Despite the oyster grounds, Saltom Bay [on the Firth] signals another change in the coastline, now high, composed largely of slag and topped with industrial complexes, often derelict. The plants include the large chemical works of Albright & Wilson, based on Triassic anhydrite, its conveyors silhouetted against the skyline. This firm are permitted to discharge 500t of zinc, chromium, copper and nickel per year into the Irish Sea, the largest such discharge around the British coastline, but Greenpeace claimed that, in addition to illegally high quantities of these heavy metals there were also aluminium, beryllium, iron, manganese, silver, tin, boron, vanadium and titanium present, metals for which discharge is not permitted. Mussels here have the highest levels of cadmium ever recorded around the British coastline. Greenpeace brought the first private prosecution of a chemical company under the 1989 Water Act against them and blocked their outfall pipe for good measure, also calling for a judicial review of the NRA for failing to take action on known illegal discharges, Greenpeace subsequently attempting to withdraw from the judicial review but the NRA refusing unless Greenpeace paid all their legal costs.