No abstract

The topic of the effect hydroelectric power stations on the environment, as in the first years of perestroika, appears rather often on the pages of newspapers, mainly in regions where the stations are located. However, whereas 5-8 years ago people ill-informed but moved by concern about the health of inhabitants of our country and of all mankind often wrote emotionally about environmental problems, today articles on this topic appear, as a rule, during preelection campaigns. Furthermore, during the difficult economic situation in the country individual structures have cooperative interests in taking possession of the property of power stations. In such a case hired professional journalists write the articles; a negative public opinion about the enterprises and the myth about the enormous ecological damage ostensibly inflicted by hydro developments due to defects of the designs and level of operation are created. Most often spoken about here are "putrid water" in the reservoir and global climate change.Is this so?The 20-year experience of operating the Sayano-Shushenskoe hydrostation and long-term observations and studies carried out by independent organizations, research institutes, and operating personnel of the hydrostation give the right to conclude that the hydrostation has not worsened the quality of water in the Yenisei River and has not lead to noticeable climate changes. Furthermore, processes of self-purification of water flowing in from the upper reaches of the Yenisei and its improvement due to dilution during spring filling of the reservoir with meltwater occur in the hydrostation's reservoir.Water Quality. Before the construction of the hydro development observations of water quality on the stretch of the Yenisei upstream of the hydro development were carried out only on the basis of hydrochemical indices. Since filling the reservoir (1978), observations and analysis of results are realized on the entire stretch of the river, from Kyzyl city to Sayanogorsk city. Hydrochemical, hydrobiological, and sanitary water-quality indices are examined. Since 1992 observations have been being carried out at two sites upstream of the reservoir (Kyzyl region), three sites on the reservoir, and two sites downstream. Under natural conditions the Yenisei water in the stretch under consideration belonged, with respect to its hydrochemical composition, to low-mineralized water of the bicarbonate class of the calcium group. Mineralization of Upper Yenisei water during freezeup is 120-220 mg/liter and in the remaining time of the year 30-165 kg/liter. The reaction of the water varies from weakly acid to weakly alkaline (pH 6.5-7.6).The gas regime of the Yenisei is relatively homogeneous. A high dissolved oxygen content is characteristic for the water.The mountain character of the river and low water temperatures determined the limited composition of biogenic elements. The content of nitrates in the winter was 0.7-1 mg/liter, and in the remaining time did not exceed 0.3 mg/liter; the concentrations of nitrites and phospho...