The lake when full covers some 1200 acres with depths down to 140 feet and holds 60 000 000m3 of water. The water is split into four sections, North, South and West Arms then the central basin. Each section is packed with features including weed, snags, ledges and plateaux. In addition to this, the water level can fluctuate by as much as 30 feet making the swims features change with the seasons.
In 1986 Kevin Ellis caught a 76lb monster Carp from a swim which is now known as Ellis point or Kevin Ellis. This put Lac de St Cassien well and truly on every Carp hunters map, every big name in Carp angling has spent time on Cassien including Steve Briggs, Max Cottis and of course Tim Paisley.
The West arm is closed from the 1st January to the end of June to allow the fish to spawn in the shallow water, which warms up quickly in the spring. The Carp take bread from the surface whilst gathered up to spawn, an impressive sight for eager anglers standing on the bridges above. As with every other lake anglers gather on the entrance/exit of the spawning grounds as prolific captures can be made as the fish move in and out.
The North Arm, home of the barrage, built in 1966, which forms the lake and was built for the production of hydroelectric energy, from which the water level is controlled is another out of bounds area, but this one is year round, the two swims that fish the area are very popular and consistently produce fish.
The South arm is where most anglers started their trips on Cassien, Gerrards hired boats etc back in the day but unfortunately closed some years ago. The South arm is popular through the summer months with swims such as Bivvy point, Electric point and the Bannana.
The Central basin is popular because of access, short boat rides to the Straight bank and probably the most accessible swim on the lake, the Bridge are all popular. The Bridge Plateaux can be fished from either end of the bridge and from the straight bank if your spools hold enough line!
The lake has some 50 odd recognised swims when the water level is at its peak, as the water level drops more bank space is available and you can fish from wherever you like. This makes for interesting fishing as lots of water can be covered by a single angler fishing 3 or 4 rods. As a pair of anglers fishing together, 3 rods each is the norm which enables you to cover various depths to find feeding areas, assuming you are actually on fish. The fish can move about the lake quite quickly and sometimes no amount of bait will hold them, on other occasions they can stay in an area for some time. Its fishing! There are no guarantees, you just have to read whats in front of you on the day.
Currently there is no night fishing on the lake, fishing is from 30 minutes prior to sunrise until 30 minutes after sunset.