Lake Water Quality Testing

No matter the source, whether it be human activities or agricultural runoff, pollution can disturb aquatic life in numerous ways. Pollution generally reduces water quality and can reduce wildlife diversity, especially sensitive species and ecosystems.

Pesticides and fertilizers from urban and agricultural runoff and sewage seepage from groundwater enter lakes and raise nitrates and phosphates to undesirable levels in the water. This can lead to an increase in nutrients that cause nuisance plant and algae growth.

In addition, construction, agriculture, and urban activities can wash sediment into lakes, reducing water quality and water clarity. This sediment can be deadly to aquatic organisms, especially fish as it gets trapped in their gills, making it hard for them to breathe.

Industrial runoff also tends to contain heavy metals such as mercury and lead, which can work their way up the food chain. This can cause fish illness and death, and sicken the animals – and even the humans – that consume them. Likewise, atmospheric pollutants from industrial power generation or car exhaust can enter lakes as acid rain, which can also harm aquatic life.

When a lake is suffering from a harmful algal bloom, its recreational and aesthetic value is diminished due to the toxicity of the water, mats of unsightly algae floating on the surface, and the eye-watering smell that is released when cells begin to die. In fact, drinking water can be contaminated with foul taste and odor compounds.

The toxins produced during harmful algal blooms are dangerous to humans and pets. They can cause skin irritations, nausea, and gastrointestinal illness. When these toxins become airborne, recreational activities such as jet skiing and boating are an opportunity for exposure. Harmful algal blooms have been known to cause serious illness and even neurological diseases in humans, and often kill waterfowl and pets.

These blooms negatively impact the food web by reducing the number of edible microorganisms that other organisms need to survive. These organisms then starve and die off, leading to less food for fish and waterfowl. In addition, algal blooms often block sunlight from reaching the desirable plants and other organisms under the water’s surface, causing further food deficiencies.

One of the negative effects of eutrophication (nutrient pollution) and increased algal growth is the loss of oxygen available in the lake water – a state called anoxia. In addition to being deadly to fish, anoxic conditions can also be deadly to amphibians and other aquatic organisms. This may seem contradictory since algae produce oxygen, so how is the oxygen level lower?

While it is true that algae produce oxygen, it only does so if there is enough light. And eutrophication reduces the amount of light that penetrates the water. Algae are starved for light in eutrophic lakes. When the algae don’t have enough light, they no longer produce oxygen and begin to consume oxygen. When large algal blooms start to die, the bacterial decomposers further deplete the oxygen levels. Because of this, eutrophication can remove enough oxygen from the lake that it becomes a deadly underwater environment.