Other than regulating water flow, retention ponds also help purify water. A variety of plants surround ponds. Other than functioning as aesthetic decoration, these plants also block pollutants from entering the pond and absorbing them with their roots. Vegetation also stabilizes the banks and prevents erosion. Additionally, sediments can settle to the bottom over time, instead of directly flowing into the main river channel. Some ponds also serve as a habitat for wildlife and allow water to percolate into the ground to recharge aquifers. 

A distinctive feature of retention ponds is that they always hold water, unlike their counterpart - detention ponds, which also store water but eventually empty it out to other downstream water bodies. Detention ponds have an outlet pipe close to the bottom of the pond to drain water. While retention ponds also have an outlet, it is smaller and located higher up the banks. This controls the amount of water that can permanently remain in the pond. The size of the outlet pipe also gives control over the outflow of water. 

Holding water permanently is simultaneously an advantage and a disadvantage of retention ponds. The body of water is a habitat for a diverse range of flora and fauna, such as amphibians, birds, fish, and geese. Retention ponds can store water in case of drought and allow recreational activities for nearby residents. However, the still body of water has a risk of becoming a mosquito breeding ground. A retention pond also requires a large amount of land to be built in order to function properly, which might pose a challenge for areas and neighborhoods that are densely populated. 

Regular maintenance is vital for retention ponds. As sedimentation occurs, a layer of sand and other insoluble particles build up and form a layer of sludge at the bottom of the pond. This may reduce the capacity of the pond. Inlet and outlet pipes are also prone to clogging and have to be checked regularly. Washed-up vegetation, rocks, and dirt need to be cleared. Algae growth and soil erosion also need to be monitored to keep the water clean. In other words, retention ponds must be monitored in order to assure that they do not have a negative effect on water quality, defeating their purpose. 

Retention ponds are common, yet remain unnoticed by most. As our climate changes, it is essential to learn to adapt to emerging problems with new technologies. Retention ponds bring benefits of flood control, water purification, and biodiversity. However, like all man-made structures, they also require regular maintenance for appropriate functioning. Fluvial systems are complex and are a combination of natural and artificial elements - winding rivers, dams, and wetlands. These elements are gears in a system much larger than ours, and man-made infrastructure like retention ponds is just one of many tools that can help protect our environment and build a sustainable future.