Lake Fork at 59°F: the fall turnover is on

Top and bottom

Surface water: about 59°F on the latest clear reading (a few days ago).

Deep water: about 49°F by our estimate, the temperature the bottom of a lake at this latitude holds from late winter. The gap between top and bottom is about 10°F, and the warm layer has deepened to about 65 ft of 70 ft.

Lake Fork spreads over about 27,300 acres and roughly 315 miles of shoreline at full pool. The deepest water sits around 70 ft. The main targets on Lake Fork are largemouth bass, crappie and catfish. A lake this deep holds its heat, so a drop of several degrees means the season is turning, not just a cold night.

What turnover is and why the bite goes quiet

All summer a lake like this sits in two layers: warm, light water on top and cold, heavy water underneath, with a sharp boundary between them that anglers call the thermocline. Fish and bait live above it, because the deep water runs short of oxygen as the summer goes on.

Each cold night the surface loses heat and sinks, pushing the boundary deeper. Once the top is nearly as cold as the bottom, one good blow stirs the whole lake together. That mixing is what anglers call turnover.

While it happens the bottom water, with its dead leaves, silt and stale smell, comes up and spreads through the lake. The water often turns dull or tea-coloured, bubbles and bits float up, and the bite goes quiet for a week or two because the fish have lost their comfortable layer and scatter.

Where the fish go now

Start where the water looks cleanest: creek arms and the upper end, which mix early and clear early. The main basin turns over last and fishes worst while it does.

Smaller baits, slower retrieves, and a willingness to move every twenty minutes beat sitting on a summer spot. Sunny afternoons warm the shallows a touch and draw bait, so a flat with a little depth nearby is worth a look late in the day.

Who is biting

Expect largemouth bass on Lake Fork to be a solid pick. In the 50s bass still feed, but in shorter bursts, often on sunny afternoons when the shallows warm a little. They chase baitfish into creeks and coves.

Then there are crappie, in a good mood. In the 50s crappie school on deeper brush piles and creek channel edges.

Catfish are worth a try. Catfish wake up in the 50s, especially near channels and creek mouths after rain.

Where to start

On Lake Fork, start at the wind-blown bank marked on the map, fishing 4 to 16 ft. Today's northwest wind pushes bait into this bank across open water. Expect largemouth bass and crappie there; try spinnerbait or crankbait along the edge. The best window there is 1:45 pm to 6:00 pm.

On a turning lake, fish the spot early in the day before the wind stirs the surface, and move if the water there looks dull.

DamDeepest water N 3 miles

204060Depth, ft Free spot todayPlace to stay

See this spot in 3-D

Level check

The level reads 397.7 ft, 0.1 ft lower than a week ago and 0.7 ft down over 29 days. That puts it 3.1 ft below the usual level for this time of year. A steady level keeps fish on familiar spots, so what worked last week should still be close.

What the next days bring

For the calmest weather, Thursday is the pick of the next few days: sunny, wind around 10 mph and a high near 73°F. Highs slide from about 73°F to 63°F over the stretch, so dress in layers for the early start.

Circle Thursday, Friday and Saturday on the calendar: 6 of the next 7 days rate good or better. On Thursday the strongest window runs 1:45 pm to 6:00 pm, and on Friday 3:45 pm to 5:00 pm.