One of the larger rivers feeding into Sydney's Warragamba Dam - the city's main water supply. The Kowmung runs east through the southern Blue Mountains in New South Wales, Australia, passing through the Kanangra-Boyd national park in some of the most spectacular country on the Great Dividing Range.
The river is managed by the Sydney Water Board, and fishing, swimming, camping near the river and so forth are officially discouraged, even in the wilderness area, which is a long way upstream from the resouviour. However, the river is pristine, with water reliably safe to drink untreated inside the wilderness area, unlike many others that drain into the dam, and the Water Board tolerates hikers in the area.
One reason they can do so safely is that traffic down to the river will never be very high. It is in an extremely inaccessible location, about 3 hours drive from Sydney, 30km of which is along dirt roads. The roads only go to the end of the escarpment - the river is 3000 feet below. There are several trails down, none of which are well maintained, and all of which are extremely steep and rugged. The distance from the road to the river is not very far, but the walk takes four to five hours if you are in good shape and don't get lost on vague and unmarked trails.
Most trails go from the end of the Boyd plateau, accessible by dirt road from Oberon or Jenolan Caves. The first hour of all the trails heads across a high, flat plateau covered in low scrub and bare rock, with stunning views of Kanagra falls and Mt Cloudmaker as well as the surrounding valleys. Bird life is varied, with several species of cockatoos often seen, and lyrebirds heard singing from the valleys. The final thousand feet of the descent are populated by bell birds, with a very distinctive PING of a call.
The easiest approaches to the river are down Jingra Ridge, a long, meandering knifeback ridge covered in light dry eucalypt forest, with dramatic views to the valleys and mountains around. After a fairly long walk along the main ridge, trails plunge down several different small spurs to the river. The descent is extremely steep and quite slow, and your knees will not be happy by the bottom. And, of course, you always know that you're going to have to walk back up it, but I find that easier than the descent.
Vegetation on the side ridges is not lovely, either - mostly prickly mountain holly higher up, and stinging, cobweb filled bushes that make everyone sneeze lower down. On most side ridges there are some good cliffs and lookouts nearer to the bottom that make a good spot to stop and rest. My recommended trail, down Routes Ridge, goes past the top of Rainbow Bluff, a colourful limestone bluff above the river, covered in native rock orchids.
The river itself is mostly fairly shallow, flowing a few feet deep over pebbles, with rapids every hundred meters or so. The water is extremely clear and usually quite cold. The swimming is excellent nevertheless, particularly in a few large deep pools. The banks are usually rocky and jungly on one side, and broad with casuarina groves and grassy flats on the other. There is a good camping flat every few hundred yards down the banks. There is a kind of trail down the bank, but it is very vague. Walking up and down the river can become difficult in sections, with thick vegetation and frequent river crossings, but there are some lovely sections to walk and explore the pools and rapids of the river.
Note: Snakes are common. There is estimated to be one red-bellied black snake per 25m of river bank. Fortunately this species is fairly conspicuous, non-aggressive and not particularly venomous. In hot weather, they can often be seen swimming in the river, and should be watched for when swimming and rafting. There are also some large goannas that have been known to steal food from campsites.
The river is ideal for lilo rafting and trout fishing, and swimming for those with a high metabolism or a wetsuit. The environment is relaxing and isolated - it is unlikely to see more than one or two other parties in a weekend at the river. Overall, it is an excellent challenging hike to get to and the river is one of the most pure and beautiful in the world. Ideal for a two or three day trip, allowing 5 or 6 hours each way for the hike.