According to official figures, during the construction of Belomor, the White Sea Canal, 2.24% of the prisoners in the BelBaltlag camp complex died in 1931 (1,438 persons), 2.03% died in 1932 (2,010 persons) and in 1933, due to famine in the USSR and the rapidly approaching deadline to finish the project, 10.56% of the prison workforce died (8,870 persons).

Seventy years later, in August 2003, Yury DMITRIEV discovered a large burial ground of BelBaltlag prisoners near the 8th lock on the White Sea Canal. The following year volunteers under his direction cleared the area and found more than 800 graves.
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After work on the canal was completed on 4 August 1933, over twelve thousand prisoners were released and terms of imprisonment in the camps were reduced for a further 59,516 inmates of the White Sea-Baltic camp complex, or Belbaltlag as it was known for short.
Six major OGPU officials were decorated with the Order of Lenin for their management of the construction work (G.G. Yagoda, M.D. Berman, I.L. Kogan, Ya.D. Rappaport, S.G. Firin and N.A. Frenkel), as were two amnestied engineers, Zhuk and Verzhbitsky.
Excerpt from Russian Wikipedia

The Canal’s 19 locks, from Lake Onega (W) to the White Sea (E)
See also Anna Yarovaya, “The Badgers’ Hill graveyard”,
7×7 – Horizontal Russia, 29 September 2017 [R]
The Stalin Canal
In May 1933 the head of OGPU, Genrikh Yagoda, reported to Stalin about the project. Construction was completed on 20 June 1933, and the canal was named in honour of the Soviet leader. On 25 June it opened for water-borne traffic and the steamboat “Chekist” travelled along the canal from one end to the other.
In July 1933 Stalin, Kliment Voroshilov and Sergei Kirov — People’s Commissar for Military and Naval Affairs and Party boss of the Leningrad Region, respectively — travelled along the new man-made waterway in a cruiser. Privately, it was said, Stalin was dissatisfied with the canal: it was narrow and no more than 3.65 metres deep at the time.

The White Sea Canal (Pyotr Belov, 1985)
Above is depicted the “White Sea Canal” brand of cheap Soviet papirosy (cigarettes with a cardboard filter), favoured by Yury DMITRIEV. The words “The USSR Ministry of Health warns: smoking is bad for your health” can just be made out, upside down, to the right of the rent in the top of the packet.