Ponds are natural or man-made bodies of water that contain marshes, aquatic plants and animals. Of the 262 ponds located in Lenexa, we own and maintain 12 of them. The remaining 250 are privately owned and maintained.

During the year, a pond goes through several seasonal cycles. During summer months, a pond ecosystem may start to show the rapid growth of algae and aquatic vegetation. We monitor vegetative growth in all city-owned lakes, ponds and streamways. When our staff determined that the algae or aquatic vegetation reaches excessive levels, we manually remove the plants or employ other management techniques.

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Healthy algae and vegetation growth

Although algae and aquatic vegetation growth may be seen as a negative, it is a necessary occurrence in the pond cycle and is a positive sign. This vegetation provides habitat for fish and serves as a food source for many animals found in these environments. It also helps chemically balance the water quality making for a healthy pond ecosystem. Examples include:

• Duckweed

• Water lily

• Water primrose

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Unhealthy algae and vegetation growth

Certain species of aquatic vegetation are not considered native to the United States and are extremely aggressive and invasive. In large quantities, they can pose a threat to a pond ecosystem. While this type of pond vegetation is considered undesirable, our City Code does not require the removal of any vegetation naturally forming in a pond ecosystem. An over-abundance of some algae species can be dangerous to people and pets. When a health risk is present, private pond owners are required to report it and up warning signs; and we will put up signs at city-owned ponds and lakes. Examples of unhealthy vegetation include:

• Curly-leaf pondweed

• Blue green algae

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Algae and aquatic vegetation examples

Arrowhead

Arrowhead is a native, perennial plant with arrowhead-shaped leaves and a tall spike of white flowers. It can grow in shallow water or in wet areas. The tubers of this aquatic plant are prized food by ducks, geese, muskrats and beaver.

Blue green algae

Blue green algae can be harmful to the health of humans and animals when an algal bloom is present. Blue green algal blooms occur most often in summer months. If you suspect you have seen blue green algae in a body of water or stream way in Lenexa, please contact the Justin Steudemann Stormwater Specialist at 913.477.7500.

Kansas Department of Health and Environment: Algae blooms in the state

Cattail

Cattail can grow 5 to 10 feet tall in shallow water or boggy areas with no standing water. Flowers form in a dense, dark brown, cigar shape and are called ‘catkins.’ Cattails are a native, invasive species that spread rapidly because each catkin can contain hundreds of thousands of fluffy seeds that are easily spread by the wind. Additionally, this plant sends out underground roots (rhizomes) that form new plants. The roots and lower leaf are often consumed by muskrats, beaver and geese.

Chara 

Chara is a non-flowering algae that grows below the surface of the water. It has a crunchy, grainy texture and can have a musty odor. It provides an excellent habitat for fish and other macro-invertebrates. It is non-toxic but can get to excessive levels.

Coontail

Coontail is a rootless, submerged, perennial plant that often forms dense colonies. The branch tips and leaves resemble a raccoon’s tail. Coontail provides excellent habitat for fish and invertebrates. The fruits of coontail are consumed by ducks and it is considered a good food for wildlife.

Curly-leaf pondweed

Curly-leaf pondweed is a perennial plant that is native to Europe. It can be an aggressive invader that can cover large portions of ponds and lakes. When occurring in excessive quantities, stormwater staff will remove from city-owned bodies of water. This plant can stick to fishing equipment and boat components, so great caution should be exercised to minimize the spread of it from one body of water to another. Curly-leaf pondweed has little nutritional value to wildlife.

Duckweed

Duckweed is a very small, free-floating, seed bearing aquatic plant. Each plant contains one to three leaves that are 1/16-inch to 1/8-inch in length, and a single root protrudes from each leaf. It tends to grow in dense colonies in calm water, undisturbed by wave action. This species can be an aggressive pond invader and if colonies cover the water surface for an extended period of time, a fish kill can occur due to oxygen depletion. Many kinds of ducks consume duckweed and they are often the cause of it being transported between bodies of water.

Filamentous algae

Filamentous algae resembles wet wool and is commonly referred to as pond scum. It begins growing along the bottom of shallow water or attached to structures. It then releases, floats to the top and forms into large floating mats on the water's surface. It is non-toxic but can exist in excessive quantities. It also provides habitat for fish, frogs and other invertebrates. 

Water lily

Water lilies are perennial plants that often times form dense colonies on the water surface. Their round leaves are typically 6 to 12 inches in diameter with a pie shaped notch. Flowers grow on stalks that rise above the leaf or they may float on the top of water. Flowers can be white or yellow in color and are very fragrant. Submerged portions of the aquatic plant provide habitat for fish and invertebrates. Various parts of the plant are consumed by amphibians, reptiles, ducks, deer, beaver, muskrat and other rodents.

Water primrose

Water primrose is a perennial plant that grows along the shoreline and forms runners up to 16 feet that float across the water surface. It produces shade that inhibits the growth of filamentous algae in shallow waters. When in bloom, small yellow flowers are produced. Ducks and other waterfowl consume the seeds of this plant.