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<br />002283 <br /> <br />100 feet below the penstock withdrawal zone and weakened the strong chemical stratification that <br /> <br />had previously built up below that level. <br /> <br />In February 1997, increases in Upper Colorado River Basin runoff forecasts prompted an <br /> <br />increase in Glen Canyon Dam releases that were sustained at levels above 20,000 cfs for the <br /> <br />remainder of the summer months. This represented a different operational pattern to handle the <br /> <br />forecasted runoff than in 1983, which experienced similar hydrologic conditions. <br /> <br />B. Reclamation Monitoring Program <br /> <br />Table 1. Major Features of Monitoring Program Phases <br /> <br /> Phase I Phase 2 Phase 3 Phase 4 <br /> 1965-1971 1972-1981 1982-1990 1990- Present <br />Frequency: <br />forebay monthly monthly quarterly to yearly monthly <br />reservoir quarterly monthly quarterly <br />number of <br />stations 8 8 8-10 15-20 <br />Parameters Temp. Temp. Multiprobe Multiprobe profiling <br /> DO (Winkler) DO (Meter) profiling (T, SC, with datalogger <br /> DO, pH, ORP) <br />chemistry Major Ions Major Ions Major Ions Major Ions <br /> (Shipboard Nutrients <br /> processing) <br />sampling 50 ft 50 ft 50 ft Variable <br />interval <br />biological none none qualitative chlorophyll <br />sampling plankton phytoplankton <br /> zooplankton <br />inflow none none selected sites selected sites <br />monitoring <br />tailwater none none below dam below dam <br />monitoring T,SC Lees Ferry <br /> T, SC, DO <br /> <br />The Bureau of Reclamation initiated a water quality monitoring program on Lake PoweIl in <br /> <br />1964 to gather information on initial water quality conditions and to observe changes as the <br /> <br />reservoir fiIled and matured. This program has continued to the present. Based on sampling <br />03/06/98 DRAFT Page 7 of 62 <br />