Using Water Conditions to Narrow Your Search

by Dan Craven

Water conditions are directly affected by our weather (short term) and climate (long term). We frequently take water conditions for granted; more so than presentation, boat control or location of the fish. There are certain times of changing or changed water conditions that over-ride all other factors while searching to contact and catch muskies.

Algae-thick water is one of these conditions, and one of the most common. Silt-laden water from strong wind is another. Other examples of altered water conditions affecting fish location and activity level are temperature variations/barriers within a body of water, extremes in water level over a short period of time or radically changed from the norm (long term), and altered oxygen conditions within a lake or specific area of a lake.

Anyone who has fished Lake of the Woods has probably seen the “pea-green soup.” Lake of the Woods is so productive (nutrient-rich) that an algae bloom can occur any time there is an extended warm spell. These blooms can occur any time from May to October, but the odds increase during the warmer months of July, August and September. Lake of the Woods is used as a prime example that many people can relate to, but most lakes and reservoirs experience an algae bloom that varies (by lake) due to its water’s chemical make-up. Some lakes have more nutrients than others‹promoting a more developed algae bloom. When some lakes bloom, you can see a few small algae specks floating in the water column. When other lakes bloom, the algae is so thick that it changes the water clarity from 6-10 feet to 1 foot or less. When water conditions change, fish behavior changes. It is a direct relationship. River fishermen have known this for years, but it also affects our lake fishing.

When faced with an algae bloom, you must find clear water. I regularly fish a number of lakes that experience algae blooms. On all of them, over a number of years, with various presentation techniques, and varied depths/locations fished‹my muskie contacts/catches increase with the increase in the clarity of the water I fish. Am I stressing this enough? It must be noted that this is consistent with the findings of many other experienced and trusted muskie fishermen.

Algae blooms can occur over whole lakes or portions of lakes. This is true on large and small lakes. Last summer I was guiding on a fairly small lake in North-central Minnesota. Wind conditions (SE at 5-15 mph) were blowing almost all the algae to the northwestern half of the lake. These conditions literally created a line across the lake. The northwestern two-thirds of the lake had a water clarity of less than 1 foot. The southeastern portion, 3 to 5 foot water clarity.

Final count: three fish were landed by my two clients and numerous fish were sighted in the clear portion of the lake, but no fish were sighted or caught in the “dirty” water. All three fish that were boated were in the closest cabbage weed bed to the bloom-line on the east side of the lake. This was no fluke. The traditionally best weed beds of the lake were within the bloom, yet 100 yards out of the bloom the fish were very active. This brings up a point about algae and some of its characteristics. Algae generally “floats” and absorbs light in the upper portions of the water column. (Most of the algae is in the top several feet of water.) It absorbs/uses oxygen. It blocks out some of the sunlight and reduces visibility in the water whether looking down, into the water, or through the water. Algae can be blown from one area of the lake to another. If winds are extreme the algae can be mixed in the water column, but light to moderate winds are the conditions that move it across the surface of a lake, rather than mix it down into the water column. (Algae can also be dispersed throughout the water column by current.) Different areas within large lakes can have different water colors and productivity levels, based on their respective algae blooms.

Having more knowledge about algae will help you contact more muskies. Without being specific about “spots” on Lake of the Woods (as an example), the following will generalize several areas that will have clear water when much of the lake is in bloom. These same rules apply on smaller lakes throughout the U.S. and Canada.

Find current areas. Current disperses algae throughout the water column. There is still as much algae in the water, but it is not only on the top five feet. It is dispersed from the surface down to as deep as the current mixes the water; thus “thinning” it out. The water is clear and the muskies will probably be biting.

Certain bays or portions of the lake have varied water clarity, temperature and productivity levels that delay or totally negate a bloom occurring. You have to drive your boat around the lake and find these areas. Usually they are somewhat secluded or divided from the main portions of the lake by a bottleneck or channel.

