Floating Pollen
In spring and early summer, many trees—like pine and birch—as well as grasses, release large amounts of pollen into the air. This is a natural part of plant reproduction. Pollen grains are very light, so they’re easily carried by the wind to help fertilize other plants.
As the pollen travels, it often settles on surfaces like cars, decks—and water. Pollen is hydrophobic, meaning it repels water and floats on the surface of lakes, rivers, and ponds.
Pollen floating on water is generally harmless to people, pets, and aquatic life. It may look unusual, but it is a natural and temporary occurrence. In some cases, direct contact with water containing pollen can cause irritation to the skin, eyes, or other sensitive areas in people with pollen allergies.
Pollen on the water can look like:
A yellowish film or slick, sometimes mistaken for algae
Clumps or streaks, especially in areas like coves
Stains on rocks or shorelines after rain or wave action
Warm, dry, and breezy conditions help pollen travel farther—and settle more visibly on water surfaces.
What to Look For
Differences between Pollen and Blue-Green Algae
colour
pollen
Pale yellow, tan, or light brown
Blue-Green Algae
Bright green, blue-green, sometimes reddish
Pattern on water
pollen
Thin film, streaks, or scattered clumps, leaves yellow stains on rocks or docks
Blue-Green Algae
Thick mats, blobs, paint-like scums, or pea-soup-like water (depending on species and conditions)
Location
pollen
Often near shorelines, coves, or calm areas
Blue-Green Algae
Can cover large areas, especially in still water
Texture
pollen
Powdery or dusty
Blue-Green Algae
Slimy, slippery, or smooth
smell
pollen
No noticeable odor
Blue-Green Algae
May smell musty, earthy, or unpleasant
Timing
pollen
Spring to early summer
Blue-Green Algae
Slimy, slippery, or smooth
risk
pollen
Generally harmless, unless a person has pollen allergies
Blue-Green Algae
Can produce toxins when algal blooms are present
Visit our All About Algae page for more information about algae.
Over time, pollen grains absorb water, become heavier, and sink to the bottom. There, they settle into the sediment of lakes, rivers, or ponds. In large amounts, pollen can even leave yellow stains on rocks along the shore, on docks, and on boats.
While it might seem like a seasonal nuisance, pollen is critical for the reproduction of trees, an important food source for insects and some animals, and is a powerful tool for scientists. When pollen settles into lakebed sediments, it can stay preserved for thousands of years! By studying these layers, scientists can identify what kinds of trees and plants were growing in the area at different times. This helps them understand how the climate and environment have changed over time.