Old Yakushkina, district of St. Sergius, Samara region.
115 km von Samara. M5 E30 to Sergievsk 110 km, turn right to Staroe Yakushkino, at the begin of the town turn left, single lane dirt road, signposted, 2.5 km.
|L=36 m, W=32 m, VR=23 m, T=8 °C.
|Goluboye Ozero Samara, Samara Oblast, Russia 446556.
|As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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|mentioned as a natural sulfur spring by a russian scholar.
|collapse at the floor of the lake increases the depth by 10 m.
Голубое озеро (Goluboye Ozero, Blue Lake) is one of numerous blue lakes in Russia. Like all the others, it is actually a description not a real name, which is the reason why we add the location to the name, just to keep them apart. And like most other blue lakes, the blue colour is karst related. The spring is a resurgence, an opening where the water emerges from a cave deep below, and as the spring is a deep pot and the water full of limestone or gypsum, it gets a unique blue colour, hence the name. In general such lakes are circular, because they are the result.
The spring was first mentioned in the 19th century by a russian scholar who travelled through this area. In his report he stated that the water was full of sulfur and thus not usable as drinking water "neither for people nor for cattle". Gypsum karst develops rather fast, the gypsum is easily dissolved by water, and so the sprin in its current form is the result of a collapse in 2013. The cave at the bottom of the pot collapsed and the lake became 10 m deeper. Also, a waterfilled gypsum cave opened by this collapse which is the source of the water. It has been explored by Samara cave divers to a depth of 34 meters. But cave diving is very dangerous and this cave has so far not been explored completely. On the other hand the spring is now and then visited by excursions of caving clubs from Samara. It's an interesting day trip. But those divers never enter the cave because it is too dangerous.
This blue lake is a karst spring connected to a submerged cave system which drains the nearby gypsum karst area. The plateau between the spring and the nearby town Samsonovka is used for agriculture, and there are numerous dolines in the fields which can be easily seen. The gypsum is CaSO4, in other words it contains sulfur, which causes an unpleasant smell of rotten eggs of the water. It is not very strong and rather common for many springs, though in general mostly for thermal springs. Being karst water the spring has the same temperature throughout the year and thus does not freeze in winter.
The blue colour is a property of the water which contains a high amount of dissolved gypsum, so it filters all colours from the sunlight except blue. As a result the blue is quite intensive when the sun shines on the spring, during bad or cloudy weather it cannot be seen. It is also a result of the absence of algae in the water, or any other life for that, which results from its origin in a cave. The locals noticed this fact and call it sometimes the dead lake. They also believe that the water cures any kind of disease, obviously its necessary to swim in the pool for that, and there is even a small jetty for that. Nevertheless, with only 8 °C that's a quite uncomfortable swim and not for anyone. The locals only take dips, when the water feels unbearable after a few dozen seconds they get out.
In the 1960 crude oil was pumped in the area. The oil and gas production department of Sergievsk-Neft built a water pipeline to pump water from the spring, which they needed in the process. It seems the oil was soon exhausted and the company shut down, the iron pipes were removed for scrap metal, but a few pieces are still there, one creates a sort of artificial waterfall.
Nearby are two more sulfur rich springs, the huge, shallow, and much warmer мелкое озеро (melkoye ozero, shallow lake), also called black lake by the locals, and the Little Blue Lake. All the spring water flows after a few hundred meters into the small river Reka Shungut.