South Branch Raritan River Fishing Guides and Conditions, New Jersey

About the South Branch Raritan River

The South Branch of the Raritan drains the New Jersey Highlands, running south from Budd Lake through Long Valley and Califon to High Bridge, then east through Clinton and Flemington to meet the North Branch near Branchburg. The reach that gives the river its reputation is the three-mile run through Ken Lockwood Gorge below High Bridge, where the river drops through a wooded ravine on an old rail bed, boulder to boulder, with almost no development on either bank. It is the closest thing New Jersey has to a mountain trout stream and it is fished accordingly.

The gorge is managed as a year-round catch-and-release fly-fishing-only area, which keeps fish in the river and makes holdover browns a realistic expectation rather than a happy accident. New Jersey stocks the river heavily in spring and again in fall, wild brook trout come out of the cold feeder streams above Califon, and the trout population below the gorge thins as the water warms toward Clinton, where smallmouth bass become the practical target. The hatches are respectable – blue-winged olives, sulphurs, and a good caddis population – but the river fishes as well on nymphs and streamers as it does on dries.

Access is generous by New Jersey standards. The gorge road is a one-lane gravel track along the river with parking pull-offs the entire way, and Ken Lockwood Gorge and Columbia Trail together give continuous walk-in access from High Bridge upstream toward Califon. The tradeoff is pressure: this is the most heavily fished trout water in the state, and stocking days draw crowds. The High Bridge gauge reads discharge and stage and is the reference for whether the gorge is wadeable; the station’s temperature series has not reported since 2021.

Access

Ken Lockwood Gorge Wildlife Management Area - the gravel gorge road below High Bridge with pull-off parking along its length, and the centre of the fishery.
High Bridge - the downstream end of the gorge, reached from Main Street, and the closest access to the gauge.
Califon - upstream access to smaller, colder water where wild brook trout appear in the feeder streams.
Columbia Trail, the rail trail on the old High Bridge line, gives walk-in access parallel to the river for miles.
Clinton and the reach below the Spruce Run confluence hold smallmouth bass through the summer once trout water warms.
The gorge road is one lane, unpaved, and closed seasonally after storms; check the county park status before driving in.
The catch-and-release fly-fishing-only boundaries in the gorge are posted at both ends and enforced.

Seasons

Spring: stocking plus snowmelt make March through May the busiest and most productive stretch of the year, with high, cold, pushy water in the gorge.
Summer: the gorge stays fishable longer than the open reaches because of its shade and gradient, but by late July the water below Clinton is smallmouth water rather than trout water.
Fall: prime. Fall stocking, cooling temperatures, and holdover browns in the gorge feeding hard before winter.
Winter: the catch-and-release section stays open all year and fishes well on mild days. Ice in the gorge makes wading genuinely risky in a cold snap.