Preventing Excessive Aquatic Plant and Algae Growth

(upbeat instrumental music) [DANIELLE RHEA] Over half of Pennsylvania pond owners surveyed report nuisance levels of algae and aquatic plants. Most ponds don't start out that way, but over time, the accumulation of nutrients and sediment creates an ideal ecosystem for algae and other aquatic plants. Ponds act as water catchments for the land surrounding them. Runoff flowing into ponds can also carry pollutants, such as nutrients and sediment. Increasing levels of sediment and nutrients can lead to eutrophication. Eutrophication is when a body of water receives excess amounts of nutrients, particularly nitrogen and phosphorus, thereby promoting the excessive growth of aquatic plants and algae. While the eutrophication of ponds is part of the natural aging process, many human activities can accelerate it. Nearby fertilizer applications, animal manure, septic systems, erosion, urban runoff, and wildlife all can add significant amounts of nitrogen and phosphorus to a pond, causing algae and aquatic plants to grow. Erosion can further accelerate pond aging by delivering excess sediment to the pond. As sediment accumulates, the pond depth will diminish, effectively increasing the proportion of water that sunlight is able to reach. Preventing overabundant aquatic plants and algae starts with preventing nutrients and sediment from entering the pond. Just as nitrogen and phosphorus in fertilizers and manure stimulate the growth of lawns and crops, they will also stimulate the growth of aquatic plants. Plants can only use a limited amount of nutrients in a growing season, so it is important to apply fertilizers and manure based on guidance provided by a soil test. Keeping fertilizer and manure applications away from the edge of the pond also reduces the likelihood of them washing directly into the pond water. The Pennsylvania Fertilizer Law requires a 15-foot setback when applying fertilizers to lawns. And manure management regulations require setbacks ranging from 35 feet up to 150 feet in certain circumstances. Another way to prevent nutrients and sediment from washing into the pond is by establishing a vegetative buffer around the perimeter of the pond, as well as the springs and streams that feed the pond, as you can see here. By maintaining perennial vegetation, including tall grasses, wildflowers, shrubs, and trees, the land adjacent to the pond can capture nutrients before they can enter the pond. Generally, a minimum of 35 feet is recommended for capturing nitrogen, but a wider buffer is more effective for filtering out phosphorus and sediment. However, do not allow trees to grow on the dam to prevent potential problems with leaks. Sources of nutrients from nearby animals should also be controlled. Use fencing to prevent or limit farm animals from directly accessing the pond. Manure storage facilities and temporary stacks should be located at least 100 feet away from the pond and away from concentrated water flow. Divert runoff from barnyards and pastures away from the pond. In some cases, wildlife, such as Canada geese, add significant nutrients, particularly phosphorus, to a pond. Often, establishing a buffer strip is enough to discourage a large flock from residing at a pond. However, fencing, barriers, chemical deterrents, oiling eggs, and hunting may be other options for controlling nuisance goose populations. Human waste can also create issues for ponds. The Pennsylvania Department of Environmental Protection requires that septic tanks, dosing tanks, and lift pumps be at least 25 feet from a pond, and septic system drain fields must be at least 50 feet away. Septic tanks should also be pumped every three years to prevent the discharge of nutrient-laden water into the landscape. A simple way to prevent sediment pollution is to ensure that the soil uphill of a pond is always covered by a growing plant. You can create a small sediment pond near the inlet of the main pond to slow water so that sediment can settle before reaching the main pond. Controlling nutrient and sediment pollution can have a dramatic long-term effect in reducing aquatic plant growth in your pond. Consider the potential sources of nutrient and sediment pollution near your pond and think about the steps you can take to reduce their impact. Sometimes starting with small steps, like observing fertilizer setbacks or establishing a small vegetative buffer, can have big benefits.