Wirth Lake is located in the 759-acre Theodore Wirth Park, the largest regional park in the system. The lake has a beach, fishing pier and boardwalks. Paths for walking and biking, volleyball courts, a playground and picnic facilities make this lake a popular destination. Wirth has excellent aesthetic and recreational ratings and good water clarity.

Water Clarity

Recent Secchi Disk Readings


September 27, 2017

Secchi Depth (feet): 7.9

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About Secchi Disk Readings

secchi diagram

To measure water transparency with a Secchi disk, the disk is lowered from the shaded side of a boat until it cannot be seen. The depth of the water is recorded at the point where the disk reappears upon raising it from its original depth beyond visibility. It is important to remember that the Secchi measurement is a simple, approximate measurement of water clarity and can be influenced by various factors such as time of day, reader's eyesight, water color and suspended particles in the water. Therefore, Secchi disk readings should be used as a comparative tool to determine trends between lakes and over time.

  • Increased water clarity may be due to reduced nutrient inputs, seasonal algal cycles, decreased sediment inputs, and zooplankton grazing on algae.
  • Decreased water clarity may be due to large algal blooms, increased soil erosion inputs, wind circulation of sediments and nutrients, stormwater inputs, or a decrease in zooplankton.

Secchi readings for the lakes are done during the regular lake sampling schedule, with some lakes sampled every other year.

Beaches

Recent Beach Status

Wirth Lake Beach

Testing has ended for 2017
and will resume June 2018

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What does the E. coli level mean?


Beach Water Quality Factors

Each summer, thousands visit our City lakes and enjoy a refreshing swim at our many swimming beaches. To ensure a healthy and enjoyable experience for these swimmers, we monitor the water at the public beaches for E. coli, bacteria that can be an indication of health risks for swimmers.

Beaches close if a water sample does not meet the State of Minnesota’s guidelines. A beach reopens when testing reveals that levels are within guidelines. The test for E. coli takes 24 hours, and results are posted early afternoon the day after we sample a beach.  The closing of a Minneapolis beach is rare, and in most cases the beach will re-open quickly.

Bacteria Levels Rise with Rainfall

High bacteria levels generally occur immediately after rain events in Minneapolis. Here's what you should be aware of regarding bacteria levels:

  • Pick up after your Pet: Increased bacteria levels predominantly come from waterfowl and pet wastes in yards, streets and parks that wash into lakes either directly or through the storm sewers as the result of a heavy rain.
  • Avoid Swimming after a Rainfall:  Elevated bacterial levels in lakes generally return to normal levels within 48 hours of a rainfall.
  • Swim Healthy:  Avoid swimming if you or your child have diarrhea, to prevent the transmission of the disease.
  • Keep it Clean:  Be careful to not get lake water in your mouth. Wash your hands before eating and after changing a diaper. Shower afterwards if possible.

Summer Heat Attracts Swimmer's Itch

Swimmer’s Itch occasionally affects our City lakes and beaches. Here's what you should know about this annoying but harmless irritation:

  • To avoid becoming infected, towel dry immediately after exiting the water and shower afterwards, when possible.
  • Characterized by small, irritating red welts that appear after swimming. Sensitive individuals may itch for several weeks.
  • Occurs most often after swimming on hot, still summer days.
  • Caused by a parasite that infects birds and snails during different stages of its life. The parasite is unable to live in humans. 

LAURI

Lake Aesthetic and User Recreation Index (LAURI)

lauri graph for wirth lake

The Lake Aesthetic and User Recreation Index (LAURI) was designed to give recreational users a source of information about conditions affecting their use of city lakes.  The goal is to have an accurate, science based and easily understandable recreational indicator for the public.  The  LAURI has five indices:

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Public Health Index (E. coli measured at public swimming beaches)


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Water Quality Index (water clarity/Secchi depth)


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Habitat Quality (aquatic plant and fish diversity)


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Recreational Access (availability and ease of public access)


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Aesthetic Considerations (color and odor of water, garbage and debris)