Finally, if there is no getting away from the bloom, find a section of the lake that is the clearest and fish the leeward side of that section. This is where the water should be the clearest. If you are on a small lake, you may want to try a different body of water…


Silt is nothing more than sediments that are suspended or mixed in the water column. These sediments may come from light organic material lying on the bottom that are stirred up by waves or currents or from earthen material that is being mixed into the water by large waves or rainfall (erosion). Wind is usually involved with silt, creating silt lines downwind from a point or structure that the wind is blowing across. Silt lines are more prevalent in years of high water due to increased erosion.

In my experience, silt is totally different than algae. Silt can be an advantage. Silt does not use up oxygen, even though it can reduce the water clarity. I believe that this oxygen factor is the main difference. The whole food chain frequently gathers on silt lines. Minnows, perch, walleyes, pike and muskies will gather where the clear meets the dirty water‹and all are usually active and biting.

Canadian lakes that have been burned over (forest fires) in the last 10-20 years offer prime examples of where erosion and silt lines can form when the wind comes up. Much of the plant community near the water line has been burned and there are no large roots to slow erosion. Throwing a variety of lures into the silt line and pulling them out can produce devastating strikes from muskies. Walleyes and pike hitting large muskie lures is not uncommon. Some of my largest walleyes have come under these conditions on bucktails, crankbaits and jerkbaits.

Oxygen-depleted Water

This next situation is not common, but when it does occur it can be either beneficial or detrimental to the fisherman. Oxygen levels can vary by time of day in certain areas of lakes, especially in small, primarily shallow lakes. Understanding the basics of how oxygen affects fishing is crucial‹especially in night fishing situations.

Plants produce oxygen during daylight hours. Bacteria in our waters use oxygen. If an area is quite weedy and the water is fairly shallow and warm, bacteria can use up available oxygen at an amazing rate. During low-light or night periods, the bacteria can substantially reduce the amount of oxygen in an area. The situation where this comes into play (in my experience) is usually a shallow, weed-choked bay of a quality muskie lake.

Muskies (most fish, for that matter) are much more active and willing to feed in water with good oxygen levels. When the oxygen levels decrease, the muskies either become lethargic or they seek out areas with more oxygen. In my experience, there is little hope of catching the lethargic fish. Muskies in weed-choked areas act as if they are sleeping (I have spent many hours spotlighting, without fishing, after dark; observing fish location/activity.) They usually need to be poked or touched to even coax them into moving. These are the fish that you can find very active during the daylight hours; at night they either move to oxygen-rich areas or become lethargic.

During the night, when shallow water plants are not producing oxygen, it is not uncommon to find the more active fish in channel areas, holes in the weedbeds, or at the edges of the large weed flats or bays‹searching out and feeding in areas that have more oxygen available. These fish will readily strike and have totally different “attitudes” than fish merely 50 yards away in the heavy, shallow weeds.

One of my best night fishing experiences was in a situation involving oxygen depletion. During the evening two clients and I caught three muskies in a necked-down, weed-choked bay. These fish were in the slop, and there were a lot of fish in a fairly small area. We were spooking fish quite often when our lures hit the water. The last strike we had was about five to ten minutes after the sun went down.

My clients wanted to fish until about 1:00 A.M. We continued fishing without any luck until we started fishing a channel that ran through this bay into another part of the lake. The channel was twenty feet wide with a very light current. It was loaded with fish. So was the sand beach area at the mouth of the bay. Four more nice muskies were boated by 1:00 A.M. with five to seven more strikes. The weeded areas were quiet. The “open” (oxygen-rich) areas were alive with feeding muskies. We also heard at least twenty surface strikes at natural forage that evening in the channel and near the sand beach. The conditions allowed us to set up a foolproof, easy pattern.

Several other muskie “hounds” have shared similar instances with me. Dave Maas, who works for The Hunting and Fishing Library (Dick Sternberg’s publications), relayed a similar situation to me about a shallow, weed-choked lake in Wisconsin. His experience, which happened about ten years ago, sounded intriguing to me, but I thought I might never be lucky enough to experience similar conditions.

In closing…

Bottom line: Water conditions greatly affect our fishing. Some of these changes are major, some are minor. Water conditions affect where we fish, when we should fish certain areas, and the presentation we use to catch our quarry. Few observations are too small to take into account while we are attempting to figure out a pattern, because it is very evident that miniscule organisms or changes in water conditions can greatly impact our fishing experience.

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