaining to each
individual water district is available foc
users system.wide as W)O as commis.
siooers submit the information. ODe can
see CWTenl river 80\11$, diversions. and
extenuating circumstaDces that affect the
waler com.miss.ioners. daily decisions.
The water information ilieet provides a
snapshoc of a district's water operaucns
ratberthan an 'official' diversion record.

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The Ri,'er Call

Users knO\lo' who can diven water by
a mechanism known as the rivercall. 1be
calling right at any poinl on a stream is
the most senior right dO\l.-nslream from
thai point at ..."web a water shortage
exists, A call is Dot enforced urness a
user w-ith a senia right experiences a
shatage caused by the ac:tivitk:s of jun.
ior users u~tream.. In such situations, the
serna appropriator contacts Colorado
Division of Water Resources administra.
tive persoone.l who officially set the river
call. Administrators inform junior appro-
priators upstream that they must stop
diverting water or reduce the amount of
their diversion, leaving additional water
in the river to satisfy the senior appropri.
ator. (For more <D Colorado water law
see page 7 81 the end of this pamphlet.)
SPWRMS software keeps track of
rivetcalls, When a senior wate.r user fails
to receive adequate water to meet hisAJer
demands. that user may exercise hisiher
water right by requesling that a call be
placed on !he river. SPWRMS includes
functicnalily tocb.angc calls on the m'er,
view the current call state. and test the
effect of . De9<' call. When a senior
appropriator contacts ~ Colorado Divi-
soo c:i Water Resources to request that a
call be set. water adminiStratorS use
SPWRMS to see who will be affected by
the DeW calI,
An important feature of the system
is its kno......ledge of UPStreaJIl-dO\1.'U.
stream relationsh.ips t'oetween points 00

Terri Betancourt and Paddy McCarthy ofCADSWES al wor/.: on SPWRMS.

the river, For example. the system can
tell if one diversion structure is upstream
or OOv.nstream from another, This allows
the system to keep lfack of me call
affecting every diversion structure on the
nver system.
River calls Ilre stored in the cenual
database, This provides all users of me
system with an up-to-date representation
of the call structure fer the entire basin.

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Scenario Testing

Curtailment refen to the forced ces-
sation of diversim by junior appropria.
tors when a senior water user requests
that a call be set The curtailment analy-
sis 1001 in SPWRMS allows the system
user 00 lest hypothetical scenarios and
see the effect of changing the call at a
given diversion structure. Cunailment
analysis helps Mmini~uators avoid plac.
ing a call that is too senior. thereby cur-
tailing an excessive number of upstream
diversions, If an nnr'lH"essarily senior call
is placed. mere water comes down the
river than the calling right is able to use.
and waler is essentially wasled. Admin-

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isttators would rather find a more junior
call that curtails just the right amount of
water to satisfy the immediale water
oeerl.

Using the cunailmem analysis fea.
ture of SP\VRJ.fS, the administrator
picks a diversion point on the river where
the new call might come into effect and
then selects a number of rou=ntial calls to
test at that structure. SPWRMS lfaces
the river to see which junior rights are
currently diverting upstream frem the
new calls, If it finds any junior diver-
sions. the software calculates how long it
would t.alce water from curtailed rights to
reach the DeW calling structure. The soft-
ware also lists the rights affected under
various scenarios. telling waler Aclminic:.
trators who to contact to enfon::e a new
caJl.
SPWRMS simulates turning off cur-
tailed upsueam diversions and allov.ring
waler to 80\1.. unimpeded in the river
instead. The simulation is based 00 a
table listing the empirically derived lag
time (b0\1.' lreg it tales for water to 80'0\'
through a given stretch of river). and the
loss (bow much water is lost to seepage
and evaporation aloog a stretCh of river)
for e....ery river reach in the basin. As with