Pond Restoration
Nutrient overload in Florida's stormwater ponds is a significant problem caused by excess nitrogen and phosphorus, leading to algal blooms (eutrophication), harm to aquatic life, and water quality degradation. Stormwater runoff from residential areas, fertilized lawns, pet waste, and leaky septic systems are major sources, driving the need for stricter regulations like the Clean Waterways Act to improve pond design and incorporate best management practices to reduce nutrient loads.
Nutrient overload (eutrophication) occurs when there's too much nitrogen and phosphorus in the water, usually from human activities, this excessive nutrient load stimulates a rapid overgrowth of algae, known as algal blooms. Prevention is a simple and effective method of lowering nutrient loads. If there are less nutrients to runoff into the stormwater area, then there is less potential for the pond to be overloaded.
One way to lower nutrient loads is through proper lawn fertilization, as over fertilization is one of the major causes of high concentrations of nutrients reaching water sources. Another method of prevention is ensuring that when mowing activities along the shore of the pond are taking place, the clippings are not blown into the pond. In addition to preventing high nutrient loads from approaching the stormwater area, the stormwater pond should have some sort of native vegetative plantings along the banks in the littoral zones.
Aquatic plants assist with prevention of erosion, nutrient management, and provide habitat for predatory insects which can prevent additional invertebrate pests from becoming a problem. One common pest that loves impaired water bodies are midge species.
Treatment Methods for Current Algal Problems
The function of stormwater ponds is primarily for pollution abatement and to provide water quality treatment for the runoff in the community or development. The pollutants specifically named by the permitting agencies (i.e., SFWMD) are the nutrients phosphorous and nitrogen. Due to this design, stormwater ponds are particularly prone to nutrient overload or eutrophication. Furthermore, elevated nutrient levels will cause excessive plant growth, including algal blooms.
The water quality treatment takes place in the water column from the control elevation down to a depth of approximately eight feet and primarily in the littoral zones. During water attenuation and biological processes, nutrients will decompose and settle on the pond bottom. However, when there are nutrient overload conditions, this process is inadequate to treat the elevated level of nutrients.
One method involves an aluminum sulfate treatment. Adding aluminum sulfate (alum) to the water, which binds with phosphorus and settles to the bottom, reducing the nutrient availability for algae growth. This will be followed up with a treatment with Green Clean Liquid 5.0. This chemical works by breaking down the cell walls of algae, destroying them from the inside out. This process releases oxygen into the water, and the product safely biodegrades.
The product is effective against various forms of algae, including plank tonic, filamentous, and matforming types. However, because the nature of the storm water management system being a changing environment in the pond, this is not a long-term solution. The second method is adding littoral plantings inside the pond to allow for nutrient uptake to reduce the amount of nutrient overload. This is not only recommended by the agency which permitted the stormwater system but is also proven to work.
