What is trophic status?

Smoke on the water

Plants and algae support fish and insects in a lake, and nutrients such as nitrogen and phosphorus support plants and algae. Trophic status is a measure of the amount of nutrients in a lake.


Oligotrophic lakes are poor in nutrients. They are deep and clear, with rocky shores and few rooted plants. Oligotrophic lakes do not produce many fish.


Eutrophic lakes are rich in nutrients. They are green and weedy, have mucky shores and bottoms, and can be plagued by algae blooms. Eutrophic lakes produce lots of fish.

Mesotrophic lakes are in the middle. They have more diverse aquatic life than oligotrophic lakes but are not as nutrient rich as eutrophic lakes.

The balance of nutrients in a lake changes over time. As they age, lakes slowly fill with sediments and organic matter, a natural process called eutrophication. Eutrophication can be greatly accelerated when additional nutrients enter a lake via runoff from lawns and streets, septic systems, or nearby agriculture.

Data on the trophic status for Victoria’s lakes is limited, but reports published by the BC Lake Stewardship Society indicate that:

  • Langford Lake has generally shown to be eutrophic.
  • Prospect Lake, monitored from 1986–2011, was mesotrophic for 14 of those years and oligotrophic for the other five.
  • Fork Lake was mesotrophic in 2000 and oligotrophic 2001–2006.

Learn much more in the full Lakes of Victoria, BC guidebook!

Cover of Lakes of Victoria, BC.

In the full guidebook, discover where to:

  • Walk: enjoy lakeside strolls & boardwalks.
  • Hike: discover single-track trails & scenic views.
  • Swim: find the best beaches to soak up the sun.
  • Fish: learn about stocking trends and piers.
  • Paddle: explore shorelines, and hidden bays.
  • Bike: plan your next route and hit the trails.

Along the way you will meet the animals and plants that call these lakes and watersheds home, unearth forgotten place names, and learn stories of days past.

The book is full of useful maps, access information, and local trivia to get you started on your next family day or great adventure.

From locals to visitors, everyone will learn something new about the freshwater lakes that bring Victoria to life.