The Kowmung River rises to the south and south-west of Jenolan Caves. Its two source tributaries are the Hollander's River which drains the high ground two miles to the south of Jenolan, and the Tuglow River which has its source on the Main Divide at Shooters Hill. The junction of these two streams is the official beginning of the Kowmung River.

Almost the first (top) half of the Kowmung shapes a huge hook around the Kanangra-Boyd National Park, before it continues in a generally north-east direction to its junction with Cox's River. The western arm of the 'hook' forms the Upper Kowmung Gorge, and the plateaus on both sides of the river rise to over 4000 feet. The fierce nature of the terrain means that this part of the river jealously guards its secrets; the granite walls drop steeply into the river, progression is confined to the river where long pools which must be swum arc separated by rapids, waterfalls and boulder chokes. Parties who 'do' the floor of the Upper Kowmung arc rare, and about three days are needed to complete the classic canyon section from Morong Falls to Lannigan's Creek. The other method is not a cosy alternative; the compulsory swims and waterfalls can only be avoided by negotiating the dizzy sidelings on the western side of the gorge. (Jim Barrett).

This is the story of development of the Kowmung Valley before construction of the Warragamba Dam.