Facilities at Giant's Grave improved, and included jetties to enable ships' ballast to be landed and dumped, rather than being thrown overboard. This latter approach had caused problems at Newport for the Monmouthshire and Brecon Canal, where ballast had been thrown into the river, and at Cardiff for the Glamorganshire Canal, where it had been thrown into the canal basin. Efforts were also made to improve the facilities at Neath. From 1818, a Harbour Board was established, and banks of copper slag, marked with buoys, were used to confine the channel. This enabled ships of over 300 tons to reach Neath quays on spring tides, although on neap tides Giant's Grave still had to be used. From 1824, when the connection to the Tennant Canal opened, much of the trade crossed the river and passed down the western bank to the port of Swansea.