Laserfiche WebLink
<br />. <br /> <br />. <br /> <br />. <br /> <br />r"' <br />l\) <br />A <br />o <br /> <br />SUMMARY <br /> <br />The Quality of Water Progress Report for the Colorado River Basin <br />is prepared and updated every 2 years to summarize the status of water <br />quality in the Colorado River Basin. Al though several water quality <br />parameters are reviewed, salinity is by far the most serious and is <br />allotted a major portion of this report. The report summarizes the <br />past, present, and future projected salinities at various stations in <br />the basin; discusses the causes of salinity; summarizes the development <br />of the water supply of the basin and its impact on salinity; reviews the <br />salinity control program; and summarizes special studies related to <br />water quality in the basin. <br /> <br />Extremely high flows in the Colorado River, two to three times nor- <br />mal, have reduced salinity to its lowest level in 30 years. All of the <br />main stem reservoirs were flushed by these high flows and now have in <br />storage water with unusually low salinities. According to the latest <br />salinity projections, the numeric criteria at Imperial Dam will be satis- <br />fied until 1993 by the salinity control units already in operation. <br />Development in the basin, which reduces the flow of the river and its <br />ability to dilute salinity, is projected to increase water depletions <br />from 9.6 million acre-feet per year in 1983 to 12.8 million acre-feet <br />per year by 2010. To maintain the lllJlDeric salinity criteria of 879 <br />milligrams per liter (mg/L) at Imperial Dam, a 1.5-million-ton salt load <br />reduction will be necessary to compensate for the development of this <br />water. <br /> <br />Nutrient loading to the main stem reservoirs is becoming a problem <br />as development and its associated pollution increase. Increases in <br />phosphorus and nitrogen compounds which are essential to the growth of <br />algae, the base of the food chain in reservoirs, are causing some por- <br />tions of the reservoirs to become eutrophic (overly productive). <br />Eutrophication of reservoirs can impair municipal, industrial, and <br />recreational uses by causing taste and odor problems, creating toxins, <br />and reducing the dissolved oxygen available for fish. While nutrients <br />in some reservoirs are causing them to become eutrophic, reservoirs <br />further downstream are becoming nutrient poor due to the trapping of <br />nutrients in the upstream reservoirs. This has the effect of reduc- <br />ing the productivity of the fisheries by limiting their food supply. <br />Studies are described which help define and resolve some of these <br />problems in the Colorado River Basin. <br />