Water Quality is usually assessed based on various factors, such as clarity, health safety, chemistry, life forms supported, anthropogenic pollution, salinity, acidity, temperature. On all of these measures, Chandos can be considered a healthy lake.
The Trophic Status of a lake refers to the level of nutrient enrichment and the attendant water clarity as affected by algae and weeds. The main nutrients that affect the biological productivity of the lake are phosphorus and nitrogen. An oligotrophic lake is nutrient poor and the clarity is very high. Towards the other end of the Trophic scale a lake is termed eutrophic, being nutrient rich, usually weedy, and with very little clarity.
Chandos is borderline oligotrophic-mesotrophic, with Secchi depths around 5m, phosphorus in the 10 µg/L range, and Chlorophyll a (chla) around 3 µg/L. (Chla concentration is a measure of planktonic biomass)
For a very thorough and readable backgrounder on Trophic Status, see the Ontario MOE handbook 87-lakeshore-capacity-assessment-handbook-en-1. In particular Technical Bulletin No. DESC-4 on page 95.