Its main inflow, at the northern end, is the River Cur, and its main outflow, at the southern end, is the River Eachaig, which meanders somewhat within the confines of the broad strath before flowing into the head of Holy Loch, about 5 km further south.

The Loch Eck water treatment works opened in 1977, upgraded in 2012 by Scottish Water, which supplies the freshwater to much of the southeast of Cowal, including Dunoon.

[11][12] In July 2013, two dogs died due to algal bloom present in the loch.

Warnings were then posted advising that people and animals should avoid contact with the water.

[15] The actress Emma Thompson owns a house on the shore of the loch.