Algae is an issue for lakes and ponds of all sizes, and once it has taken over a lake or pond, getting rid of it can seem like a never-ending task. Algaecides can offer short-term results, however, proactive lake and pond management is the best solution for long-term success.
A proactive approach to solving large pond and lake algae works with nature to solve the problem, to naturally balance the ecosystem, and improve the water quality of a large pond or lake.
What Causes Algae in Large Ponds?
Many large ponds and lakes, particularly those that are not professionally managed, contain an excess of nutrients, primarily nitrogen and phosphorus, which feeds the growth of pond weeds and algae. If nutrient levels are not balanced, muck and sludge can build up over time. Harmful types of bacteria or parasites can find a home in the muck and sludge, creating an unhealthy environment in the large ponds and lakes.
Excess nutrients are typically driven through run off created by urban development and human activity. Fertilizers, sewage, chemicals, and animal waster from surrounding areas can all make their way into the lakes and ponds via stormwater runoff and contribute to nutrient loading in waterbodies.
With excess nutrients, algae growth becomes out of balance with the other plants in the waterbody. They then take over wildlife habitats and shade out native species by blocking sunlight from entering the depths of the large pond or lake.
Without water movement, coupled with high nutrient levels, filamentous algae quickly take hold in warm, shallow water. This happens because of the abundance of nutrients and the warm water conditions algae thrives in. Many people call this algae pond scum since it has the appearance of greenish-yellow muck floating on the surface of the water. This is a bit of a misnomer since the algae also grow on the bottom of the water body.
As the algae take over large lakes and ponds, the healthy ecosystem is damaged, and fish and other wildlife may begin to die off. This further degrades the ecosystem as it creates more food for algae and continues the cycle of overgrowth.
The Importance of Controlling Algae in Big Ponds
A big pond can easily become out of balance with algae growth that produces harmful side effects. This can lead to depletion of oxygen in the water and a release of toxins. Without proper management, algae overgrowth can quickly get out of control and disrupt the waterbody’s ecosystem.
Dense algae mats on the water can result in less light penetrating the water column, which may hamper the growth of beneficial aquatic plants and reduce the amount of dissolved oxygen in the deeper layers of the waters in large lakes and ponds. The beneficial aerobic bacteria in the soil will start to die, causing the waterbody to become even more unbalanced. As water quality continues to deteriorate, fish kills may occur, further degrading the water quality of the large lake or pond and effectively rendering it unusable.
Signs of Algae or Cyanobacteria Problems in Big Lakes include:
- Foul-smelling water
- Skin rashes after swimming or contact
- Death or sickness of pets
- Dead waterfowl or fish
Algal blooms can be easily identified by a change in coloration of the lake or pond’s water due to the increased density of pigmented algal cells. Many kinds of algae can create blooms, however, some harmful cyanobacteria or blue-green algal blooms have the capability of producing dangerous toxins that affect other organisms, including pets, livestock, and humans.
How to Identify Types of Algae in Large Lakes and Ponds
Below is a quick guide to identifying the types of algae commonly found in large lakes and ponds. It is recommended to work with a professional for proper vegetation and algae identification.
Blue-Green Algae: this type of algae can consist of a single cell or be filamentous or colonial and can rise up to the top layer of water bodies creating a layer of scum. It poses a serious threat to aquatic life in the pond as well as people and pets you use it. If the pond looks bright green like pea soup, this is a good indicator of a blue-green algae bloom. Also, if the mats look dark green or black, this may be a filamentous blue-green algae.
Muskgrass: because of its leaf-like and stem-like appearance, this type of algae looks like land plants. It can benefit water quality and create valuable fish habitat, however, they run the risk of overgrowing without management. These grow on the bottom of the pond or lake.
Filamentous: like most algae, this type provides food for fish, insects, and fish. It grows into a mat that looks like wet wool floating on top of the waterbody. It can quickly take over any waterbody and cause ecosystem imbalance without proper management.
Nitella (Stoneworts): this type of algae has stems that are comprised of chains of single cells shaped like tubes and cells that look like whorls branched off from the main stem. It provides food for wildlife and fish, but under certain conditions, it can be a nuisance to swimmers and boaters.
Planktonic Algae: Also known as Green algae, this type of microscopic algae floats in the water and is the foundation of every waterbody’s food chain. It can cause the water to look brown, reddish, or green and is sometimes mistaken for muddy water. Blooms can happen rapidly, changing the color of a clear lake within a couple of days. Because of its importance to the food chain, it needs to be carefully managed.
Large Pond Algae Control: Proactive Management
Although a large lake or pond may seem to be doing well for years, ongoing management is crucial to ensure its continued health. The large volume of water that these waterbodies often contain in relation to fish and organic matter in them can mask many issues for a while. Sooner or later, these issues will rise to the surface, and the water body will become extremely ecologically unbalanced.
Water quality issues that have been percolating over time can become apparent suddenly. This is why keeping a large lake, or pond healthy is an ongoing process and not a one-shot deal. It doesn’t happen overnight, and it can’t be solved overnight. It takes time, but the issues can be resolved, and smelly, stagnant, unusable large lakes and ponds can be returned to health.
For existing algae issues, mechanical harvesting can be used to selectively remove large amounts of aquatic vegetation and algae and quickly bring them under control. EPA registered aquatic herbicides may also be used for algae control and should be applied in proper doses by licenses professionals.
In addition, the following proactive measures can be implemented to help improve water quality, thus reducing the likelihood of future water quality issues such as algae blooms, aquatic weeds and foul odors.
- Adequate pond aeration
- Beneficial vegetative buffers with native plants
- Regular treatment with a beneficial pond bacteria
- Biological aquatic weed control via fish stocking
- Nutrient mitigation technologies
A fountain and aeration system keeps the water moving, and helps improve dissolved oxygen levels. Fountains are also stunning focal points in large lakes and ponds, creating value for the communities surrounding these lakes as they also aerate the water and help prevent algal overgrowth by improving overall water quality. In addition, submerged diffusers and surface aerators help circulate water and prevent the dangerous low-oxygen levels that damage the lake’s ecosystem.
Biological control with beneficial pond bacteria can help mitigate large build-ups of sludge common in large water bodies. This happens due to runoff containing leaves, grass clippings, fertilizers, and animal waste entering the waterbody. When naturally occurring beneficial bacteria are added to the water body, they digest sediment materials and lower the organic matter in the water, and raise the dissolved oxygen to healthy levels.