DWR_4151798

• Title: APRIL 1991 SWSI: COLORADO WATER SUPPLY CONDITIONS UPDATE, SURFACE WATER SUPPLY INDEX
• Year: 1991
• Document Type - Publications and Reports: SWSI Monthly Report

. SOUTH PLATTE BASIN
Basinwide Conditions Assessment:
The SWSI value of -0.9 indicates that the overall SURFACE WATER SUPPLY INDEX
River gew
conditions are slightly below normal. Reservoir storage, the 5 S°"'"P'"" '"
key component in this basin in computing the SWSI value, ,-
:4( .
was 106% of average on April 1, 1991. Storage in the plains . 3- ; ; .
reservoirs in the basin increased by 7,000 acre-feet for the a `' ' ' .:�
month. With the exception of Cheesman and Spinney - - SI`' •- 1
Mountain Reservoirs which are at 69% and 41% capacity $ - -' ' -; - = ."
respectively, storage is at or near winter operations capacity. i a - = - T—
Cheeseman and Spinney Mountain Reservoirs are currently .,- L TA r7
providing water supplies to Aurora and Denver. Precipitation
a -2-
was only 37% of average for the month and is only 72% of
average for the water year. Basinwide snowpack is only 75% 3-
of average. Snow water equivalency is approximately 15 _
JAN91 JAN92 JAN63 JAN94 JAWS JAN96 JAN97 JAN99 JAN99 JANRI JANY1
inches. There is still time for the snowpack to improve as the MONTW YEAR
peak accumulation typically doesn't occur until around May
1st. However,the March storms that provided heavy snow to
much of the state had minimal impact on the South Platte
Basin. Snowpack is lowest in the Big Thompson drainage at
65% of average. Flow at the key gaging station, South Platte SOUTH PLATTE RIVER NR. KERSEY
River near Kersey, averaged 559 cfs for the month as 450 FLOW BY
"" '"gA"
compared to the historic monthly average of 826 cfs. Flow at
the Colorado/Nebraska stateline averaged 386 cfs for the
. 550
• month, down from 639 cfs the previous month. The majority !
._________Z
of ground water recharge projects are operating at near s '°°
42
capacity. a 2 250
•
• t 4 200
Outlook:
1so r
Even with above normal precipitation in April in the
100
basin, snowpack going into the 1991 runoff season will likely
-------------
be 30% below normal. The streamflow forecast is lowest in 5 __------r
the Saint Vrain Creek drainage at 63%of average and highest 0
act Nor O.c Jan Feb M.rch
in the Bear Creek drainage at 87% of average. MONTH
a 22T 0993, * ear(1s94) O AVO. A 1281
•
Administrative/Management Concerns:
The interstate compact with Nebraska adjusted on
October 15 basically giving Colorado full use of available
streamflow until April. District 2 (South Platte River between South Platte Basin Reservoir Supplies
Denver and Greeley) went to the Burlington Ditch right 220 -
(November 20, 1885) from March 25-28, 1991. The river call 2a �
for District 8 (South Platte River above Denver) was changed
to the Denver South Platte River secondary intake right i 19a A
(December 6, 1910 decree) on March 6, 1991. This call I 14o
affects administration of the South Platte River above the a 120 A
Denver intake at Strontia Springs Reservoir up to the h g 1Q0
headwaters in South Park. The Denver Water Department o
27A.
Chatfield Reservoir call (December 12, 1977) implemented I -A
was released on March 20, 1991. f
Public Use Impacts: O
Onion N.latooth EI.V.n ell. Chairmen Jackson Barr lake
Public water use should be relatively normal. Flow in
the reaches of the South Platte River immediately below ® .. ""`°"""" 1=1y31/21 Contents
Spinney Mountain Reservoir and Cheeseman Reservoir are at
110 cfs and 84 cfs, respectively. The storage in Spinney
Mountain Reservoir was 22,155 acre-feet on April 1, 1991. Storage will commence on May 1, 1991,as storage rights go into
effect and Homestake transmountain water deliveries begin.
3