Appearing before South Lakeland magistrates on 20 April, the company pleaded guilty to causing polluting matter to enter controlled waters, contrary to section 85(1) of the Water Resources Act 1991. It was also ordered to pay £995 costs.
On 28 November last year, members of the public told the Environment Agency that the river Gowan was discoloured at Ings and Staveley.
Officers found a large hole in the car park of the Watermill Inn, Ings. The hole had been dug by Hutchinson Drainage to install new sewage treatment facilities for the inn.
The hole had filled with groundwater during the work and the foreman had decided to pump the water into the river to save money, in spite of the environmental implications. The company describes itself as "pollution control specialists" on its website.
Water samples taken from the river revealed a high suspended solids content. The Agency said that the pollution threatened wildlife habitats and fish and noted that the river is a a Special Area of Conservation as well as a Site of Special Scientific Interest, and supports rare native crayfish.