Artificial lake „Siemianówka” is one of the biggest artificial lakes in Poland. There arose necessity of total or partial displacement of more than 200 farmsteads from eight villages. Five of them were entirely liquidated (Garbary, Boltryki, Louka, Boudy) – they were flooded. Largeness of the area of the lake Siemianouvka is seen from the observation point on the dam (the front barrier) in the vicinities of the villages Bondary and Rybaki. An interesting view stretches from the bridge by the railway which is on the embankment dividing the lake into two parts. The area of the lake equals 3250 ha, the maximum depth – 7 m. The maximum length of the lake comes to 13,5 km, but the width 1,4 km. This basin had to serve different functions among other to regulate water economy, be a body of drinking water for the Bialystok agglomeration and create conditions for development of recreational-tourist infrastructure. Retention reservoir is a dwelling place of a lot of species of rare birds. It was artificially stocked with fry and now is quite an attractive place for anglers . The area around the reservoir is hardly developed, banks are often overgrown by luxuriant flora. At the lake there are two beaches with bathing places (in villages Bondary and Rybaki).