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2 I I I I I I I I I I I I I I I I I I I Table 1. Results of water samples collected at the FRH on February 15, 1990, for heavy metals analysis by Colorado Division Of Wildlife Toxicology Laboratory, Fort Collins, CO. METALS (ppb) SOURCE DATE TEMP. of Ag Cd Cu Fe Mn Ph Zn Well Water 02/15/90 53 0.1 <0.1 2.3 <100 <20 <1.0 15.0 Heated Water 02/15/90 115 <0.05 <0.1 81.0 <100 <20 <1.0 16.0 Alkalinity FRH well water ranged from 215-225 ppm CaC03. Hardness FRH well water ranged from 260-270 ppm CaC03. Heavy Metals Due to concern with use of copper for water lines and heater coils, incoming well water (@530 F), heated water directly out of instantaneous heaters (@115 0 F), and mixed water in the rearing tanks (@700F) were analyzed for concentrations of heavy metals. Findings can be reviewed in Table 1. Colorado Division of Wildlife's toxicologist, Patrick Davies, stated that, with the hardness ofFRH water and mixing with cold water, the levels of copper and other metals found were not high enough to cause concern. Davies also noted that calcium precipitate would line the inside of the copper water lines with extended use and act as an additional buffer to copper leaching into the water supply (patrick Davies, Colorado Division of Wildlife, personal communication). TREATMENT OF INCOMING WATER Aeration-Oxygen Injection and Nitrogen Gas Removal Well water at 530 F supplies the FRH. This water is low in oxygen (5-5.5 ppm) aild high in nitrogen gas (110-114 %) as it comes from the well. This water was subjected to three treatments to remedy these gas levels. First, the well water flows through a series of packed columns (three columns each 8 inches in diameter and 6 feet long, filled with 2-inch Koch rings) placed inside a concrete spring box located outside the hatchery building. This treatment increases the oxygen to 6.5 ppm and decreases the nitrogen gas to 106-110%. Second, inside the hatchery, an oxygen generator (AS-12, AirSep Corp., Buffalo, NY) supplies pure oxygen at 3 liters per minute, which is injected directly into the cold water supply line contained in packed columns made from 5-foot long. sections ofPVC pipe 4 inches in diameter and filled with 2- inch Koch rings attached to every cold water outlet. Third, each individual tank had its separate air. supply via atmospheric air injected through airstones connected to a line from an aquarium pump (Whisper 800, Willinger Bros. Inc., Oakland, New Jersey). The combination of these three water treatments increased the oxygen to 7.5- 8.6 ppm and reduced the nitrogen gas to less than 103 percent for 68-700 F. water. .