Net tow samples are collected using a Wildco 40-mesh size, 12.7-cm diameter net (or the equivalent). They are generally collected from a boat over the deepest portion of the lake. Phytoplankton abundance are estimated based on the number of tows, the depth of the tow, and the area of the net opening, assuming all water above the net passed through the net during the tow. Lugol’s solution is added as a preservative.