Aquatic plants growing in ponds and lakes are beneficial for fish and wildlife. They provide food, dissolved oxygen, and spawning and nesting habitat for fish and waterfowl. Aquatic plants can trap excessive nutrients and detoxify chemicals. Aquatic wildflowers such as the water lily are sold and planted to provide floral beauty to garden ponds.

However, dense growths (over 25% of the surface area) of algae and other water plants can seriously interfere with pond recreation and threaten aquatic life. Water plants can restrict swimming, boating, fishing, and other water sports. Water plants can impart unpleasant taste (musty flavor), decaying vegetation emits offensive odors (rotten egg smell), and algae can discolor pond waters. Dense growths of plants can cause night time oxygen depletion and fish kills. Green plants produce oxygen in sunlight, but they consume oxygen at night. Decomposing water weeds can deplete the oxygen supply, resulting in sport fish kills from suffocation. Dense plant growths can provide too much cover, preventing predation, and leading to stunted (small-sized) sportfish populations.