For many components in a community association, water is the number one enemy. From roof systems and parking structures to masonry and landscaping, water and water infiltration can seriously damage or degrade most reserve components. But of course, the weather cannot be controlled, and when it rains, it often does pour. So, when it comes to stormwater management, it is incredibly important that associations have a system in place to avoid flooding in any area. Enter: ponds!
There are two types of ponds that associations can utilize for stormwater management: detention and retention ponds. Detention ponds, which are usually dry, might also be called bio-retention basins, and are often funded with operating funds. Dry ponds are low, grassy areas that temporarily hold water after a storm, controlling the water flow to reduce flooding downstream and filtering out sediment and pollutants. Often noted by a PVC pipe sticking out of the ground, the outlet of dry ponds regulates the release of water, and maintenance is minimal – the filter material will need replacement. Other maintenance activities for dry ponds include mowing and the occasional cleaning of debris.
The second type of pond is a retention pond. This is what we imagine a pond to be, always holding water. Some properties may have a natural pond that existed before the association was even built, and because natural ponds have no infrastructure like inlets or outlets, there is not much maintenance to do, and the pond can be left alone if it is not a feature pond. Constructed stormwater management ponds are the most complex type of pond and require maintenance, upkeep, and even invasive testing.
During a reserve study, the specialist will not be diving into the pond, but they can still uncover various issues simply through observation. First, the water’s turbidity is observed, which refers to the number of particles suspended in the water. A pond would be considered turbid if it appears muddy or murky, especially past the first two feet of water. Besides looking unattractive, turbidity decreases the amount of light that can infiltrate the water and further reduces water quality.
Excessive algae also indicates water quality issues but generally means too many lawn care chemicals are reaching the water. Algae is fed by fertilizer, and its growth is accelerated by warm water temperatures, so in warmer climates or summer months, it is important to keep an eye out for algae blooms. Algae blooms are not just smelly and unsightly–they’re also toxic to humans and animals. In some cases, synthetic pond liners are an option for associations, as they prevent the exchange of nutrients from the bottom of the pond into the water and decrease the ability of algae to grow. These liners can offer good temporary control but do require periodic removal and cleaning of any growth.
Ponds that are turbid or those with excessive algae growth can be treated chemically, which generally comes from the operating budget. Aerators, which can be a reserve expense if warranted, are also a good solution for ponds with water quality issues. Aerators can look like fountains or a fishtank bubbler, circulate pond water and increase the amount of oxygen in the pond, which increases water quality and helps mitigate algae growth. The third issue reserve studies visually evaluate, which can be connected to both turbid water and algae growth, is shoreline erosion.
Shoreline erosion is one of the largest issues facing retention ponds. An eroding shoreline is an obvious issue, as the soil around the pond will be loose and collapse into the pond. As sediment fills the pond, water will become muddy looking, and stormwater storage capacity will decrease.
There are numerous options available to associations when choosing an erosion control method, and a buffer zone is one of the best. Buffer zones, generally three to five feet wide, are deep-rooted wildflower plantings and grasses. Deep roots stabilize the shoreline, keeping the ground where it is supposed to be – on the shore. These plantings help filter out any lawn care chemicals before they reach the pond and can also keep pesky ducks and geese out of the water, which can be especially beneficial in areas with wetlands. However, not all deep-rooted plants are suitable for use as erosion control.
Invasive species with aggressive growth habits can accumulate sediment and spread too far, filling the pond, and decreasing its stormwater capacity. These plants tend to take over any other beneficial vegetation growing around the pond and should be removed to keep the pond in working order. While some invasive species could be removed without a professional, it is recommended to contract this work to ensure the plants are completely removed and have no opportunity to re-grow. 
In areas such as Florida, where a desire for closely mowed lawns is more common, erosion becomes a greater risk. The constant mowing can destabilize the soil, especially when water levels fluctuate. In these cases, landscapers may employ spot erosion control methods, such as laying sod, but these solutions can be ineffective when the water levels rise or fall dramatically.
Larger ponds with waves or those with steep shorelines may experience increased erosion that can be remedied with riprap. Riprap, commonly seen on a larger scale along lakes, rivers, and bridges, is a barrier made of natural-looking rock or stone that protects shorelines from wave and current damage as well as keeping the shoreline in place.
Geosocks offer another solution for shoreline stabilization. These are long, sock-like tubes that can be staked along the shoreline to provide a secure base, holding the bank in place where it is most needed. In some cases, more permanent solutions, like retaining walls or bulkheads, may be necessary, especially for areas with severe erosion or steep banks. Retaining structures such as concrete seawalls with driven piles offer a more long-term, low-maintenance solution but can be cost-prohibitive unless there is a clear need due to the severity of the erosion.
While the gradual buildup of debris such as leaves, branches, and silt are natural, it may eventually change the topography of the pond and decrease the pond’s ability to store stormwater. Silt generally accumulates at inlets, outlets, and areas of shoreline erosion, and its accumulation alters both the functionality and quality of the pond and pond water. Sediment removal is the necessary and optimal route to take when functionality is at stake, though it is the most capital-intensive method of pond management. Sediment removal can be executed with clamshells, draglines, and suction pipelines and is called dredging.
Because visual inspections alone cannot reveal the amount of accumulated silt, especially in larger ponds, the actual volume of silt to remove may be dependent on a more invasive analysis known as bathymetric surveys.
Bathymetric surveys establish a database about the depth of the pond in various locations. Over time, these surveys can be compared to figure out where sediment buildup is most prominent and needs removal, and more importantly, they determine the capacity that the pond still has. This procedure requires multiple site visits, and we recommend contracting a local engineer for these periodic surveys. Future reserve studies or reserve study updates can then incorporate the predicted expenditures for removal based on the survey results.
Removal costs can vary significantly based on the equipment used, the quantity of sediment removed, and the method of disposal. However, dredging using any method will be costly. Because this process is capital-intensive, reserve studies aim to draw attention to this large piece of infrastructure that many associations may not even know they should be paying attention to.
While there is not much in the way of pond maintenance activities, there are a few things you can do to keep yours in tip-top shape. To ensure proper water flow, inlet and outlet structures should be checked regularly, especially after heavy rainfall. Any blockages such as trash, vegetation, or other debris should be removed, and if the structure is damaged or collapsed, this should be noted and remediated with a professional contractor.
Ponds with buffer zones, particularly in areas with wetlands, may need occasional controlled burns, which should be done by a professional and can be included as a reserve expense. Bathymetric surveys and periodic erosion control can also be included as a reserve expense if warranted, and this can be discussed with your reserve specialist.
Shoreline erosion and sediment accumulation should be inspected and remediated annually, and chemical treatment or aeration should be considered for ponds with excessive algae growth or algae blooms.
While your association’s pond may stay back-of-mind, as maintenance is fairly infrequent and it isn’t a component that needs replacement, it’s important to remember that dredging is an expensive project. So, if your community’s retention pond experiences erosion, algae blooms, or has consistently murky water, these are important issues to note. Reserve studies can take future surveys and dredging into consideration to prepare your association for these projects, even if they are years away. After all, you don’t want to wait until your property floods before finding a solution.
