Lake sampling strategy

Lake sampling technique and effort has been standardized to provide a consistent province-wide approach. Sampling occurs twice a year, once in late-winter / spring (February to May, depending on location and ice melt) when the water column is in mixed conditions and once in the late-summer / fall (August to September) when the water column is stratified.

Water samples

Water chemistry samples are collected from multiple depths. For shallow lakes (<10 m), this includes one (1) discrete surface grab sample (1 m below water surface), as well as one (1) discrete bottom grab sample (1 m above sediment surface). For deep lakes (≥10 m), this includes one (1) composite from the epilimnion and one (1) composite from the hypolimnion. Water clarity is also measured as Secchi depth at each site.

Vertical profiles

Vertical profiles for temperature, dissolved oxygen, specific conductance, and pH, are obtained using multi-parameter sondes. For shallower sites, measurements are taken every meter (1 m) until the bottom is reached.  For deeper sites, measurements are taken every meter (1 m) up to 20 meters, and then every five meters (5 m) up to 45 meters.

Plankton

A one (1) liter phytoplankton sample is collected from either the discrete surface sample (shallow lakes) or from the epilimnetic composite (deeper lakes). Zooplankton samples are collected via vertical net hauls (lake surface to 30m for deeper lakes and lake surface to 1m off of bottom in shallower lakes). Depending on the site, invasive zebra / quagga mussel veliger (larval mussel) sampling may also be conducted in the late-summer / fall sampling.

Lake sampling parameters

Field	General	Major Ions
Temperature	Chlorophyll-a	Calcium Total
Secchi Depth (Water Clarity)	Hardness (Total)	Chloride Dissolved
Dissolved Oxygen	Turbidity	Magnesium Total
Specific Conductance (field)	Specific Conductance (lab)	Potassium Total
pH (field)	pH (lab)	Sulfate Total

Nutrients

Carbon Dissolved Organic	Nitrogen - Nitrite Dissolved (NO2)	Phosphorus Ort. Dissolved- P
Carbon Total Organic	Nitrogen Ammonia Total	Phosphorus Total
Nitrate (NO3) Dissolved	Nitrogen Kjeldahl Total (N)	Phosphorus Total Dissolved
Nitrate (NO3) + Nitrite (NO2) Dissolved	Nitrogen NO2 Total	Silica Reactive Dissolved

Total metals

Aluminum Total	Iron Total	Silicon Total
Antimony Total	Lead Total	Silver Total
Arsenic Total	Lithium Total	Sodium Total
Barium Total	Manganese Total	Strontium Total
Beryllium Total	Molybdenum Total	Sulfur Total
Bismuth Total	Lead Total	Thallium Total
Boron Total	Lithium Total	Tin Total
Cadmium Total	Manganese Total	Uranium Total
Chromium Total	Molybdenum Total	Vanadium Total
Cobalt Total	Nickel Total	Zinc Total
Copper Total	Selenium Total