Another scheme to lease the canal to the Neath and Brecon Railway for £9,000 per year in 1864 also foundered. The 1860s were a hard time for the canal, as the steel industry gradually replaced the iron industry, and ironworks contracted or closed. In 1871, the Company approached the Great Western Railway, and negotiated a price of £107,666 for the main Swansea Canal, and £40,000 for the Duke of Beaufort's Trewyddfa Canal. The sale took place on 31 January 1873. Rather than run it down, the Great Western Railway ran the canal well, and it remained profitable until 1895, when losses were first reported, though it recovered a little between 1898 and 1902. The tonnage of coal carried on the canal was very high, with 385,000 tons transported down the canal to Swansea in 1888 alone. The last commercial cargo carried on the Swansea Canal was in 1931, when coal was conveyed from Clydach to Swansea. Boats continued to operate on the canal after that date but only for maintenance work, with horse-drawn boats last recorded at Clydach in 1958. The canal was gradually abandoned, under the terms of a series of Acts of Parliament, starting with the Great Western Railway Acts of 1928 and 1931. The canal was nationalised in 1947 and became part of the British Transport Commission, whose Acts of 1949 and 1957 brought further closures. The remainder was closed under the terms of the British Transport Commission Act of 1962, when control of the canal passed to British Waterways, who remained responsible for the maintenance of the waterway and its structures until 2012, when they were superseded by the Canal and River Trust. In-filling of much of the canal has taken place in the past 50 years. The northern section was affected by the creation of the A4067 road around Ystradgynlais, while the southern section below Clydach had been infilled by 1982, as part of the work associated with the A4067 dual carriageway. Just five miles (8 km) of the canal remains in water, from Clydach to Pontardawe where it is now a popular trail and is part of route 43 of the National Cycle Network. The canal empties from an aqueduct into the Lower Clydach River at the point where it joins the River Tawe. A project is underway to dredge the canal and to remove the Japanese knotweed that grows extensively around the Swansea Valley. The canal is an important habitat for water birds and for eels.