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<br />P,:1": 7~7 <br />uu.!. v. <br /> <br />New Mexico Game and Fish personnel verbally indicated dissolved oxygen varied from <br />approximately 9,0 to 6.4 during the day, with the low readings occurring during the early <br />morning hours before sunrise, Data submitted for the low flow test report indicated temperature <br />averaged 14.4oe with 26 readings (out of 292) above 200e (standard for high quality coldwater <br />fishery). Dissolved oxygen averaged 9,0 mg/L with 12 readings (out of 291) below 6.0 mg/L <br />(standard for high quality coldwater fishery) and pH averaged 7.9 standard units with 35 readings <br />(out of 287) less than 6,6 or greater than 8,8 standard units (standard for high quality coldwater <br />fishery). <br /> <br />The Reclamation biology team took water quality readings at 77 locations between Navajo Dam <br />(approximate river mile 225) and Salmon Ruin (approximate river mile 187), which includes <br />most of both river segments 20,6.4.401 and 20.6.4.405, The readings included conductivity, <br />temperature, and dissolved oxygen. The following paragraph is taken from the Executive <br />Summary of the Assessment of Aquatic Habitat of the San Juan River. <br /> <br />Readings were taken at approximately 250 cfs releases and a week later at approximately 500 cfs <br />releases. Average water temperature for all sites changed from 17 ,18oe at 500 cfs to 21.53oe at <br />250 cfs, for an increase of 25.3 %. Average dissolved oxygen changed very little from 7,80 rrtg/L <br />at 500 cfs to 7,61 mg/L at 250 cfs, for an decrease of 2.4 %. Average conductivity changed from <br />257 IlS/cm at 500 cfs to 3661lS/cm at 250 cfs, for an increase of 42.4 %. <br /> <br />River Segment 20.6.4.401 - (from Highway 64 bridge at Blanco, NM to confluence of the San <br />Juan and Animas Rivers at Farmington, NM) <br /> <br />The marginal coldwater fishery standard for ammonia was possibly exceeded. The detection <br />limit for the sample was 0.4 mgIL and the standard, based on temperature and pH at the time the <br />sample is collected, is approximately 0.35 mg/L (temperature and pH numbers were rounded up <br />to the table values which results in a conservative interpretation of the standard). <br /> <br />The water temperature at one site exceeded the marginal coldwater fishery standard, but was <br />below the warmwater fishery temperature standard. <br /> <br />The dissolved aluminum (169 ug/L) from the site upstream of the Highway 44 bridge in <br />Bloomfield, NM exceeded the chronic fishery standard (87 ug/L), but was less than the acute <br />fishery standard (750 ugIL). The results of dissolved aluminum samples upstream and <br />downstream were much less and the cause of the exceedence is not known, The laboratory has <br />been notified to check their records. <br /> <br />The fecal coliform results have been discussed previously. The fecal coliform sample at the <br />Highway 64 bridge at Blanco, NM is located on the boundary between river segments 20.6.4.401 <br />and 20,6.4.405. The fecal coliform standard for segment 20.6.4.401 is 400 colonies per 100 m1 <br />and the fecal coliform standard for river segment 20,6.4.405 is 200 colonies per 100m!. The <br />sample result was 240 coloniesllOO ml which for the river segment 20.6.4.405 is an exceedence <br />of the standard. Precipitation events did occur in the watershed area on the afternoons of July 9, <br />10, and 11, which contributed runoff and may have resulted in higher than normal results, <br /> <br />Page 9 of 15 <br />