Laserfiche WebLink
<br />OJZ284 <br /> <br />frequency, spatial resolution of measurements, and changes in instrumentation, four distinct <br /> <br />phases of monitoring activity can be identified (Table II-I). <br /> <br />From 1965 to 197 I, monthly sampling of the Glim Canyon Dam forebay and quarterly <br /> <br />, surveys of the entire reservoir for temperature and salinity characterized,monitoring..activity.-. .__ _ ___ . <br /> <br />Measurements and samples were collected at 50-foot depth intervals at seven locations on the <br /> <br />reservoir. <br /> <br />g'~ <br /> <br />From 1972 to 1981, the frequency of lake-wide surveys was increased to a monthly basis. <br /> <br /> <br />From 1982 to 1990, sampling activity steadily declined to single lake-wide surveys in 1988 <br /> <br /> <br />and 1989. Despite the decline in sampling frequency, advances in instrumentation allowed the <br /> <br />collection of higher quality data at finer depth resolution. Continuous monitoring of temperature <br /> <br /> <br />and salinity of the tailwater was initiated during this period. <br /> <br /> <br />In 1990, concurrent with the implementation of GCES Phase II studies, Reclamation's Lake <br /> <br /> <br />Powell monitoring program was restructured. Monitoring frequency was returned to a level of <br /> <br /> <br />monthly forebay surveys and quarterly lake-wide surveys. During the Phase II Research Flow <br /> <br /> <br />period from 1990 to 1991, the monthly forebay surveys were conducted by the US Geological <br /> <br /> <br />Survey (Hart and Sherman, 1995)). This restructuring resulted in a redistribution of resources to <br /> <br />allow the collection of data at a finer spatial resolution while reducing the number of samples <br /> <br /> <br />collected for chemical analysis. Sampling for nutrient chemistry and biological conditions was <br /> <br /> <br />also initiated. The objective of this phase of monitoring activity was to establish a program of <br /> <br /> <br />basic data collection that would balance cost with the ability to track changes in reservoir and <br /> <br /> <br />release water quality and evaluate the effects of Glen Canyon Dam operation on these resources <br /> <br />Various agencies and institutions during Lake Powell's history have conducted other work. <br /> <br />Studies have been conducted by educational consortiums and federal and state agencies on <br /> <br />03/06/98 <br /> <br />DRAFT <br /> <br />Page 8 of 62 <br />