WSP09768

• File Number: 8143.700
• Description: John Martin Reservoir - Annual Operating Plans and Reports
• State: CO
• Basin: Arkansas
• Water Division: 2
• Date: 12/1/2003
• Title: Annual Report of the Operations Secretary - Concerning the Operation of John Martin Reservoir - 2003
• Water Supply Pro - Doc Type: Annual Report

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Beginning on November 16, 2002 and pursuant to the provision of Section III (a.k.a. Article III)
of the 1980 Operating Plan, the storage of certain other inflow was also credited to the winter
water account. Storage into the winter water account continued to March 15, 2003, when the
distribution of 12,572 acre-feet occurred to the appropriate accounts pursuant to Section III D of
the Plan. This included a transfer of 23 76 a.f. of water into the transit loss account consisting of
676 a.f. to make up for deficits detemrined pursuant to Section II E (4) and 1700 a.f. to complete
the fill of the transit loss account. An explanation of this operation is documented in a letter to
the Assistant Operations Secretary, Mr. Mark Rude, dated March 19, 2003.

The division of inflow between conservation storage and the winter water accounts followed
established guidelines and resulted in an approximate overall 49 -to- 51 split (conservation to
winter water) [See Section 2 -Tables I and II]. The methodology for determining the
conservation storage to winter water ratio was consistent to the method utilized in prior years.
The base flow at the Arkansas River at Las Animas gage was detemrined during the period
November. 8th through November 14th with current meter measurements conducted by DWR on
November 12th and by USGS on November 14th. The base flow was detemrined to be 12.14 cfs.
During the period November 15th through November 18th computations were made to determine
the enhanced flow associated with arrival of winter water at the gage. Additional current meter
measurements were conducted on November 18th and November 20th by DWR and on November
22nd by the USGS. The enhanced flow during this initial transition period was determined to be
30 cfs and an initial ratio for winter water and conservation storage was set at 59.5% for winter
water (17.86/30) and 40.5% for conservation storage (12.14/30) for the flow through the
Arkansas River at Las Animas gage,

A significant operational change in the winter water program occurred November 17th when the
Fort Lyon Canal ceased diversions at the main canal headgate, resulting in an increased flow at
the Arkansas River at Las Animas gage two days later on November 19th. Therefore, a second
transition period was established over the period November 19th through November 21" and the
new enhanced flow was detemrined to be 59 cfs. This resulted in a winter water ratio of 79.4%
(46.86/59) and a conservation storage ratio of 20.6% (12.14/59). Since there were no further
operational changes that significantly affected the winter water ratio during the remainder of the
2002-2003 winter water program, these ratios were used until the end of the winter water storage
season on March 14, 2003,

For the period November 1, 2002 to April 1, 2003, conservation storage accumulated 11,867
acre-feet. The winter water inflow accumulation to the conservation pool did depart from the
1950 to 1975 average historic winter storage amount of22,209 acre-feet. In the 2002 Operations
Secretary's Report documentation was provided as to the severity of the drought effects on 2002
water supply as measured through the Arkansas River at Canon City gage. The reduced inflow to
Pueblo Reservoir and John Martin Reservoir due to the effect of the severe drought caused an
overall reduction in the Wmter Water storage program and conservation storage in John Martin
Reservoir,