09 ‎(2)‎

• Board Meeting Date: 9/18/2007
• Description: ISF Section - Application of St. Vrain & Left Hand Water Conservancy District ‎(Case No. 1-02CW334)‎ - Pretrial Resolution
• Board Meetings - Doc Type: Memo

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Average Daily Depletions by Month to ISF Reach

Month Middle St. Vrain Creek between Peaceful
Valley and South St. Vrain Creek
( cfs )
January 0.0003
February 0.0004
March 0.0003
April 0.0005
May 0.0389
June 0.0748
July 0.0748
August 0.0592
September 0.0531
October 0.0187
November 0.0003
December 0.0003

Nearly all of the plan members within the Middle St. Vrain ISF reach occupy their cabins seasonally.
Thus, the plan members' depletions in the ISF reach during the winter months, when the reach is
historically stressed, are very low (the average depletion rate is 0.0004 cfs). The historical
streamflow records indicate that during the months of November through April, the ISF reach is
most likely to have flows less than the decreed flow rate of the Middle St. Vrain ISF water right.

The District's engineer, Mark McLean, reviewed the historical daily streamflow record for two sites
on Middle St. Vrain Creek and found that in most years, the Middle St. Vrain ISF water right (8 cfs
April I-October 31) has been satisfied from May through September. Since 1998, the average
number of October days with flows below 8 cfs was less than 6 days per year. During October, plan
members' average daily depletion rate is 0.0187 cfs. Streamflow records show that, in 2002 and
2003, both of which are considered to have been very dry years, the Middle St. Vrain ISF was
unsatisfied for a maximum of 18 days (in 2003). According to the District's engineer, it is likely that
October lawn irrigation, if any, occurs in the first half of the month. Projected depletions in the
second half of October, when streamflows are lowest, are estimated at 0.003 cfs.

The District's plan provides water to the basin to offset numerous small, previously unreplaced
depletions. On Middle St. Vrain Creek where the District has no replacement sources, most of the
plan members' depletions predate the December 11, 1987 appropriation date for the CWCB's ISF
water right. The plan members' depletions have occurred and have not been administered
historically, mostly because the plan members are predominantly cabin owners with seasonal,
limited irrigation and domestic water uses. Without the District's plan, it is almost celiain that the
depletions would continue and would not be administered. The District attempted to identify which
of its plan members may have been diverting in the Middle St. Vrain ISF reach prior to December
11,1987 (appropriation date of the Middle St. Vrain ISF water right). As a result of its effOlis, the
District has provided an affidavit from John D. Tipton, Jr., the fonner assistant water commissioner
of District No.5, in which Mr. Tipton states that most of the homes in the Raymond/Riverside area
had been around for 50-60 years. (See affidavit attached to this memo). In support of Mr. Tipton's

Flood Protection. Water Project Planning and Finance. Stream and Lake Protection
Water Supply Protection. Conservation Planning