Stormwater ponds exist in communities and commercial properties everywhere. They are designed to capture excess water runoff from the land and impervious surfaces surrounding them. In 2009, the small state of Maryland had approximately 18,000 wet stormwater ponds cover- ing 200,000 acres. These bodies of water generally contain high levels of nutrients and other pollutants.
In some instances, stormwater ponds are simply a collection vessel for water that is void of plant material. This is because the surround- ing plants are mowed to the water’s edge and any volunteer plants are treated with herbicides and subject to recurring or persistent algae blooms. Algae can become toxic if incoming nutrient levels are so high that regular algaecide treatments become ineffective at controlling the problem.
Other ponds become sanctuaries for weeds like Phragmites and Cattails, which establish themselves via seeds blown in with the wind. When left untreated, they can become invasive. Both plants are relatively unattractive and have a tendency to collect windblown trash, rendering them very unsightly.
One of the biggest problems with stormwater ponds is sediment runoff, which carries much of the unwanted pollutants from excess fertilizer, animal waste and organic matter into the pond. This is problematic not only because the pollutants contribute to high nutrient levels, but also because soil sediments collect in the pond bottom, reducing the depth of the pond over time. Shallower water also encourages nuisance algae growth that can form dense mats and become ugly. In some cases the sediments will need to be dredged, and it can be difficult to find a location willing to take such nutrient-laden sediments.
Educating landowners is critical to the process of storm- water pond improvement. A lot of the excess nutrients come from fertilizer runoff. More often than not, topsoil is harvested from construction sites prior to building. This generally leaves behind a soil that is depleted of organic matter and full of clay. Applied chemical fertilizers don’t stand a chance at being absorbed into the soil; during rain events a majority is washed off into the stormwater pond.
A change of thinking is necessary, with the emphasis being placed on amending soil rather than repeated applications of fertilizer. Improved soil leads to better nutrient uptake by lawns and gardens, thereby reducing the amount that ends up in stormwater ponds.
Fowling the WaterGeese and ducks are lovely to look at, but they contribute heavily to the amount of nutrients in a pond. Large populations can generate enough waste to severely debilitate a water body through nutrient loading. Discouraging their presence will improve water quality, and a heavily planted shoreline will eliminate the feeling of safe harbor for the birds. Wildfowl are hesitant to penetrate thick vegetation for fear that predators may be lurking, so eliminating easy access to the pond is an excellent deterrent.
Because water attracts wildlife, stormwater ponds can also become home to insects, fish, frogs, birds and various other living things in abundance. The ecological diversity can add interest, with birds nesting, frogs croaking and bees and butterflies in flight. This often contributes to the ponds becoming a focal point to the surrounding homes and businesses — as long as they are properly maintained.
A recent study indicates that residents are inclined to believe their property values are 15 to 25 percent higher if they are near a well-managed pond. It would be important to consider what they might perceive the reduction in property value to be if the pond is unsightly due to weed and algae growth and has a rancid odor. In the late ‘80s, Ruppert Landscape compared two apartment complexes. Each had a stormwater pond, and they shared the same entrance and were of the same design. One pond was beautified and the other remained a traditional stormwater pond. The complex with the beautified pond had a waiting list while the other had consistent vacancies.
Well-maintained ponds will also illicit community involvement. Residents will be more inclined to make visual inspections and make reports to grounds committee members for repairs and improvements. Based on experience, they will request new plants and encourage new projects.
Aquatic and moisture-loving plants, trees and shrubs combine to create background and surface reflections. Colorful hybrid water lilies are the best choice for the shallow edge of the pond. They provide shade and surface coverage without taking over the pond, and they add season-long color.
Laying Down a SolutionThe best way to establish an effective shoreline planting is Wetland Carpets. These are woven, biodegradable coir (coconut) fiber blankets, three feet by 15 feet in size, that are pre-planted to allow sufficient time for the plants to develop an ample root system.
Pre-planted Wetland Carpets are superior to direct shoreline planting for several reasons. First, wildfowl are curious by nature and have a habit of following behind the planting crew to sample what has been installed when planting standard plugs. Because the plants in a Wetland Carpet are well-rooted in the coir, geese and ducks have less of an opportunity to dislodge the plants before they become established in their new homes. The plants establish quickly because they are already rooted, so it gives them a competitive advantage.
Cattail and Phragmites seedlings germinate on the moist banks and not in the water. The added benefit of the Wetland Carpet is that the unwanted seedlings cannot penetrate the thickness of the coir, so they don’t have the ability to re-establish before the preferred plant material fills in. Any seedlings that pop up on the soil side of the Carpet can be spot-treated with herbicide to prevent their return.
Plant collections can be custom-grown to suit the location, water depths and native requirements. Plants with the greatest nutrient uptake ability can be combined with other favorable plant material to maximize the benefits of the planted shoreline. In some instances beautification is the primary goal, but regardless of the initial goal, adding a well-planted perimeter to any water body will be an asset. Shoreline planting will help to improve defunct stormwater ponds, reduce nutrient loads, reduce dangerous erosion, improve water quality and clarity, improve ecological diversity, deter some unwanted residents like geese, increase property values and improve your bottom line.