The ice holds on up here until late May. When it goes, a broad shoal in the middle of the lake lies only a few feet under the surface, weed greening up on it, and trout that spent the winter in the deep corners come up onto it to eat. Big O.K. is a fly-only lake high in the hills west of the Highland Valley, with the Thompson canyon at Spences Bridge somewhere below to the west, and it has a name for growing heavy rainbows.
It is a small water, held back by an earthen dam at its southwest end, and it comes in three parts. In the middle and along the east shore is a sunken island, a flat of shallow weed. Two deeper pockets sit in the northwest and northeast corners. The deepest water lies at the south end, against the dam.
The sunken island is where you start. It is shallow enough for weed and shrimp, and when chironomids, mayflies or sedges are coming off, trout spread across it and feed in water you can almost read from the boat. Anchor along its edges, where the flat falls away, and you cover fish moving up from deeper water to eat.
The corner pockets are the find on a bright, still afternoon, when the shoal goes quiet. Fish slide back into the darker water off the northwest and northeast ends, close to the campsite on the north shore, and a slow fly fished deep along the drop-off picks them up when the flat gives you nothing.
The south end, along the dam, is the deep water and the one to leave until you know the lake. Fish hold there in the warm weeks and you fish it slowly and deep.
Spring after the ice and the cool weeks of autumn are when the lake is at its best. It is fly-only water, so leave the spinning rod in the truck.
If the shoal at Big O.K. is quiet, Calling Lake is a few minutes down the same road, shallower, and a different lake to read.
Fish in this water
Each fish is rated by its strongest evidence. A rating says how sure we are a fish is here, not how many there are, whether it is worth fishing for or whether you may keep it.
Likely
Older records here, recent stocking, a local guide or fly shop, a guide listing, or recent records on connected water nearby.
How to fish it
Anchor a small boat or pontoon on the edge of the sunken island, bow and stern if the wind allows, so you can fish the flat and the drop with the same cast. Start with a chironomid pupa in size 12 to 16 under an indicator, set so the fly hangs just above the weed. If nothing happens in twenty minutes, change depth before you change fly: lift it a foot, then drop it toward the bottom. Still nothing, swap the chironomid for a scud and retrieve it slowly through the weed tops in short pulls.
When sedges are hatching in the evening, change to a sedge pupa fished on a slow, steady pull toward the shoreline weed, and then to a dry if fish start slashing at the surface. On a bright afternoon move to the corner pockets and fish a leech or a mayfly nymph slowly along the drop on a sinking line. You fish one fly at a time here; change the pattern, not the number of flies.
Access and safety
From the highway between Logan Lake and Ashcroft, near the west end of the copper mine, turn onto the Laura Lake road and drive about 7 km, then turn left and carry on to the 14 km mark at Calling Lake. From Calling, go north about 5 km and turn left to reach the northeast end of Big O.K. The old route through the mine property has been closed for years; stay on the signed roads around it. A four-wheel-drive truck is strongly recommended.
The recreation site on the north shore is rustic: rocky, nearly treeless and often windy, with a cartop launch. A second rustic site on the southeast corner suits trucks, not trailers or motorhomes. The lake is high, so nights are cold even in summer, and the wind across the open water can make a small boat hard work.