The proper balance of nutrients in an aquatic ecosystem is vital for aquatic life, health and environmental safety. Controlling nitrogen and phosphorous which often occur in excess in bodies of water surrounded by fertilized vegetation, accumulated organic materials and abundant human activity is particularly important. This is often because fertilizers and excess organic material contain excess nitrogen and phosphorous to increase plants growth potential. Consequently, these chemicals increase the growth potential of plants and, more commonly, algae in your pond. This can cause algal blooms, or eutrophication, which are masses of algae that use up the excess nutrients. These large mats of algae block surface light from reaching other vegetation below the surface. Then, when these large masses of algae colonies die off and are decomposed the bacteria use up much of the oxygen in the lake, leaving dissolved oxygen at a depleted level called hypoxia, which can lead to diseased fish and dead zones of uninhabitable waters.
Eutrophic waters with bacterial build up can be harmful if people come into contact with them. Toxins can also be consumed by aquatic organisms and kill larger fish and other predators as it moves through the food chain. In some cases nutrients can seep into groundwater, which is the source of drinking water for many people, and can be harmful even at low levels. Infants are especially vulnerable to nitrates in groundwater. Symptoms of eutrophication to watch out for include; poor water clarity, algae that recurs quickly, shoreline odors and sick and dying fish.
Needless to say it is important to limit these effects on your pond. There are many ways to reduce phosphorus and nitrogen from entering your pond, as well as limit their effects on your aquatic ecosystem. On the front end there are a few things you can do to reduce the abundance of these chemicals near your pond. A reduction in the level of fertilizers in the watershed to your body of water will reduce runoff of excess nutrients. If you can’t reduce your use of fertilizers, using them in better ways will also reduce runoff. Make sure to apply the suggested amount of fertilizers at the correct time of year and use the proper application methods. Doing this will not only reduce runoff of excess nutrients, but also ensure that you are giving your plants a better chance to use those nutrients. Using non-phosphorus based fertilizer on lawns and gardens can also help. On your fertilizer label look for a nitrate-phosphorus-potassium number set, such as 22-0-15, the middle number should be zero. Properly disposing of grass clippings and other organic materials similarly will reduce the excess nutrients entering the water, as well as keeping them off of streets and other places that they are likely to runoff into waterways.
Your second line of defense is a buffer of deep rooted plants such as flowers, shrubs and trees at the edge of fertilized fields and around the border of your pond that will soak up any nutrient runoff before it has the chance to reach your lake or pond. Thick vegetation on the border of your pond also has the added benefit of restricting the access of wildlife to the shores of your pond and reducing their waste in your pond. Another way to filter out nutrients is with a sedimentation pond. This is a shallow pool at the inlet of the pond where water will momentarily remain stagnant and allow sediment and nutrients to settle before the water flows into the main body. In addition, planting cover crops such as certain grasses, grains or clovers in with your other plants can help recycle excess nutrients and reduce soil erosion.
Once the excess nutrients have entered your pond or lake there are still a few things you can do to limit their effect on your aquatic ecosystem and dissolved oxygen levels. Installing and maintaining an aeration system will stabilize dissolved oxygen levels by continuously flowing air into the water encouraging healthy levels of many dissolved chemicals, especially oxygen. In addition to aeration chemicals such as Alum, PhosLock, and Polyaluminum chloride can bind to excess chemicals, making them functionally unusable to algae and reducing their impact on your aquatic ecosystem. As a last resort, if excess sediment and nutrients have accumulated in your pond, dredging and hydro-ranking are both options to remove excess matter and regain previous water depths.
Keep in mind that it is most preferable and easiest to solve the problem nearest to the source, and whatever aquatic management practices you use to prevent eutrophication, it is important to stay consistent and diligent with your strategies to make sure they are effective.
“15 Ways to Reduce Nutrients in Lakes and Streams.” Minnesota Pollution Control Agency, 13 Sept. 2017, www.pca.state.mn.us/water/15-ways-reduce-nutrients-lakes-and-streams.
“Control Lake Algae through Nutrient Reduction | Aquatic Systems.” Aquatic Systems Lake Management, www.aquaticsystems.com/florida-lake-management-services/restoration-and-nutrient-reduction/.
Management, SOLitude Lake. “How Can There Be ‘Too Many Pond Nutrients’?” SOLitude Lake Management: Full-Service Lake And Pond Management, www.solitudelakemanagement.com/blog/how-can-there-be-too-many-pond-nutrients.
Perlman, Howard, and USGS. “Phosphorus and Water.” Livestock Water Use, the USGS Water Science School, water.usgs.gov/edu/phosphorus.html.
“Pond Ecology.” Penn State Extension, extension.psu.edu/pond-ecology.
“The Effects: Environment.” EPA, Environmental Protection Agency, 7 Apr. 2017, www.epa.gov/nutrientpollution/effects-environment.
“The Problem.” EPA, Environmental Protection Agency, 10 Mar. 2017, www.epa.gov/nutrientpollution/problem.
“The Sources and Solutions: Agriculture.” EPA, Environmental Protection Agency, 10 Mar. 2017, www.epa.gov/nutrientpollution/sources-and-solutions-agriculture.
US Department of Commerce, and National Oceanic and Atmospheric Administration. “What Is Nutrient Pollution?” NOAA’s National Ocean Service, 1 Sept. 2009, oceanservice.noaa.gov/facts/nutpollution.html.