DWR_4151797

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

R
_ SOUTH PLATTE BASIN
Basinwide Conditions Assessment:
The SWSI value of -0.7 indicates that the overall SURFACE WATER SUPPLY INDEX
conditions are slightly below normal. Reservoir storage, the Basin
S South PlattePlatte "«
key component in this basin in computing the SWSI value, 4_
was 98% of average on May 1, 1991. Storage in the plains -L. , ' '
reservoirs in the basin increased by 6,300 acre-feet for the 3 ?'- =
month. With the exception of Cheesman and Spinney - L �- �—d lf.'‘''!7—d — 1
Mountain Reservoirs which are at 72% and 39% capacity 1 1- �' ' '"
respectively, storage is at or near capacity. Precipitation was i °only ---
78%of average for the month and is only73%of average Iii p--1
g
for the water year. Basinwide snowpack increased to 84%of
a _2
average. Snow water equivalency is approximately 18 inches.
Snowpack is lowest in the St. Vrain drainage at 59% of 3-
average. Flow at the key gaging station, South Platte River
JANB1 JANB2 JAN03 JAN64 JAMS JAMS JAN�7 JAMS JANGS JANGO JARS/
near Kersey, averaged 299 cfs for the month as compared to MdITW TEAF
the historic monthly average of 1021 cfs. Flow at the
Colorado/Nebraska stateline averaged 262 cfs for the month,
down from 386 cfs the previous month. Some ground water
recharge projects continue to operate.
SOUTH PLATTE RIVER NR. KERSEY
Outlook: now Gr WATER YEAR
°°
Although snowpack increased at higher elevations
(above 9000 feet), lower elevation snowpack is nearly totally s°°
diminished. This condition, along with c000ler than normal 1 300 .
temperatures has resulted in low early runoff. The streamflow I
forecast is lowest in the Cache la Poudre drainage at 73% of s ll '°°
average and highest in the Bear Creek drainage at 93% of .g 3�
_V
average. 8
200
Administrative/Management Concerns: 100 .
The interstate compact with Nebraska adjusted on
April 1st,basically requires Colorado to provide a minimum of °
Oct Nov Dec Jan Feb March Avid
120 cfs at the Colorado-Nebraska stateline. The river call for .ONTH
0 reT c11337 + OFT c19647 a AVE. A 1SS1
District 8 (South Platte River above Denver) was changed to
the Cheesman Reservoir storage right (June 27, 1889 decree)
on April 2, 1991. This call affects administration of the upper
South Platte basin. The Burlington Ditch diversion right
(November 20, 1885) was implemented on April 4, 1991. South Platte Basin Reservoir Supp I i es
220
Public Use Impacts: T.°_-'
Public water use should be relatively normal. Flow in ISO
170
the reaches of the South Platte River immediately below i 1:
Spinney Mountain Reservoir and Cheeseman Reservoir are at ii-e //�\ [�
40 cfs and 240 cfs,respectively. Storage in Spinney Mountain ! 120�� ��
i110
Reservoir was 20,855 acre-feet on May 1, 1991. Storage :g 100
commenced on May 1, 1991, as in-stream storage rights went 7O,
into effect and Homestake transmountain water deliveries s 60 77
began. s.40 V
° fig\ //�
Dillon Horptooth Eleven Mlle Chaaanrn Jackson Garr Lake
® Avg. 4,30 Contents ® 4/3Wa1 Contents
3