A source of stone was located near to Colt Crag reservoir, and a narrow gauge railway was built to transport it to the site. Clay was obtained from the site for the embankments, and bricks were made from book-leaf marl. This covered the area, and would subsequently be the cause of problems with the embankments. The company employed direct labour to build the reservoir, and some 60 navvies were engaged in this task. They used waggons and a hauling engine to move the material. Forster found that using manual labour was more cost-effective than using steam navvies. Work on the reservoir was suspended in early 1886 and early 1887, due to appalling weather conditions, and there were regular slippages in the embankments. The slope of the embankments was reduced, from 1 in 2 to 1 in 2.5, but a knowledge of soil mechanics was clearly lacking. Water was also a problem, and a spring which produced per day was discovered under one of the embankments in 1877. The reservoir started to fill in May 1889, although various tasks were still to be completed. In six years, some of earth had been moved, 33,000 waggons of stone had been transported along the railway, and 670,000 bricks had been manufactured and laid. The work had cost considerably more than the £40,000 that Forster had estimated. Labour along had cost £51,631, of which £23,557 was for extras, but Forster was not alone in miscalculating costs, as the company had experienced similar problems with projects supervised by an engineer as eminent at Bateman.