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:~ November 20,2003 Colorado water development proposals-myths vs. realities Bia Straw ProDosal Mvth CDNRJs Big Straw Study sponsors have assumed Colorado courd and should pump back its currentry wasted Colorado River Compact rosses from near the Utah border~ They claim west slope cities, farms, and environments need all current wet year flood flows for beneficial consumptive and recreational needs. They also assume Big Straw can pump Colorado River return flows at a constant day-to-day, year-to-year flow rate, without large new reservoirs at both ends of the pipeline. Realitv Colorado River outflows at the Utah border vary from two to eight mHfjon acre- feet during droughts and heavy snowmelt years. West srope consumptive and non- consumptive users need only a small fraction of Cororado's normal and above normar- outflows. Big Straw can not physicaJly return Cororado's wasted outflow entitlements at a constant pumping rate, without massive new flood and drought regulatjng reservoirs at both ends of the piperine. Without this additional storage, Big Straw's continuous pumping would dry up the Colorado River during droughts, and increase reseNoir spilling and river flooding throughout the region during wet cycles. ColoradoJs Big Straw Study is fataUy frawed, because its major additional storage requirements were improperly omitted from the concept and cost estimates. Colorado's Gunnison and Colorado River losses have actually been jncreasing since the early 1960s~ because of the west slope's steady conversion from irrigated farming to tourism (see attached outflow trend charts for the Cororado River Mainstream Basin and its wetter untapped Gunnison Basin Branch). CDNR's Big Straw Proposal is driven by its unauthorized, but defacto, "not one drop from the Gunnison policy", South Metro Coniunctive Use Proposal Myth Colorado!s Conjunctive Use advocates assume that hjghly successful Arizona- type conjunctive use techniques, that recharge unconsolidated gravel aquifers with settling ponds, can also be employed to recharge Denver Basin sandstone aquifers with deep wens and unused Two Forks water rights. Realitv . Some small-scale Denver Basin recharge test wells have been marginally successful. However, large scale recharge operations into Denver Basin sandstone aquifers CQuld greatJy increase users costs and technicaJ risks for the following reasons: 1) raw water treatment, injection, pumping, retreatment, maintenance, and well replacement costs would substantially increase over time; 2) unpredictable long-term chemical and biological reactions associated with treated sutface water jnjectjons into sedimentary for_mations could create serious future public health problems; 3) the slow well injection process required to recharge water-bearing sandstone would require substantial new flood and drought storage, dedicated solely to recharging well fields; 4) extreme hydraulic pressure changes within sandstone formations from r~charge injections can cause unpredictable bedrock fracturing, ground movement, and subsidence problems; and 5) use of excessive Two Forks water rights for South Metro recharge operations would further damage Colorado Mainstream and South Platte tributaries. 'which have been excessively depleted by previous Metro Denver diversions.