Klas August Widegren (sometimes wrongly Widigren), a Swedish civil engineer, was the son of Klas Emil Widegren and his wife Maria Charlotta Finlöf. He was a partner in the firm of consulting engineers K & H Widegren. (His partner was his brother Emil Henric Widegren). He visited South Africa in 1903-1904. During his stay he contributed some articles to the Agricultural Journal of the Cape of Good Hope. The most important of these was "Irrigation by means of artificial underground water" (1903-1904, Vol. 23-24, in 4 parts), in which he described the principles of ground water flow, underground storage capacity, artificial infiltration by conducting surface water to a basin dug in a storage layer, the economics of ground water utilisation, and water quality. A second article, "Water supply, drainage and epidemics" (1904, Vol. 24), dealt with the bacteria in water and its artificial storage in the ground. Further contributions by him were published in the latter half of the year (Vol. 25).
"Widegren brothers" sent a copy of the first of these articles to the Public Works Department of the Transvaal Colony, together with an article dealing with a new scheme of sewage and storm water drainage. The firm later published a pamphlet on The Widegren railroad (Stockholm, 1923). They were granted various patents, including one for a centrifugal friction clutch (1932).
Widegren was married to Emilia Maria Stjernstedt, with whom he had two children.