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.

Accumulated pollen along the shore can sometimes be mistaken for algae or pollution.
Accumulated pollen along the shore can sometimes be mistaken for algae or pollution.

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.

Natural Shoreline Habitat in Severn Sound - Scenic

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.

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