In conjunction with the construction work the Wrington Vale Light Railway was established connecting Blagdon with Congresbury on the Cheddar Valley Line and Yatton on the main Bristol to Exeter line. In addition to carrying construction materials for the reservoir and pumping station it also provided passenger services. Later the railway was used to bring coal for the pumps. Passenger traffic ceased in 1931 and the line to Blagdon closed completely in 1950. The lake is relatively shallow, with an average depth of and only at its deepest point near the dam at the west end of the lake. The eastern end is the shallowest where the River Yeo enters. It is a hard water area with high mineral content that is vulnerable to eutrophication in the summer, that can cause algal blooms, with transient water layers. As a result, a research programme has been established to observe and measure the limnology of the lake. When full it contains and supplies of water each year. Water can also be taken from its larger neighbour Chew Valley Lake to balance the supply. Dam The dam extends below ground to the solid rock underlying the valley. It was built of puddled clay with a central concrete core and faced with granite on the lake side. A diameter pipe through the dam leads to the pumping station while a larger one is used to remove silt collecting against the dam. A flow of water is maintained in the River Yeo through a compensation channel and an overflow weir and spillway take flood water downstream. Pumping station and Visitor Centre Blagdon Pumping Station and Visitor Centre includes science and environment exhibits and hands-on displays as well as a room dedicated to the charity WaterAid. One of the two steam-driven beam engines is still working occasionally. Outside this is space for picnics and a nature trail. When the lake first opened there were four Woolf compound rotative beam pumping engines, housed in two separate buildings. They were built by Glenfield & Kennedy of Kilmarnock between 1900 and 1905. The engine's beam is long and weighs 17 tons. The flywheel is in diameter and weighs 20 tons, having a crank throw of . Each beam engine had an output of at 17 rpm. The high-pressure cylinders, in diameter and with a stroke, were supplied by steam from horizontal Lancashire-type twin flue boilers with Green's economisers at