Drumacrittin Lough ASSI

Physiographical interest of this largely spring-fed lough and the small satellite lough to the north, Black Lough, is related to the presence of calcium carbonate deposits, or marl, which are precipitated out of the calcium-rich water to produce a marl lake. Drumacrittin is one of the best examples of this lake type in Northern Ireland and is notable for its clear, clean water and very low phytoplankton productivity.

The lough exhibits the natural succession from open water to terrestrial vegetation and includes a number of unusual plant communities, in addition to several rare plant species.

The aquatic vegetation is of particular importance, asit represents the most extensive submerge growth of Stoneworts (Charophytes) found in Northern Ireland including bristly stonewort Chara hispida and the regionally rare rugged stonewort Charophytes rudis.