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<br />r <br />r~ <br /> <br />~,: <br /> <br />megawatts as the target for the river downramp limit of 1,500 cfs and 160 megawatts as <br />the target for the river upramp limit of 4,000 cfs. Generation schedules supplied by <br />Western often reflect the maximum downramp or upramp limits from hour to hour. If a <br />request for generation at Glen Canyon provides for an upramp of 160 megawatts in the <br />next hour and the control center operators need to bring another unit on line, water release <br />could exceed the upramp river constraint by 155 cfs for a short period of time. 155 cfs is <br />3.8% of the upramp river limit. <br /> <br />~.J;\ <br />usbdwapa ^ <br />~\t tI. <br />'f l . <br />vJ ~tP~ I <br />'-\!I~ 'jJ <br /> <br />Lee Ferry Gage: Another report of flow conditions out of Glen Canyon Dam is the <br />USGS gage at Lee Ferry, approximately 15 miles downstream. This is the official point <br />of measurement for water deliveries to the lower basin states. Gages also report with <br />error. The USGS gage at Lee Ferry is rated as "excellent". An excellent rating is given to <br />a gage if it reports within an error range of ~5%. The gaging station reports flow every 15 <br />minutes. <br /> <br />, <br />" <br /> <br />I-v"! <br />~~: <br />l..l <br />~:;;., <br /> <br />".; <br />'., <br />:;'1 <br /> <br />:. .~ <br /> <br />VI. Environmental Effects to Date <br /> <br />Additional data may be necessary to quantify impacts, if any, of small deviations resulting from <br />regulation. There is, however, some evidence that the environmental impact of regulation does <br />not differ from those described for the preferred alternative in the EIS. In an article published in <br />"Rivers", an analysis was made of the effects of regulation and other electrical reliability criteria <br />on the river ecology of the Lower Flathead River in Montana. The authors concluded that " Very <br />sma/lfluctuations around the hourly mean discharge [resulting from operations of the Kerr Dam <br />to meet electrical reliability criteria] have little, if any, quantifiable effect on the downstream <br />aquatic environment because short-term electrical excursions resulting inflow fluctuations of <br />short duration are quickly dissipated by river hydraulic processes. 5" This conclusion seems to be <br />borne out through analysis of the data regarding flows below Glen Canyon Dam. In June, 1998, <br />while the downramp, as recorded by SCADA, exceeded 1,500 cfs about 4% of the time, there is <br />no exceedence at the Lee Ferry gage. River attenuation between the dam and Lee Ferry reduces <br />fluctuations. In fact the highest down ramp recorded at the Lee Ferry gage during this month was <br />~,2 ~: :;:, ~:;::e :~: ~.~~ !:~itations on the downr:ur:p were established in order to reduce the <br />degradation of beaches in the Marble Canyon area (below Lee Ferry), one could use the <br />conclusion from the "Rivers" article as a working hypothesis for any further investigations in this <br />area. <br /> <br />(; <br /> <br />: .1 <br />, <br />r-o' <br /> <br />f;.:-- <br /> <br />~{~ <br />, . <br /> <br />"'" ~. ! <br /> <br />t~ <br />~';>- <br />:1..) <br /> <br />~ Jourdonnais, Jon H, & Hauer, Richard F., Electrical Frequency Control and its Effects <br />on Flow and River Ecology in the Lower Flathead River, Montana, Rivers, Studies in the <br />Science Environmental Policy and Law ofInstream Flow, Vol 4, Num. 2, April 1993, S.E.L. & <br />Associates <br /> <br />7 <br />