The last 20 years have brought about a vast change in the size and appearance of Lake Koshkonong.

Formerly it was nothing but a flooded marsh with the Rock River running through it. The water, with a maximum depth of 1½ feet, was very clear, and fish and game exceedingly abundant. The lake was so densely filled with duck foods and other aquatic and marsh plants that boats had to be poled and not rowed through.

Furthermore, there was not enough open water to allow the wind to produce any waves. At that time there were no carp in the lake.

At the present time, the lake is all open water averaging 5 feet, and so murky that it is impossible to see to a depth of more than 2 or 3 inches.

Now there are practically no bluegills, perch or bass left, while pike, bullheads and dogfish are about the only fish caught, and those in very small numbers. Buffalo fish and garfish are very common, while carp are so abundant they seem to keep the whole lake disturbed and densely filled with fine mud.

Except for the marshes, absolutely the only sign of vegetation in the lake itself is an occasional spear of Scirpus fluviatilis rising above the water a quarter or half a mile from shore.

The lake is so large for its depth that now the slightest wind will raise such choppy waves that the lake becomes dangerous for boating. These waves keep the water stirred up and greatly increase the water action upon the shores.

All the vegetable food for fish seems to have entirely disappeared from the lake proper. ... The carp are constantly rooting around in the mud about the marsh vegetation. Of course, when the mud has all been removed from the roots, the water will complete the destruction. ... Some think the carp could never have reached all that vegetation if the water had remained at its original level.

This brings up the discussion of the change in water level. In the neighborhood of 1830, a dam was built at Indian Ford, about seven miles below the lake on its outlet, Rock River.

This dam did not make much difference in the water level, for it was used chiefly to hold back the lake water as sort of a reservoir to furnish an even power supply for various mills on the river below. Thus the water was gradually let out so there was no remarkable change from the previous seasons.

In 1917, a new dam was built, supposedly the same height as the old one but actually quite a bit higher. Since that time, the water level has risen probably 18 inches, which has caused some $5 million damage to surrounding farms and property.

The spring freshets always used to flood the land adjoining the lake and river, but this flood would last only about two weeks. The very first spring after the new dam was completed, the water rose 6 feet higher than it ever had before and did now flow entirely off for two months.

This caused all the farmers and land owners to get together and attempt to bring court action against the owner of the dam. This resulted in the Wisconsin Railroad Commission requiring the owners to take off half a foot from the top of the dam.

The dam had been built without gates, so the commission requested them to put in 40 feet of gates, each 5-feet deep. ...

The original charter for Indian Ford dam (about 1850) states that it must not raise the water more than 6 feet above its original level, but further must not be allowed to flood any of the property bordering the lake or river.

Although perfectly evident to all the local people, it is difficult to definitely prove in court that the dam is the actual cause of all the flood damage in the spring and even in the midsummer after a heavy rain. ...

A lowering of the water level in the lake would most certainly prevent further destruction of land and would aid in bringing back the vegetation. ... Perhaps the best remedy of all to prevent destructive high water is to lower the top of the dam. That, together perhaps with increasing the number of gates, would do a great deal towards letting the flood waters off quickly enough to prevent prolonged damage to adjacent property.

To sum it all up, the factors that seem to have been the cause of the decided change in Lake Koshkonong are the carp and high water. Elimination of these factors may bring the lake back to its original importance for hunting and fishing.