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t <br /> Date: April 18,2016 <br /> To: Governance Committee(GC),Water Advisory Committee(WAC) and Executive <br /> Director's Office(EDO) of the Platte River Recovery Implementation Program <br /> (PRRIP) <br /> From: Jon Altenhofen, Colorado Water User Member,WAC <br /> Memo Subject: Colorado's Annual Report for 2015 for Tamarack 1 <br /> Colorado's Initial Water Project (Tamarack 1)—Annual Review 2015 <br /> The Colorado Tamarack I Project based on the historic study period of 1947-1994 developed an <br /> average annual yield of 10,000 acre-feet of target flow shortage reduction. This yield is the result of <br /> diversions to managed groundwater recharge sites during times when the river flows are in excess to <br /> target flows. The accretions returning to the river later from these diversions are credited to <br /> Tamarack 1 during times of shortage. As with the CPFD (Colorado Plan for Future Depletions) <br /> operations, SPWRAP operates and pays electrical costs and maintains dedicated recharge projects <br /> (i.e., Tamarack Wildlife Area and Heyborne projects) and pays for Tamarack 1 creditable accretions <br /> not used by existing recharge plans. South Platte Water Related Activities Program (SPWRAP)is a <br /> non-profit group of mainly municipal Colorado water users collecting assessments ($0.90 per tap in <br /> 2015)to pay for Colorado's water obligations for PRRIP in partnership with the State of Colorado <br /> where the State covers other Program costs. For 2007-2015, SPWRAP paid a total of about <br /> $4,600,000 for CPFD and Tamarack 1 creditable supplies. The table below shows the Tamarack 1 <br /> credits actually developed from all these operations since the start of the PRRIP in January 2007 <br /> with an average annual yield of 7,859 acre-feet for the years of full operations. <br /> The 10,000 ac-ft goal has not yet been reached on average because the flow frequency for excess to <br /> targets has been less for the starting years of PRRIP as compared to the historic period. December <br /> through March are the months of greatest excess and for the historic period of 1947 through 1994, <br /> 59%of these months had excess flows above target flows. However for the first 9 years of the <br /> Program for December through March, only 35% of these months had excess flows,thus limiting the <br /> amount of water available for Tamarack 1 operations. An estimate of the Tamarack 1 credit <br /> achievable if actual flows similar to historic excesses had occurred for the beginning years of the <br /> Program can be estimated as follows: divide the actual 7,859 ac-ft average in table below by the <br /> water availability ratio of 0.59 (-35/59)which results in 13,320 ac-ft. <br /> The Program document recognizes the possibility that reductions in actual yield might occur in <br /> paragraph IIIC of the Tamarack 1 description in PRRIP Attachment 5 Section 3 which states"...as <br /> long as Tamarack 1 is constructed and operated as described herein,the target flow shortage <br /> reduction credited to Tamarack 1 individually or to the three initial water projects collectively will <br /> not be reduced even if the real time frequency and magnitude of flows in excess to targets at Grand <br /> Island causes Tamarack 1 to produce an average annual yield that is less than that projected under <br /> historic flow conditions,regardless of the reasons for the change." <br /> 1 <br />