What Affects Water Quality in Lakes, Wetlands, & Ponds

If you see a lake that has muddy water, overgrown plants, and/or dead fish one of the main reasons why all those things are happening is because of poor water quality. Lakes, ponds, and other wetlands need frequent water testing and treatment in order to find the problem, analyze it, and treat it to improve the overall health of the wetland.

The water is a source of drinking water for the plants, livestock and other animals in the surrounding area. If a lake is affected with a certain bacteria or nutrition it can spread across the whole area and sometimes even get in the drinking water. There are certain things that lakes have to be tested for that have to be treated right away if there are traces in the water.

E. coli Bacteriarunoff of animal waste can put E. coli in lakes and ponds nearby

E. Coli is the waste from animals and/or humans. They can be entered into the water from run off of septic systems, or from wildlife or barns. In lakes and ponds that are used for recreation like swimming should have less than 126 colonies of E. Coli bacteria per 100 mL of water. E. Coli can be controlled by managing the septic tanks and runoff of animal waste nearby.


pH is the measure of how acidic or basic the water is. The right amount of acidity is important for the fish and plants the live in the water. The pH of a pond should range between 6.0 and 9.0. Freshwater fish will live best in water that has a pH around 7.0. If there is a lake or pond that has a low count of fish, it could be because the pH is below 6.0. There could be other reasons why there are a low amount of fish, and they only way to find out why is to do a water quality test. Treatment for low pH of a lake or pond is by applying limestone. The amount of limestone applied determines on the size of the body of water and level of pH.

Nitrate-Nitrogen and Total Phosphorus

If there is a lake that has increased growth of aquatic plants and algae than it may result in large concentrations of nitrogen and phosphorus. Large amounts of phosphorus can be from pollution of fertilizers or other nutrient-rich wastes like manures. The nutrients have to be reduced by redirecting the runoff or creating a buffer strip around the perimeter to keep aquatic plants and algae from over growing.

dissolved oxygen levels result in dead fish in a lake or wetlandDissolved Oxygen

The fish and plants use oxygen to sustain their lives and when there is a low amount of dissolved oxygen the fish will start to die. If there is a dissolved oxygen level below 6 mg/L it will start to affect the fish. The dissolved oxygen is measured by using either an expensive meter or a kit that is less expensive, but also less accurate. Warm water hold less dissolved oxygen than cold water. The problem of lack of dissolved oxygen can be fixed by controlling aquatic plants and algae growth or even adding aeration devices that increase dissolved oxygen.

Water quality testing is a service provided, among many other services, that Lake & Wetland Management provides. For more information on water quality testing visit here.