It is a sad fact that ponds and lakes begin to die on the day that their construction is completed. When flowing water is captured behind a dam embankment, sediment, nutrients, and other pollutants settle to the bottom of the basin and are left behind in the pond, and the cleaner water leaves through the outlet structure. So the fate of the stormwater management ponds in our communities is that they become impaired over time because of their function to filter runoff and protect downstream water resources. This process of nutrient accumulation and pond aging is known as eutrophication, and eutrophic ponds can become a maintenance nightmare.
Unfortunately, ponds and lakes that become over enriched with nutrients are more susceptible to cyanobacteria and nuisance algae blooms, surface biofilms, excessive submersed plant growth, and related oxygen depletion. That “ugly pond” in your community is likely suffering from a severe case of nutrient pollution. Mitigating the effects of nutrient loading is the key factor in successful lake management programs, with phosphorus being the primary concern.
Integrated Pest Management strategies for nuisance aquatic vegetation and algae control include preventive approaches to minimize the amount of nutrients and sediment entering waterbodies. Whenever possible, it is recommended to integrate sustainable, proactive practices into long-term pond management plans in order to improve water quality and minimize the quantity of pesticides required to maintain healthy and attractive ponds and lakes. Unfortunately, though, many of the nutrient inputs to stormwater ponds come from outside of the community and cannot be controlled. And while preventive strategies are widely implemented, they are inadequate to restore ponds that are already impaired. Physical removal of unconsolidated sediment and the associated nutrients (i.e., dredging) is the most direct mitigation strategy and will ultimately be required for every stormwater pond, although it is a major process and can be cost-prohibitive.
There is a new technology available for pond restoration that results in the permanent inactivation of phosphorus. SOLitude was fortunate to be among the first companies in the U.S. to have the opportunity to use an innovative phosphorus binding product called Phoslock. When Phoslock is applied to a pond, phosphorus is permanently removed from the water column, and improves water quality by resetting the eutrophication clock. The product is completely safe for use in the aquatic environment, with no adverse effects on fish, macroinvertebrates, or other wildlife.
In order to implement the most effective phosphorus mitigation strategy with Phoslock, laboratory testing is recommended to assess the water quality entering and within the pond, including the phosphorus levels in both the water column and the sediment. But even when laboratory test results are not available, the product can be applied at a moderate baseline rate on an annual basis as part of an ongoing pond management program. In order to evaluate the effectiveness of this strategy, we applied Phoslock to 100 ponds in 2012, and developed an objective rating system to quantify the results.
Since laboratory test results were not available for these ponds, we instead assessed the management inputs (i.e., labor hours and product quantities) required after the Phoslock applications compared to historical programs as an indicator of phosphorus, tropic status (i.e., ecological age) and water quality. Our assumption was that more eutrophic ponds with poor water quality would require more management inputs compared to ponds with better water quality.
For ponds where there was no obvious difference in water quality and management inputs after the Phoslock application, we used a rating of “Neutral.” Ponds where there was an improvement in water quality and reduction in management inputs were rated as “Positive,” and ponds with a significant improvement in water quality and a 50% or greater reduction management inputs were rated as “Excellent.”
We observed Positive to Excellent results in 83% of the ponds (49% Excellent, 34% Positive) and the remaining 17% were rated as Neutral. As an example of improving the trophic status and water quality over time with repeated applications of the product, one pond had a 50% reduction in management inputs in 2012, an 85% reduction in 2013 and a 99% reduction in 2014 compared to the 2011 program.
Moving forward, we will continue to integrate Phoslock as part of our management programs to reduce phosphorus, improve the trophic status and ultimately improve water quality in our clients’ ponds and lakes. Although Phoslock is not always less costly than herbicides from a short-term financial standpoint, we feel that a more environmentally sustainable strategy is the best value that we can provide for a long-term pond management program.
Visit our online store to order Phoslock or call 888.840.LAKE.
In support of our belief that lakes and ponds are a precious natural resource requiring protection, SOLitude is committed to providing sustainable and renewable solutions that maintain ecological balance in the workplace and beyond.
When you partner with SOLitude, a dedicated field technician visits your lake or pond twice a month, leveraging extensive knowledge and training to carefully maintain ecological balance and preserve the appearance of your aquatic property.
Utilizing the latest GPS aquatic mapping technology and our own proprietary lake and pond management software, the experts at SOLitude collect all the data necessary to provide comprehensive analysis and in-depth solutions.