It was one of the first times I fished this lake. Its deep, clear, relatively sterile waters held an excellent population of lake trout, plus a marginal population of pike and walleyes. As far as numbers of pike and walleyes, it was one of those "there aren't too many in the lake, but when you find hen they are big" type of lakes.

After a fairly slow hour of fishing along a windswept bank I decided to head across the lake. I turned up the power on my Eagle flasher unit and took off. About halfway across the lake I noticed the fairly narrow bottom signal at 55 feet suddenly got wider, then narrower again. There was no depth change, but the wider signal indicated an area of midlake hard bottom due to a more powerful signal bounce back.

I returned to the hard-bottom area, tossed out a floating marker, and began following the harder area to my right. After 75 yards it petered out. Now it was time to check to the left of my fishing marker. The bottom began coming up--45 feet...40...30...20...short grass at 17-18 feet indicating some fertility--the weeds! A beautiful deep "cabbage" weed bed started at about 14-15 feet.

I slowly motored around the perimeter of the weed-covered hump at the 20-foot level and tossed two markers out along the upwind side of the structure abut 75 yards apart. We carefully motored upwind of the markers, shut off the motor and began our drift across the structure. In seven or eight drifts we boated 12 pike over 8 pounds, including fish of 17, 18, and 21 pounds. I found the mother lode spot of this particular lake, a real big-fish haven that still produces.

This was one of many instances where a section of flatter hard bottom led me to a key nearby area. And most of the time these spots are found by watching your sonar unit and making sure the power is on high enough to send back the proper signal.

Did you ever wonder why a hump or similar high spot existed along the bottom? When something sticks up like that, it's usually harder than the surrounding area. The firmness allows it to stand tall.

Often a high area doesn't immediately get soft once its sides taper to the surrounding basin. Often hard bottom exists for quite a distance from the rise. It was this type of situation I'd run into.

If you're motoring across a lake and run across a rise, it's easy to note and check out. But if you miss the structure, you can often note surrounding hard bottom which can lead you to the structures.

The key to recognizing this condition is knowing it exists and having a depth finder that tells you harder bottom is below.

Understanding how harder bottom often leads to higher spots is also a great navigational aid on reef-studded waters. If I'm motoring through a dangerous area to travel, "one eye" is always glued to the depth finder. As soon as that bottom shows hard I back off the throttle. Many times the bottom has quickly risen to the surface. If I wasn't' paying attention I'd have found a place to knock off my lower unit, as opposed to a place to fish.

Isolated areas of hard bottom don't have to be in deep water to be productive. They may be in just a few feet of water and be very good.

Have you ever fished a wide expanse of shallower water mixed in with at least some cover and wished there was a faster way of eliminating these flats? Good anglers usually try to isolate a specific shallow water pattern or two and often isolated areas of hard bottom play a part in their success.

Many times weed growth or weed beds with numerous holes in them are key areas. Often these openings are caused by a soil content that's not conducive to good weed growth--hard bottom.

Have you ever noticed how areas of tall brown bulrushes are so-called producers, but smaller areas of green reeds are the key? Or tall reeds may be okay but isolated patches of shorter pencil reeds really produced the fish? Or smaller patches of arrowhead exist around an area of big wide leafed lily pads. These smaller members of the "pad family" grow on a little firmer bottom and are even more attractive to the fish. This situation is the same as the green reeds were to the brown bulrushes, or the pencil reeds were to the taller reds.

An unusual hard bottom but one that can be very productive is a hard-bottom hole. Imagine that you're crossing the lake and the bottom is flat and soft at a constant 15 feet. You've gone several hundred yards and the sonar has fed back the same "nothing" signal. All of a sudden the bottom shows hardness by a wider signal, plunges down to 20 to 25 feet, still showing hard, then comes back up, only to flatten out to a soft 15-foot flat again.

If there were an active, large spring or an underwater discharge in a lake, what do you suppose it would look like? Most likely it would be a hole in the lake's bottom. And most likely the bottom of the hole would also be hard because the flow is keeping the hole free of sediment. A soft-bottom hole with a hard surrounding area could be a spring with a small flow, or something as weird as a bomb crater. I've seen all these situations and all can be productive...as long as the bombing has ended.

Current and isolated hard-bottom areas go together like ham and eggs. Often the combination of current and structure and/or cover equals harder bottom. Actually these combinations don't create harder bottom as much as they expose harder bottom under a silted area.

Rock jetties or wingdams in rivers are perfect spots where current opens up harder bottom areas. Around the tip of the structure the area is usually swept clean of silt. Just up current from where the flow breaks over the rock-studded structure also has potential. The hole just down-current from the jetty or wingdam may be silt laden and barren of fish, but when it starts coming up and meets the surrounding current-sweeping flats, the bottom hardness and the potential increases.

On dishpan type lakes with little or no cover deeper than three or four feet, many anglers have trouble catching fish once the waters warm up. And if this shallow weedline drops a foot or two due to low water, "fishing really gets tough." But not really, unless the lake becomes oxygen starved and the fish slow down until conditions improve.

What usually occurs in warmer weather in these structureless soup bowl shaped lakes that have only shallow cover and/or shallower drop-offs is that fish go deep. If the lake's maximum depth is only 10 to 20 feet, game fish are generally related to the deepest harder bottom in the lake.

Generally, if the lake's deepest water is 18 to 20 feet or so, the key hard bottom areas will usually be in the 8- to 15-foot range. Remember, the absolute deepest part of a lake is the bottom of the bowl--a collector of things that fall into it. With a lake, sediment collects in the deepest waters, so the adjacent slightly shallower waters are key. Look for any slightly higher areas (six inches can be okay), short grasses or algae, scatter rubble or rocks, a little bit quicker tapers or small lips.

Learn to recognize these hard-bottom conditions. They can pay off when nothing else works.