Provincial Ambient Water Quality Monitoring

Provincial Ambient Water Quality Monitoring

Physical, chemical and biological data are collected biannually from a wide variety of B.C. lakes to determine current water quality status and to understand long-term trends.

Currently, 53 lakes (74 lake sites) are sampled, which cover various ecoprovinces and span wide gradients of area, depth, and trophic status. Explore these sites in the interactive map below.


Long-Term Lake Trends

View map in full-screen

Lake Water Quality Trend Data

Analysis is underway regarding these topics:

Sampling Strategy

Lake sampling technique and effort has been standardized to provide a consistent province-wide approach.

Lake Sampling Strategy Diagram

Sampling is conducted  biannually

  • Late-winter/spring (mixed conditions): February to May, depending on location and ice melt
  • Late-summer/fall (stratified conditions): August to September

Water chemistry samples are collected from multiple depths

  • Shallow lakes (<10 m) = 1 surface discrete grab sample (1 m below water surface) + bottom discrete grab sample (1 m above sediment surface)
  • Deep lakes (>10 m) = 1 epilimnion composite + 1 hypolimnion composite

Vertical profiles are obtained using multi-parameter sondes (temperature, dissolved oxygen, specific conductance, pH)

  • For shallower sites, measurements are taken every 1 m until the bottom
  • For deeper sites, measurements are taken every 1 m until 20 m, and then every 5 m until 50 m.

Water Clarity

  • Measured as Secchi depth


  • Phytoplankton: 1 x 1 L sample
    • Shallow lakes = discrete surface
    • Deep lakes = epilimnetic composite
  • Zooplankton: 1 x 30 m vertical net haul (or 1 m off bottom for shallower lakes)
  • Invasive zebra/quagga mussel veliger sampling (Late-summer/fall sampling only)