Naturally occurring processes in ponds and lakes

What is Eutrophication?

Eutrophication is a naturally occurring process in ponds and lakes. Taking a proactive approach to lake management will ensure the health and beauty of your pond or lake for years to come.

Example of an eutrophic lake

Example of an eutrophic lake

Water quality is obviously the most important factor to consider when determining the health of a pond or lake. The vast majority of recreational ponds and lakes are bombarded with nutrients from various sources. This process, known as Eutrophication, is responsible for the excessive growth of algae and aquatic plants as well as the buildup of organic sludge and offensive odors.

These ponds and lakes are typically very productive and can sustain large populations of fish and other aquatic life. However, they are more susceptible to oxygen crashes and fish kills.

All lakes age the same way – they begin as Oligotrophic Lakes, and gradually age to become Eutrophic Lakes. Allowing nutrients to accumulate in our lakes from agriculture, fertilizers, streets, sewage, and storm drains speeds up this process.

 

Oligotrophic Lakes

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Oligotrophic Lakes are those that are generally clear, deep, have low primary production, and are clean pristine lakes. The food chain in oligotrophic lakes is very structured and is capable of sustaining a fishery of large game fish. These lakes tend to be the most aesthetically pleasing of lakes due to their clear blue water. In oligotrophic lakes, there is usually a very high measure of water clarity reading (in relation to the depth of the lake) and low phosphorus and chlorophyll readings.

 

Mesotrophic Lakes

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Mesotrophic lakes are in the boundary between oligotrophic lakes and eutrophic lakes. They have more nutrients and production than the oligotrophic lakes, but not nearly as much as eutrophic lakes. Mesotrophic lakes have some accumulated organic matter on the bottom of the lake, as well as an occasional algae bloom at the surface. They are usually good lakes for fishing, as they are able to support a wide variety of fish. In the late summer, the hypolimnion can become depleted of oxygen, which limits cold water fish and causes phosphorus cycling from the sediments. Mesotrophic Lakes have water clarity, phosphorus, and chlorophyll readings between those of eutrophic and oligotrophic lakes.

 

Eutrophic Lakes

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Eutrophic Lakes are the most productive lakes, and thus support a very large biomass. These lakes are normally weedy and subject to frequent algae blooms yearly. There is often a large amount of accumulated organic matter on the bottom of the lake. Eutrophic lakes support large fish populations, however, rough fish, like carp, are common in these lakes. Eutrophic lakes are susceptible to oxygen depletion in the hypolimnion, and shallow eutrophic lakes may be vulnerable to winterkill situations. Eutrophic lakes have low water clarity readings in relation to the depth of the lake and high phosphorus and chlorophyll readings. Most problems occur in Eutrophic Lakes. Nearly all urban lakes are now Eutrophic in nature.