The Kowmung begins where the Tuglow and the Hollanders come off the Boyd plateau, nine hundred metres up, and for its first sixteen kilometres it is a confined bedrock gorge dropping hard. The fall of the river below shows that first pitch clearly. Then the walls stay but the bed changes: from about the sixteen-kilometre mark to the Coxs the river runs on gravel between confined banks, with the occasional small flat where a side creek comes in, and the drop eases steadily until the last ten kilometres are close to level.

Above Morong Creek is the top: the Tuglow, the Hollanders and Morong Creek country, short, steep and cold, the stretch the trout classification is written for.

Morong Creek to the Coxs is the gorge, and it is most of the river. Cedar Ford, where the Gingra Trail comes down, is the one place the river is measured. Below it the walls open a little and the runs lengthen toward the junction.

The bank survey tells you what to pack. Satellite cover along the whole corridor reads as two-thirds dense forest and a third open woodland, with no cleared ground at all. The top ten kilometres are more open woodland, which is why the headwaters have a little more light in them, and the bottom of the gorge is the darkest water on the river, close to ninety per cent closed canopy in the last five kilometres. That shade is worth an hour of afternoon fishing on a day that would shut down the open tablelands to the west.

Wild, and mostly unrecorded. Nothing has been stocked here, and the only survey record bound to the river is a single river blackfish from 1910. The department classifies the headwaters as general trout water, which tells you what the authority expects to find there without counting anything. Brown trout are the fish the Blue Mountains gorges are known for, and a river this cold, shaded and remote is where they persist when the roadside water has been fished out. Treat the whole river as unproven rather than empty.

What they eat comes off the trees. In a closed-canopy gorge the terrestrials matter more than the hatches: beetles, ants, the odd cicada from late spring, dropping out of the overhang onto water that has not seen a fly all year. The gravel runs below Cedar Ford carry caddis and a nymph’s worth of larvae under every stone, and the evening riffle is the reliable hour.

This is a rain-fed gorge, not a snowmelt river, and the calendar below is a guide’s read of it rather than a gauge’s. After a decent fall in the country above Kanangra the river comes up fast, coloured and genuinely dangerous through the confined sections, and it takes a few dry days to drop back into something you can read from the bank. Check the forecast for the plateau, not for Sydney, and check the Cedar Ford readings on the gorge page before you commit to the walk.

From late spring to the first frosts the river is at its best: settled, clear, warm enough for the terrestrials, and cool in the shade on days the tablelands bake. Autumn is the quiet prime. Winter is cold, short and wet underfoot, and the headwaters are closed under the trout rules in any case.

Pack for a walk first and a river second. A four or five weight that breaks down small, a floating line, and a box that does one job well. The dry-dropper is the rig for the whole river: a dry you can see in broken light, a Stimulator or a Royal Wulff, with a tungsten Hare’s Ear or Pheasant Tail two feet under it. Fish every pocket once, as if it holds a fish, because in water nobody fishes it probably does, and move on. The first drift is the one that counts. In the evening runs an Elk Hair Caddis on its own. When the river is carrying colour after rain, a small Woolly Bugger swung through the deeper slots is the honest fly.

Casting room is the constraint. Roll casts, bow-and-arrow casts into pockets under the timber, a short leader you can control. The stretch pages say where the water opens up.

Everything is national park and almost all of it is on foot. Fire trails off Kanangra Walls Road and the Boyd plateau reach the headwaters, and the Ben Lomond trail touches the Hollanders near the top. Into the gorge the walks are long: the Gingra Trail off the Kanangra tops drops to the river at Cedar Ford, and the Uni Rover Trail comes in further up, both around fourteen kilometres from where you leave the car. Several named ways in, Roots Ridge, Bulga Ridge and Black Snake Bend among them, are bushwalkers’ routes rather than mapped tracks. The ways in are pinned further down this page; a pin is a route that reaches the river, not a promise about its condition today.

The lowest water runs toward WaterNSW’s special area around Sydney’s drinking-water storage, where the park rules give way to the water authority’s. Check with WaterNSW before you plan a trip that far down.

This is remote gorge country. Bedrock is slick, the walls pinch in, and a fall is a long way from a road and further from a signal. Carry what you would need to look after an injured person overnight, leave your plan with someone, and give yourself the daylight to walk back out. If the forecast is wet, do not go in.

NSW DPIRD classifies the Kowmung as a general trout water upstream of, and including, Morong Creek. That classification brings the NSW trout season and the general-trout-water bag and size limits with it, and it is stated on the headwater stretch. Below the Morong Creek junction the classification does not apply, and the ordinary NSW freshwater rules do.

The dates follow the long weekends and the numbers move. Check the current NSW freshwater synopsis and the trout closure notification before you go.