La Lake

La Lake

Lake Description

La Lake is a 52-acre, shallow lake located in Woodbury, MN. The lake receives contributions from a small sub-watershed of 64 acres, of which 3.5 are impervious. La Lake is mostly surrounded by developed land, and La Lake Park to its southern shore.

Lake Details

Water Quality in La Lake

La Lake is a clear and shallow lake, reaching a maximum depth of 3 meters. Water clarity is determined by measuring its transparency or turbidity, which can be tested with a Secchi disk. A Secchi disk is a black and white disk that is dropped into the water attached to a line with meter marks to measure the depth of clarity. In La Lake, the average Secchi depth is 1.9 meters, which exceeds the Minnesota State standards of 1.0 meters. 

Water quality can also be determined by analyzing total phosphorus (TP) and chlorophyll a. TP measures all forms of phosphorus present in the water, including dissolved and particulate forms. Phosphorus comes from several sources, natural and human-related. Naturally, phosphorus typically comes from the decomposition of organic materials, like aquatic plants and animals, and it can also come from soils. Phosphorus can also come from agricultural runoff, stormwater treatment, and home fertilizers. When there is too much phosphorus in water, it can result in eutrophication. This is the process by which a waterbody becomes overloaded with nutrients, primarily phosphorus and nitrogen, that which excessive growth of algal blooms. This can lead to a depletion of oxygen, harming aquatic life such as plants, animals, and macro-invertebrates, at which point the lake becomes biologically dead. 

In La Lake, the average TP concentration is 71 μg/L), just exceeding the shallow lake standard of 60 μg/L). 

Chlorophyll a is another indicator of water quality. Chlorophyll is a measure of the amount of algae and cyanobacteria growing in a waterbody. Cyanobacteria, more commonly known as Blue-green algae, is a harmful form of bacteria and in fact not an algae at all. Cyanobacteria thrive in warm, nutrient-rich waters. These conditions occur as temperatures increase, and nutrients like nitrogen and phosphorus are present in the water. Certain varieties of blue-green algae can produce toxins that are linked to illness in humans and animals.

Monitoring Data

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