Glen Mervyn Dam (Collie)

Glen Mervyn Dam sits 18km south of Collie at Mumballup, off Collie-Preston Road, and it is the small, close, easy one of the South West dams. DPIRD names it among the most popular trout waters in WA, it is stocked annually alongside Logue Brook and Big Brook, and there is no trout season to work around here or anywhere else in the state. The two shores do different jobs: the eastern side is the day-use end with a picnic area, toilets and tables, while the western side is free bush camping under jarrah with shallow, sandy margins that suit families. There is a boat ramp, the Bibbulmun Track runs past, and the whole set-up is unfussy. Marron are here as well, and the rules for them are tighter than most visitors expect.

Light spin gear covers almost everything — small hard bodies and soft plastics for the trout, the same outfit worked slowly around structure for the redfin. Dawn, dusk and overcast days are the trout windows, and because the dam is open year-round, a winter morning is as legitimate here as a spring one. The shallow sandy margins on the western shore are the easiest water to put a kid on, while the eastern day-use side is where the toilets and tables are if the session turns into a picnic. A boat ramp gets a kayak, a paddleboard or a small boat on the water, with skiing prohibited in anything shallower than 1.5m. Marron are snare-only in season, and a drop net is illegal here.

Trout are the headline, and they ride on an annual stocking programme rather than a wild run. Trout are 300mm minimum and sit inside a mixed freshwater bag of four, counted together with freshwater cobbler. Redfin perch have no size limit and no bag limit, and as a declared pest DPIRD recommends they are not returned to the water and are humanely euthanased, with dead fish not left on the shore. Marron are 80mm minimum carapace, a daily bag of eight and a possession limit of 16, because Glen Mervyn is not a trophy water — the 90mm and bag of five people quote belong to Harvey Dam, Waroona Dam and the Hutt River.

Two rods or hand lines per person is the shore limit, and it is statutory rather than guide advice. The marron rules are the same trap as Logue Brook up the road: snare only, no drop nets, 80mm and a bag of eight, with no trophy-water uplift to soften it. Dogs are allowed on lead, and the fox baiting nearby is the reason the lead is not optional, because the baits are highly toxic to domestic animals.

Glen Mervyn is 18km south of Collie via Collie-Preston Road at Mumballup, in the Shire of Donnybrook-Balingup. The eastern shore is the serviced end, with a day-use picnic area, toilets and picnic tables, plus a boat ramp. The western shore carries the free bush camping under shaded jarrah and the shallow, sandy, family-friendly water, but the way in is a narrow unsealed track that is not suitable for towing a caravan, though a 4WD handles it — the free camping is a tent-and-swag proposition, not a van one. Camp and cooking fires are not permitted anywhere here, so a gas stove is the only way to get a cup of tea out of the morning. No accessible facilities are listed for the dam, dogs are allowed on lead, and it is worth confirming current camping and day-use charges before you go.

No tide and no swell inland, so the variables are water level, wind across the open water and light. Trout are a cool-water, low-light fish — overcast days and the hours either side of dawn and dusk — and because the fishery is open all year here, winter is genuinely on the table rather than a consolation prize. Summer heat pushes the trout deep and hands the day to the redfin. The shallow, sandy margins along the western shore are the first water to warm; the eastern day-use side is the one with the facilities. Spring, after the annual stocking, is the strongest window of the year.

Fox baiting occurs near the dam and the baits are highly toxic to domestic animals, so if the dog comes it stays on the lead and out of the scrub. The track down to the western shore is narrow and unsealed and will not take a caravan; a 4WD manages it, and a loaded trailer is asking for a long reverse. Ski boats share the open water outside the shallows, with skiing prohibited in anything under 1.5m, so a kayak is better kept to the margins. Campfires are prohibited outright, which matters more than usual in jarrah forest in February. There is no patrol here and no reliable information on mobile coverage, so tell someone where you are going and when you expect to be back.

Yes. A South-West Freshwater Angling Licence from DPIRD covers all freshwater angling south of 29°S and above tidal influence, which includes Glen Mervyn Dam, and anglers under 16 are exempt. Marron require a separate recreational marron licence on top of that one.

No. Glen Mervyn is a snare-only water under the Fish Resources Management Regulations, so a single marron pole snare is the only legal method here. Within 50m of the water the only gear you may possess is that pole snare, rods and lines and a landing net, which puts drop nets and scoop nets out of bounds at the water's edge whether the season is open or not. The season runs from 12 noon on 8 January to 12 noon on 5 February each year.

Yes, and so is every other trout water in the state, because WA has no trout season anywhere. Trout are 300mm minimum and sit inside a mixed freshwater bag of four counted with freshwater cobbler, and the dam is stocked annually, so spring after the release is the strongest stretch.

Yes, free bush camping is available on the western shore under shaded jarrah, but the way in is a narrow unsealed track that will not take a towed caravan, so it suits tents, swags and 4WD setups. Camp and cooking fires are not permitted at all, so bring a gas stove. The eastern shore is the day-use side, with a picnic area, toilets, picnic tables and a boat ramp.

Yes, on lead. The serious catch is that fox baiting occurs nearby and the baits are highly toxic to domestic animals, so keep the dog leashed and out of the surrounding bush rather than letting it range while you fish.