The Dniester Hydropower Complex influenced the quality of water upstream, especially after accumulation lakes No. 1 and 2. The content of substances in suspension decreases suddenly in the Nistru downstream the complex and water becomes transparent. The accumulation lake is a kind of “trap” that prevents the suspensions from moving downstream. In the minor bed of the accumulation lake, a significant quantity of sediments, particles and slurry are deposited, shows a study commissioned by UNDP Moldova that is quoted by IPN.
The complex considerably reduced the content of heavy metals in the water of the Nistru. After going through the hydropower complex, the water contains less copper, zinc etc. and eventually other toxic organic compounds that can absorb particles and colloids. These pollutants are “caught” in the main accumulation lake and are deposited on the bottom without being pushed downstream.
The average values of the oxygen dissolved in water are practically the same as upstream and downstream the accumulation lake, but the oscillations of the oxygen concentrations upstream the barrage are visibly higher and this is incontestably due to the functioning of the hydropower complex.
It seems that under the influence of the hydropower station, the reaction of the environment (рН) changes. The slightly alkaline water typical of the Nistru, upstream the accumulation lake, becomes more neutral (is acidulated) when it then enter Moldova.
The Dniester Hydropower Complex exerts a visible influence on the technical regime of the river downstream as water for the turbines is collected from the deeper levels of the accumulation lake where the water has a lower temperature. Therefore, in the inferior section of the river between the floodgates, the temperature is higher than the normal level for the cold period of the year and is below the norm during the warm period.
The study was commissioned by UNDP Moldova and was developed by a team of independent experts at the request of the Ministry of the Environment, with financial support from Sweden.
