1. Classification of Lakes
“Limnology” – the study of Lakes

2. Lake size and depth can change over time
Lakes can fill in with sediment without human interference.
The process is called Eutrophication.
Lakes can be classified by their progression through this process.

3. Oligotrophic Very Low nutrients Deep lakes – 60-100 feet deep
Very Clear water –Secchi reading of more than 12 feet
Less plant and animal growth
Usually poor fishing but GREAT for scuba diving and swimming

4. Oligotrophic

5. Oligotrophic

6. Mesotrophic Moderate levels of nutrients
Some Clear water – Secchi reading of 8-12 feet
Moderate plant and animal growth
Average Fishing and swimming lakes
Some algae and plant growth around the shoreline with open water in most of the lake

7. Mesotrophic

8. Mesotrophic

9. Eutrophic High levels of nutrients
Mostly murky water – Secchi reading of 3-8 feet
High level of plant and animal growth
GREAT fishing
Green or dirty looking – plant dominated
Lots of sediment in the lake bottom

10. Eutrophic

11. Eutrophic

12. Hypertrophic Extremely high levels of nutrients
Algae blooms – Secchi reading of 0-3 feet
High level of plant and animal growth
Poor fishing, often too much nutrients to support a healthy fish population
Overrun with plants and algae, often caused by sewage and fertilizer runoff
Smelly water and muck covered bottom

13. Hypertrophic

14. Hypertrophic