20 years of state independence
The Lake Sarez is situated in the Pamir mountains of Tajikistan. It was created 90 years ago when a strong earthquake triggered a massive landslide that, in turn, became a huge dam along the Murghob River, now called the Usoi Dam.
Tajikistan 2011, "20 years of state independence" 
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The illustration of the souvenirsheet is showing the Sarez Lake.
The four stamps are showing:
Emomalii Rahmon, President of Tajikistan.
The Norak hydro power plant, the Sangtuda hydro power plant and the Rogun hydro power plant.