Like with any body of water, benefits do come with some risk. When it comes to health and safety, considerations will need to be made for both the critters within and outside of your pond.
Drowning
Children and animals are attracted to water and retention ponds offer ready access as they usually are not fenced in. These can be deep, with a steep drop-off point after a short aquatic shelf since they’re designed for maximum rainwater collection. Muddy bottoms and slippery sides can make it difficult for someone to escape.
Landowners generally have a duty to warn people of dangerous conditions on their property that might lead to reasonably foreseeable injuries. Signs that forbid trespassing, swimming, etc. can reduce your liability if someone were to be injured or drown. However, small children and animals can’t read, and these signs may not be helpful in these cases. If lots of small children are going to be in the area, like in the case of a residential or park-side addition, more steps will need to be taken to protect them. Live-saving equipment like poles or other floatation devices can provide observers with the tools to help should something happen.
Physical boundaries may also be helpful. Some reservoirs and ponds are built in such a way that a surrounding fence or barrier may help. Or, if the dam’s culverts are large enough for small children to slip through, grates can be installed to prevent this.
Mosquitos
Since mosquitos breed in any still water they can find, your retention ponds can become a nuisance to residential neighbors. Mosquito’s breeding habits can be interrupted by killing larvae or changing the quality of the water.
Mosquitos like to lay their eggs in warm, still water. Adding a waterfall, fountain, or aerator will enhance the pond's beauty while also getting the water moving, discouraging mosquitoes from hanging around. A professional aquatic service will be able to help you with installation that requires electric wiring or advanced pump systems.
A certified pesticide applicator can add a natural larvicide to your pond. Several products on the market are safe for people, pets, plants, and fish but effectively eradicate mosquito larvae without harmful chemicals -- although not all options are like this. Doing your research and asking questions of your local mosquito abatement authority will give you the most insight here.
Algae
In general, algae is essential for a healthy pond and ecosystem. However, a massive algae bloom can eat up all the available oxygen in your reservoir, killing fish and other plant life. The slimy green floating ‘lid’ associated with large amounts of algae is also generally unpleasant for those living nearby the pond.
Algae problems, like in the case of massive blooms and the resulting anaerobic conditions, usually occur due to ponds being neglected. While retention ponds require minimal maintenance, you can’t usually just dig a hole and then let the pond take care of itself. Healthy ponds require proper aeration, integrated pesticide management, and adequate pond weed control in order to maintain a healthy, functional level of algae.
Adding a waterfall, fountain, or aerator helps improve oxygen levels in the pond and can prevent algae blooms. Aeration can also cause a shift in the carbon dioxide levels within the pond and, in turn, can cause conditions that favor “good” algae over the undesirable blue green algae.
There are several available methods for algae control, including herbicides, bacteria and microbes, chemicals, UV sterilizers, and other additives. An aquatic management specialist that knows your area’s particular needs and qualities will be a huge help here.
