AS SEEN IN Culpeper Soil & Water Conservation District – Views From the Foothills, May 2014: Written by Industry Expert Shannon Junior, Aquatic Ecologist
The last decade has brought major changes to the pond and lake management industry. The owner of every privately maintained pond, lake or stormwater BMP has the responsibility of managing the structural, functional, and aesthetic integrity of their waterbody. The primary ongoing maintenance issue associated with these aquatic resources is typically the prevention and control of nuisance aquatic vegetation. Historically, a baseline management plan for an impaired pond or lake would include frequent and repetitive herbicide applications for the control of unwanted algae and weeds. However, in recent years the regulatory environment has become more constraining. The National Pollutant Discharge Elimination System (NPDES) permit for aquatic herbicide applications went into effect late in 2011, and requires that Integrated Pest Management (IPM) strategies are considered prior to the decision to apply herbicides for nuisance vegetation control. In addition, the public has become warier of herbicides, and pond owners have been requesting more environmentally friendly strategies for management.
As ponds and lakes age, they retain sediment, nutrients, and other pollutants. As these substances accumulate over time, the water quality
in the resources becomes impaired, and pond algae
and nuisance vegetation growth become more prevalent and problematic. Treating blooms of algae and weeds with an herbicide provides short-term symptomatic relief, but does not address the underlying issue of nutrient enrichment that is ultimately causing the problem. In order to provide more long-term, sustainable solutions, new management strategies involve an integrated approach that includes the implementation of multiple non-herbicide methods to improve water quality and reduce the conditions that cause nuisance vegetation blooms.
Identification of the individual species of algae that are present in a pond and the water quality parameters and sediment characteristics of the waterbody are critical in the development of site-specific management strategies. Cyanobacteria (aka blue-green algae) blooms have become increasingly common in ponds in our area and can be potentially harmful to humans, pets, and wildlife. The prevalence of these blooms can be directly controlled by phosphorus reduction
, which can be achieved through the application of a new product that has a high affinity to permanently bond with phosphorus in the water column and sediment. The amount of product required and the application schedule would be based on the results of the laboratory analysis and budgetary considerations.
and diffused air aerations systems have become commonplace in many ponds and lakes, and remain one of the most cost-effective strategies for long-term water quality improvement. In general, aeration encourages the growth of beneficial bacteria, which compete with algae for excess nutrients and also break down decaying organic matter. The technology of fountains and aerators is improving, and the systems are becoming more effective and less expensive to install and operate. New and improved LED lighting options for fountains consume a fraction of the electricity of traditional halogen bulbs, and also last for many years, eliminating the need for frequent bulb changes. A solar aeration system
that is more affordable than those currently available is anticipated to be released to the market in the spring of 2014.
We can expect the role of Integrated Pest Management strategies in pond and lake management to continue to expand. However, for certain invasive species
and in ponds with extremely compromised water quality, the use of herbicides may always be required. Fortunately, new products are being developed with improved delivery formulations, synergistic active ingredients, and built-in water quality enhancers to make the use of herbicides safer, more effective, and more sustainable in the future.