Loch Long
Loch Long is a body of water in the council area of Argyll and Bute, Scotland. The sea loch extends from the Firth of Clyde at its southwestern end, to the Arrochar Alps at the head of the loch. It measures approximately in length, with a width of between. The loch also has an arm, Loch Goil, on its western side.
Loch Long forms part of the coast of the Cowal Peninsula, and forms the entire western coastline of the Rosneath Peninsula.
Loch Long was historically the boundary between Argyll and Dunbartonshire; however, boundary redrawing in 1996 meant that it moved wholly within the council area of Argyll and Bute.
Villages on Loch Long
Villages and hamlets on the loch include.Royal Navy
On the eastern shore of the Loch is the Royal Navy's Coulport Armament depot, with the Glen Mallan jetty, both part of Defence Munitions Glen Douglas. Part of the extensive Royal Navy's, His Majesty's Naval Base Clyde.Historic
In Arrochar, the Royal Naval Torpedo Testing Station and Range was established on the Loch in 1912, in connection with the Clyde Torpedo Works on Eldon Street, Greenock, established in 1910. Both sites are now closed.Finnart Oil Terminal
The Finnart Oil Terminal is located on the eastern shore of the loch, linked to the Grangemouth Refinery via a pipeline.In September 2024, it was announced that the oil terminal is scheduled for closure.
Environment and concerns
Loch Long has a long term issue with rubbish collecting at the head of the loch. Rubbish mainly washed down water courses from the Glasgow area.From about 2010 to 2025, due to inadequate maintenance of 1,500 water pipes at RNAD Coulport, some tritium used periodically to replenish Trident nuclear weapons leaked into Loch Long, constituting a low level of radioactive pollution. Analysis by Scottish Environment Protection Agency suggested that up to half of the pipeline components at the base were beyond their design life.