How To Fish Stillwaters
August 1st, 2005

Stillwaters, lakes, ponds and reservoirs are the most underutilized fisheries in the North America. Why? Because the average fly fisher doesn't know how to fish them, or where to start. Stay tuned, you too can master stillwaters! ~ LadyFisher

Productivity of High Mountain Lakes

By Gary LaFontaine

The main factors that hurt the productivity of high-mountain lakes are the cold water temperatures, hard-rock geology, and configuration (amount of shallow water versus amount of deep water). A fertile lake contradicts that profile in one, two, or three ways:

Configuration -

Most mountain lakes, made by man or glacier, sit in bowls or canyons and the shallows, or littoral zone, may be no more than a rim surrounding a plunging center. The shallow areas produce most of the aquatic food on a lake. The fishery blessed with expansive edges, flats, or shoals is richer than the normal high-mountain hole.

Geology —

Much of the Rocky Mountain region before upleft was the bottom of an ocean. In places the rock is soft fissured sedimentary limestones and sandstones. As water filters through layers of these rocks it combines with carbon dioxide in the closed spaces and forms carbonic acid—the acid in turn eats away at the rock, releasing nutrients into the water, and this rich, high-pH soup raises the basic productivity of any stream or lake it issues into. There is an abundance of food, including some forms (scuds and snails) that can't live in low-pH environments. Trout grow faster and larger.

Water temperature —

Sometimes the simple position of the lake makes a big difference in productivity. If it sits so that the early and late sun stays on the water, there is more photosynthesis among the basic algae at the bottom of the food chain. The water warms up faster in the spring and cools off slower in the fall. Two lakes can be within a mile of each other, on opposite sides of the mountain, and the one that gets more sunlight grows significantly bigger trout.

Springs entering the lake also create a warmer temperature zone. A tributary that dumps from one lake down into another might be warmer than normal if the water coming off the surface of the upper lake is heated by the summer sun. Or a lake just might sit in the path of prevailing winds that are more temperate than the surrounding mountain air.


The typical high-mountain lake has low primary productivity, colder than optimum water temperature for fish growth even during the summer, and a very brief growing season overall for the trout (as much as nine months spent under the ice). Surprisingly, such a lake can still grow a trophy specimen. A trout may live many years and, if the competition for food is low because of a small population, individual fish may get relatively large. Larger, at least, than the average high-mountain trout of 10 to 14 inches. It becomes a game to catch and release a couple of the best fish, maybe 18 inches or more, on a given body of water. A search for the biggest trout is a good way to make high-lake fisheries a greater challenge.

For me the worst of the high-mountain lakes are those overpopulated with 6- to 9-inch, thin-bodied, big headed runts. This sometimes happens in cutthroat lakes, but it is more of a problem in brook trout lakes. The spawning grounds can be too good — there might be miles of ideal gravel runs on which fish can deposit eggs. These are great lakes for a beginner. Those hungry trout rush anything that hits the water in their mad competition for food. These are also great lakes for taking out a limit of trout. On some western lakes the regulations specifically allow high harvests of fish.

The only way infertile waters can produce the occasional large fish is with minimal competition for food. Lakes with poor spawning sites are good places for big fish. Lakes with no spawning areas are even better. Biologists stock lakes without natural reproduction, and the plant dates and numbers are public record. If a water is stocked every eight years, it's going to have a lot of small fish at the beginning of the cycle and a few large fish at the end of the cycle.

Here are my final log notes on a nine-day trip up to the Beartooth Plateau with Bernie Samuelson and Ken Mira:

It's late July and we're still hitting lakes with ice patches. There is plenty of snow near 10,000 feet. The search is not just for ice-out waters. We have stocking records and we're hitting lakes that haven't received fish for a number of years. Rock Island Lake is planted every three years and - this is the third year; Black Canyon Lake is planted every six years and this is the fourth year; Lake of the Winds is planted every eight years and this is the seventh year.

Without Rufus (goat) and Cheesecake (alpaca), we couldn't carry the float tubes and extra fishing equipment, and we need everything we have with us to catch some of these fish. As it is we're each toting 55-pound backpacks. A size-20 Halo Midge Emerger on a 7X tippet is the hot combination; and we have to use neutral density lines—the cutthroats won't put up with any wind drag. None of the lakes have a lot of trout in them and the few cutthroats that are left have long outgrown the habit of rushing for food. There's a lot of just watching the water and a lot of prospecting. At Lake of the Winds we didn't catch anything smaller than 18 inches and Ken got a 24-incher. Rock Island kicked out big fish, too, but Black Canyon was a bit disappointing, with cutts up to 15 inches tops, and it doesn't seem to have the food base to grow bigger trout even in uncrowded seclusion.

Both small and large trout cruise to find the hodgepodge assortment of terrestrials and aquatic insects scattered over the surface on these lakes. There's no pattern to the rise forms, but the fish don't miss much that looks edible. This isn't fussy feeding. The fish are hunting, and the best fly is the one that will pull trout the longest distance and still trigger the strike.

Specific hatches on these waters are seldom thick enough for trout to gorge themselves, but rising fish might begin to show a preference, if not rigid selectivity, for a particular type of insect. They rush after skittering caddis adults or sip spent mayfly egg-layers. If they become fussy over any food type, it is usually a midge pupa (and just like the natural, an imitation has to hang half in and half out of the surface film). It never hurts to match the action and conformation of a prevalent prey item.

This constant feeding is the key to finding big fish. Even the biggest trout have to be obsessed with the surface from ice-out to ice-up on infertile waters. The best fish are easy to spot in the clear lakes if the wind isn't blowing.

I get up high and use binoculars to scan a lake when the water is flat. When I see either a nice trout or a big rise form, I mark the spot. That same trout will probably be in the same area even when the breeze is kicking the surface and it's impossible to sight fish. The bigger the trout the more likely it is that he travels alone and has a set territory. ~ GL

To be continued, next time: More on the productivity of lakes

Previous Lake Fishing Columns

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