An oligotrophic lake is the first stage a lake will go through. This type of lake is nutrient poor. Often times you can see to the bottom of this type of lake even if it is very deep. There will be a high level of dissolved oxygen in the water because there are no fish, aquatic plants, and other organisms that would use the oxygen. These lakes are usually deep as sediments have not yet built up on the bottom of the lake.
This is Little Crater Lake in Portland, Oregon. It is 45ft deep with crystal clear waters. This is a great example of an oligotrophic lake.