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OOJ8~5 35060 Federal Register I Vol. 46. No. 128 I Monday. July 6. 1981 I Noti~s Colorado's mOllt significant coal deposits and mining are lound in the northwestern pari of the State. The high quality of Colorado coal p]a~ ilUi demand (or ,team electric genera lion lInd metallurgical appliations. Ulah', cool is located primarily in the 80ulhcemtral portion of the Slale. Mining is mostly underground with cunent production abouI10 million lonl per year. Most of New Mexico's coal is in the San Juan River basin in the northwest comer of the Sla Ie. Surface mines predominate in Ihis area, producing coal fOf two nearby powerplanls. Wyoming has extensive coal deposits: rapid growth in mining ~ occurring in the Rock Spring area. Arizona does not have significant coal dcpolils. 3. Synfuels Dendopment Areas. During the assessment. sill: subareas were delineated Bsthe basi. for the conclusions presente'd in thi. report. The delineation was based on hydrographic and water management considerations and the location of base energy resource. and their s)'nfuels development potential, The synfuel. development areols shown on figure-4 are: Upper Creen Ri\'er Yampa River White River Upper Colorado River Main Stem Lower Green River San Juan River IV. Waler Resources Conditions A. Surface Water Resources (Present Conditions) The principal water supply source in the Region is surace waler. The natural surface water regime of lhe Region bas been substantially altered by the construction of over JO major reservoln having a lotal active storage of 34.5 million acre.feet [maf), Main stem reservoirs account for 29.7 maf of this tolar. with Lake Powell alone IICCOunting for Z5 maf. Nllvajo. F1aming Gorge. Fountenelle. the Curecanti Unil (Blue Mesa. Morrow Point. and Crystal). and Lake Powell reservoirs make up the Colorado RJver Slorage Project (CRSP}. These are shown on Figure 1. A major function of thC5e main stem resenioirs is to regulate flows so thai the Upper Basin States (Arizona. Colorado, New Mexico. Utah. and Wyoming) may consume their compact entitlements, yel meet their compact obliSalion. 10 deli\'er specified amounl. 01 water to the Lower Basin at Lee FelT)'. Under present stead)' slate conditions. the average \'olume of water available in storage in the CRSP system would be about 85 percent of the lotal active8torage, Depletions of surface waler by consumptive Ulel within the Region and eJl:ports from the Region average about 3.1Z maf annually under present (1975- 1976) conditions of development. Agriculture accounts for nearly 70 percent of these deplelionl and exports about ZS percent. The remaining 5 percent is dJvided among thermal power generation, support of fISh and wildlife habitat. recreation facilities, mir.eral utraction. and municipal and industrial uus_ Evaporation from CRSP ,..servoirs Is estimated to B\'cf1I8e 715.(l)O acre-feet annually, Salt concentration and loadings are the most preyalent water quality problem. in the Region. Due to the concentrating effects of water withdrawals for consumptive use or export and reservoir evaporation. the problem becomes more .evare as the water flows dOWllstrearn. Of the salt loads In the Colorado River at Hoover Dam [Lake Mead). eo percent comes from natural sources and the balance from man'. Ictivities (primllrily inigalion). Avef'llge annual Nit concenlrlltion. below Lake Mead averngcd 123 milligram. per liter (mg/I) in 1912- B. Groundwater Resources Deca.use of limited exploration and use. the extent and quality of groundwater resources in the Basin are difficult to quantify. Nonetheless. groundwater could be a significant waler supply source for some synfuels development. Primary intere9t to date has focused on the Piceance Creek structural basin. which lies in the midst of western Colorado's richest oil shale re.erves. Two artesian aquifers have been evalualed in this area. with eaUmate. of total volume ranging from z.s to 2S maf and annual recharge Irom Z3..000 to 29.000 acre-feet. Yields from existing well. vary from 100 to 1.000 gallons per minute. and concenlr.atiOllS of wS50lvt<<l solids range from 200 mg/I in the upper aquifer (0 30,000 mgll in the lower, The San JUdn development area in New Mexico also has groundwater for .ynfuels development. C. Future Depletions for Conventiollol UseiJ Regional water a\'ailability fur synfuels production was assessed againsl a baseline of projected depletions in the Region. Three levels or depletion by conventional water uses and exports were examined for the year ZOOO--a low level (4.1 million acre-feet per )'ear). a medium level (4.5 mal/year). and a high level [4.8 maf/year). For the purposes of this report. the availability of water for synfuels development is diacussed in relationship to the medium level. Projecllons for this level [fable lJ represent the State.' current esllmates of the most probable level of depletions by conventional uses and exports. Evaporation from CRSP reservoirs would be expected 10 decrease aboul4 percent from the present esllmated 715,000 acre-feet annually, The drop in slorage levels due to the greater depletions will lessen the rt'servoir surlace evaporation. Future depletions ahow three major water use trends. First. irrigaled agriculture is projected 10 continue to eJl:pand. accounting for just over 60 percent of total depletions in the year 2((10. Second exports from the Region are expected to incnase. moat notably for municipal and industrial use in the front range urban corridor in Colorado. the Rio Crande Basin in New Mexico. and the Dooneville Basin in Utah, Third. a 350 to SOl) percent increase in water use for thermal electric generation is expected. Even with these inCl'f!ases, however. thermal electric facilities would still account for o~y 1 pen:ent of the year 2((10 depletions_ y . F Tabl. t.-Pressnt MJd PmjfIcted DepletiOnS - (W~"""""!II....'_otl -. -- - '", ,- - -.. - ... -- (1,000_,"",..-1. 2.US " ", ~ ).1" m "''' .....- ~, " .. , '" '" ~ " , '" " " " , ~ n . , , " lIJIl*'CoIot____ ~_h_._ ,-- ~~.- u,p.~Rrv.-.~ y-- -- -- UIaf>__ .