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<br />0921 <br /> <br />The groundwater system on NOSR 1 consists of four principal water- <br />bearing zones. Zone 1 is found in the upper part of the Parachute Creek <br />Member above the Big Three rich zone. This water-bearing zone, with an <br />, <br />average thickness of about 170 feet, is generally unconfined, in contrast <br />to the lower zones. Calculated transmissivities range from a high of 449 <br />ft2/day in Well 22, to a low of 1.2 ft2/day in Well 15/16. With the <br />exception of Well 22, all calculated transmissivities are very low and fall <br />in the permeabili~ range of siltstone. Aquifer response to the drawdown/ <br />recovery tests are characteristic of fractured reservoirs and indicate that <br />this zone is a limited aquifer which could be pumped dry in a short period <br />of time with a large pump. Zone 1 groundwater can be classified as calcium <br />bicarbonate at Well 24, mixed-cation bicarbonate at Wells 17, 18, and 22, <br />and sodium bicarbonate at Wells 15/16, 20, and 26. These water ~pes are <br />generally found in recharge areas in the Piceance Creek basin. The <br />dissolved solids concentration and the specific conductance values for the <br />Zone 1 analyses indicate that all but the sample from Well 20 satisfy <br />federal drinking water standards and ,that Zone 1 water is safe for agricul- <br />tural use. In the sample for Well 20, iron is high at 5.8 mg/l, fluoride <br />is elevated at 1.6 m9/1, and specific conductance is 1000 micromhos/cm. <br /> <br />Zone 2, located in the viCinity of the "AU Groove, has an average <br />thickness of 20 feet. Calculated transmissivities for this zone range from <br />0.9 to 105.9 ft2/day. Response to testing indicated that this zone is a <br />limited aquifer, with several tests resultin9 in the complete drawdown of <br />the zone in less than 10 minutes. Water in Zone 2 is either mixed-cation- <br />bicarbonate water or sodium-bicarbonate water. The highest current ratio <br />of dissolved solids is found in Well 15/16 and the lowest in Well 21. <br />Among trace constituents, only fluoride was found in significant concen- <br />trations with values ran9ing from 0.3 mg/l at Well 18, to 3.5 mg/l at Well <br />15/16. The water in Zone 2 does not exceed drinking water or agricultural <br />use standards at Wells 18 and 21, but Wells 15/16 and 17 have a medium <br />sodium and salinity hazard, and exceed drinking water standards for <br />dissolved solids (Well 15/16), and fluoride (both wells). <br /> <br />Zone 3 is located in the viCinity of the B-groove. This zone has an <br />average thickness of 70 feet and has somewhat higher calculated transmis- <br />sivities and hydraulic conductivities than those for the other three zones. <br /> <br />1-3 <br />