The Lakes

Central to Killarney National Park are the world famous Lakes of Killarney, which make up almost a quarter of the Park's area. The three lakes are known as the Upper Lake, Muckross Lake (Middle Lake) and Lough Leane (Lower Lake), and are joined at the 'meeting of the waters', a popular area for visitors to the Park. It is here that the Old Weir Bridge (thought to be over 400 years old) can also be seen.From the meeting of the waters a narrow channel known as the Long Range leads to the Upper Lake, which is the smallest of the lakes but set in the most spectacular location, in the heart of the rugged mountain scenery of the upper Killarney Valley/Black Valley area. The sandstone and blanket bog of the catchment area means that the Upper and Middle Lakes are slightly acidic and low in nutrients (oligotrophic). A fast run-off in the mountainous catchment also means that in heavy rain the level of the entire Upper Lake can sometimes rise by up to a metre in a matter of a few hours.

Muckross Lake is the deepest of the lakes with a maximum depth of approximately 75 metres (250 feet) close to where the steeply sloping face of Torc Mountain enters the lake. Both Muckross Lake and Lough Leane lie astride the sandstone/limestone boundary, and the presence of limestone means that both of these lakes are slightly richer in natural nutrients than the Upper Lake. At lake level, there are many caves in the limestone which are formed by the dissolution effect of acidic waters on the exposed rock, especially when combined with wave action. Nowhere are these caves more marked than on the northern shore of Muckross Lake.

Lough Leane is by far the largest of the three lakes, at approximately 19km², and is also the richest in nutrients. Organic pollution (particularly phosphates from domestic and agricultural sources) entering Lough Leane has led to a partial eutrophication of the lake and several well publicised algal blooms have occurred in recent times. Although they can look unsightly, these blooms do not, as yet, appear to have had a severe effect on the natural life of the lake. If enrichment continues unabated however, the lake ecosystem may be altered to the extent that the character of the lake will permanently change, and a broadly-based review of land use within the entire catchment is therefore currently in progress in an effort to address the issue. A community-based initiative aimed at minimising the use of domestic and agricultural phosphates is also currently in progress, and it is hoped that a sustained effort will improve the water quality in years to come.

There are many Brown Trout in the lakes, in addition to an annual run of Salmon. Unusual fish species include the Arctic Char (usually found much further north, and thought to be a relict species left behind in Killarney after the last ice age) and the Killarney Shad (a land locked form of the Thwaite Shad unique to the Lakes of Killarney). The discovery of a small number of Roach a number of years ago, a potentially explosive breeder that was presumably introduced accidentally by visiting anglers, led to fears that the trout may be displaced in some parts of the lake however this fear has not materialised and Roach have not been recorded for several years.

Several different tours by boat are available for visitors to the Park, from short trips to Inisfallen Island, to the full passage of the lake system from Lough Leane to the top of the Upper Lake.