During 1999, the UK’s largest "run-of river" hydro-electric plant was built at Beeston Rylands Weir. At the maximum consented flow rate, 60 m3/s of water passes through the pair of turbines. Upstream of the weir and during the salmon migratory period, the plant utilises a bio-acoustic fish-fence—a bubble curtain in which the bubbles contain a sound that the fish do not like. This fish fence steers migrating fish away from the fast-flowing turbine intakes and into the fish ladder, by which the fish can safely negotiate the weir. The power generated supplies enough electricity (1.5 MW – 1.66 MW) for two thousand homes, a total of 5.26 GWh annually.