The first settlers in Medical Lake found a lake that appeared healthy and unique for its healing qualities. The town thrived on this concept for several decades. By the 1940’s the lake started to become stagnant and almost unable to sustain any form of aquatic life at all. The lake at that time also became unpopular to waterfowl, most wildlife and most human usage as well. The loss of water quality in Medical Lake was thought to be due primarily to a combination of human influence and the fact that this is a spring fed lake.

The underground springs do not contain the life sustaining oxygen; that can only be provided by surface inlets (streams). The result of these circumstances over a period of time was an extremely heavy growth of oxygen starving blue green algae that choked out the oxygen rich green algae.

The lake remained stagnant until public utilities were installed in the town during the 1950’s and 1960’s. At that time the lake began to regain some of its health. In the late 1970’s new technology provided for a chemical lake restoration product known as "Alum." The city leaders invested in the treatment and by 1980 the blue/green algae had virtually diminished and a new oxygenated and healthy lake existed.

The lake restoration brought on a huge surge of new activity in the city as grants obtained led to the Waterfront Park development and the lake trail system. Thousands of visitors returned to Medical Lake to enjoy a healthy lake and an outstanding natural recreational resource. During the mid 1980’s and early 1990’s the city invested in a long-term water oxygenation system known as "Hypolimnetic Aeration" (notice the floating platforms in the lake). The aeration system distributes oxygen throughout the lake after the unit receives compressed air through lines from a land based compressor station.