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. 596 UNIVERSITY OF COLORADO LAW REVIEW [Vol. 59 The modest cost to GASP members (essentially 90 cents per acre- foot of groundwater pumped) has been made possible in part by the informal way in which GASP operates. Only relatively recently has GASP been providing much of the data it promised to the state engi- neer in 1972. In addition to the amount of groundwater pumped dur- ing the preceding period, the amount of acreage irrigated, and a projection of the amount of groundwater to be pumped during the next period, the state engineer now wants GASP to provide detail re, garding cropping patterns and other information to enable a more complete analysis of the effect of GASP members' groundwater pumping. B. The Fort Morgan Plan for Augmentation Rather than operate under the GASP umbrella some well owners in the South Platte Valley have opted to protect their well operations by means of a plan for augmentation. Such an approach places these appropriations directly and permanently within the state priority sys- tem. An example of this approach is provided by the plan for augmen- tation developed by the Fort Morgan Reservoir and Irrigation Company ("Fort Morgan") and approved by the Division One Water Court in 1985.66 The Fort Morgan Reservoir and Irrigation Company is a mutual ditch company providing water to about 11,000 acres offarm lands in Morgan County, Colorado,67 Fort Morgan has a direct flow decree for 323 cubic feet per second with a priority date of October 18, 1882. In addition it owns 1,030 shares (of the 1,550 total) of the Jackson Lake Reservoir Company, a mutual company which owns and oper- ates Jackson Lake Reservoir. The storage capacity of this reservoir is about 30,000 acre.feet, Members of the Fort Morgan Company also use wells as a part of their irrigation water supply. Most of these wells were adjudicated in 1974 but because of their junior status could not operate except under some kind of augmentation plan. Under a provision then available in the law these wells were permitted to operate under a "temporary" plan for augmentation.6' During this period Fort Morgan collected 66. In re Fort Morgan Reservoir and Irrigation Company, No. W.2692 (Water Division No. I. Colorado. April 22. 1985) {hereinafter Fort Morgan Decree]. 67. The background information provided here comes from the engineering study performed by HRS Water Consultants, Inc., Fort Morgan Reservoir and Irrigation Company Plan fOf Augmenta- tion, (January 1985) (hereinafter Fort Morgan Report]. 68. Temporary augmentation plans were authorized by a 1974 law, S.B. 7, 1974 Colo. Sess. Laws 440, ch. 111. The state engineer was given authority to approve such temporary plans pending final court action. This section was repealed in 1977 by S.B. 4, 1977 Colo. Sess. Laws 1702, ch. 483, ~ 6, , t988] COLORADO LAW OF "UNDERGROUND WA~ 597 data on its total water demand to grow crops, its surface supply, and members' groundwater use. It also implemented its program for pro- viding augmentation water. By 1985 Fort Morgan thought it had the data necessary to support its request for a final plan for augmentation. The court decree approving this augmentation plan is viewed by many as providing a model for bringing irrigation wells into the prior. ity system. There are two critical aspects to this plan: calculation of depletions to the stream attributable to the pumping of Fort Morgan member wells, and operation of the replacement scheme to offset those depletions, To calculate depletions, the analysis in support of the plan first calculated the average annual irrigation water requirement for the Fort Morgan lands between 1960 and 1980.69 Using diversion records for direct flow and reservoir deliveries the annual surface water supply was then determined.70 Groundwater use represented the difference between surface supplies and crop requirements,7I The effect to the river from this pumping was calculated using the "stream depletion factor" value for each well. This factor indicates both the .amount of loss to the stream from well pumping and the timing of that 10ss.72 The Fort Morgan replacement plan is based primarily on a recharge program. Under this program, water is diverted from the South Platte under a 1972 priority and carried to several recharge lo- cations." Surface flows brought into these recharge areas are mea- sured on a daily basis. Evaporation losses are calculated as well as any flows out of the recharge sites, The difference is considered to recharge the groundwater aquifer. Accretions to the stream from these recharge efforts are then measured against depletions to the stream resulting from groundwater pumping,74 The result is the "net stream effect." For the recharge program to fully offset the effects of well pumping, accretions must at codified at COLO. REV. STAT. ~ 37.92.-305(8) (1973). See MacDonnell, Plans for Augmentation: A Summary, in TRADITION, INNOVATION, AND CONFLICT: PERSPECTIVES ON COLORADO W ATEa L....w 147 (L. MacDonnell ed. 1987). 69. Crop records as well as acreage inV()lved are maintained by Fort Morgan. The Blaney-Crid- die method was utilized to calculate the water requirements for these crops. Fort Mo~n Report, supra note 67, at 3. 70. Surface supplies were further adjusted to account for water losses between the headgate at the river and application to the crop. Fort Morsan Report, supra note 67, at 4, 11. Actual groundwater pumping appears to be nearly twice the COP511mptlve use amount calcu- lated. Pumping between 1977 and 1980 was reported to be 6,152 acre-feet per year; the calculated groundwater use for this period was 3,811 acre.feet per year. Fort Morgan Report, SUprtl note 61, at S. 72. See the discussion of the stream depletion factor, supra nOte 1. 73. Those sites include the Fort Morgan canal itself, a generally dry streambed known 8$ Badger Cretk, and several ponds. The total recharge capacity of these sites is estimated to be 13.0CI0 acre-feet per year. Fort Morgan Report, supra note 67, at 5. 74. The stream depletion factor also is used to analyze accretions to the stream.