There are many factors that influence your pond: its size and shape, depth, watershed area, land uses around the pond, fish and plant species in the pond, soil types, groundwater chemistry… the list goes on. It should come as no surprise then, that relying on only one management technique will seldom produce desired results. But this is exactly what many pond managers do.
Let’s look at a golf course pond that is only managed by chemically treating nuisance algae growth. The greens are fertilized and the ponds are mowed to the water’s edge. Fertilizer runs directly in to the pond, fueling an algae bloom. The pond manager sprays algaecide to kill the algae, but it quickly re-grows. The process is repeated again and again. Over time, these chemical treatments only allow resistant species of algae to survive. The pond manager then uses more potent chemicals, but these also kill the rooted plants that were competing with algae for the available nutrients. Without this competition, algae blooms are worse than ever. As time goes by, even the more potent chemical treatments become ineffective as resistant algae species predominate. The end result is an algae-choked, odorous, stagnant pond that seems unmanageable.
We have learned that the best way to avoid the scenario described above is to use an integrated approach to pond management. An integrated approach means using multiple techniques to manage a problem. In the case of managing algae in your pond, it starts with limiting nutrient inputs. This can mean avoiding lawn fertilizers and maintaining buffer strips. It can include application of polymers that bind to phosphorus. It may also include introducing competition for available nutrients by applying bacteria and enzyme products, and planting emergent plants. Employing an aeration system allows beneficial bacteria to proliferate, and eliminates the stagnation that allows algae to thrive. Applying pond dye physically blocks sunlight that algae requires. An integrated approach can also mean using chemical algaecides, but since they will be needed much less frequently, the problem with resistance and non-target impacts are much less likely to occur.
Article originally published in the Cason & Associates Spring 2010 newsletter