Find answers to some of our frequently asked questions about water in the park system.


Where are swimming beaches located on Minneapolis lakes?

See beach locations to find out about directions, lifeguard status, facilities and more.

After a rain event should I wait to swim in Minneapolis lakes?

Yes, that’s a good idea. Rain washes waste off streets from waterfowl and pets into storm sewers and lakes. High bacteria levels generally occur immediately after a rain event and return to normal levels within 48 hours. The day following a rain event is not a good time to bring small children to a beach. See the beaches section for more information.

What is swimmer's itch and how can it be avoided?

swimming on hot summer days. It is caused by a small parasite that, other than causing this rash, is harmless to humans. To avoid swimmer’s itch, towel-dry upon exiting the lake and shower if possible. See the beaches section for more information.

Which lake is the best for swimming?

There are many different opinions about what conditions make for the best swimming experience. 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.

To ensure a healthy and enjoyable experience for swimmers, the water at the public beaches is monitored by the MPRB for E. coli, a bacteria that can be an indication of health risk for swimmers. Check the Current Beach Status for up to date information throughout the summer season.

Water Monitoring

How often are lakes monitored?

The MPRB monitors the water quality of Brownie, Calhoun, Cedar, Diamond, Grass, Harriet, Hiawatha, Isles, Loring, Nokomis, Powderhorn, Spring, and Wirth Lakes. Lakes are monitored from April through October and periodically during the winter months.

What is the water monitored for?

Park Board Water Quality Specialists use special equipment in the field to monitor temperature, pH, conductivity, dissolved oxygen and water clarity. Phytoplankton and zooplankton, microscopic plants and animals that are vital to the lake community, are sampled throughout the year. Samples are collected and brought to an independent lab for testing. Sample analysis includes a large profile of parameters, including alkalinity, nitrogen, chloride, chlorophyll-a, and phosphorus.

What does water quality monitoring tell us?

Chlorophyll-a, phosphorous and water clarity levels are used to determine a lake’s fertility, or trophic state. When these measurements are applied to a mathematical formula, called a Trophic State formula, a Trophic State Index (TSI) score from 0 to 100 is produced. Higher numbers in the TSI scores indicate that a lake is fertile. A fertile lake is a lake that has many aquatic plants, fish and algae present. Fertile lakes with high TSI scores often have water that looks like “pea soup”. Less fertile lakes, with lower TSI scores, look more like swimming pools with clear water.

Changes in lake water quality can be tracked by looking for trends in TSI scores over time. These scores are especially important for monitoring long-term trends (5-10 years). Historical trends in TSI scores are used by lake managers to assess improvement or degradation in water quality.

Is the stormwater entering our lakes and rivers monitored?

Minneapolis Park and Recreation Board water quality staff have monitored the stormwaterthat enters lakes since the late 1990s. At selected sites in the city, automated stormwater samplers are placed in storm sewers. When rainfall occurs, the samplers automatically draw water from the storm sewer, which is then collected and taken to a laboratory for testing. The Minnesota Pollution Control Agency issued a National Pollution Discharge Elimination System (NPDES) permit to assist in monitoring and educational activities that will improve the quality of stormwater entering lakes, rivers and creeks.

What is done with the information gathered?

Data collected over the years shows trends in water quality and how nutrients impact lakes. From this data we can determine suitable management methods and tools for improving water quality in our lakes. Data is submitted to the Minnesota Pollution Control Agency and various organizations that have a stake in the health of the lakes in Minneapolis

As a result of the data collected, efforts have been implemented to improve the water quality of city lakes. Stormwater retention ponds, grit chambers, and rain gardens have been installed throughout the park system. The purpose of these structures is to allow nutrients such as phosphorus and sediments to settle out of the stormwater before it enters lakes. Alum treatments have been applied to some of the lakes to reduce phosphorus in the water. Aeration systems have been installed in lakes that have experienced low oxygen levels to provide better habitat for fish and reduce fish kills.

The ultimate goal of water quality monitoring is to improve the water quality of our lakes and rivers to ensure that future generations can have clean and healthy water to use and enjoy.

Is the drinking water from hand pump wells tested?

Yes, drinking water from hand pump wells is tested for nitrates and E Coli. See the wells section for more information.

Why is the Park Board concerned about Aquatic Invasive Species?

Aquatic Invasive Species threaten native plants and animals, which in turn change the lake’s ecology. These changes can significantly interfere with both the beauty and recreational use of the lakes.

Water Recreation

Can I use gas outboard or electric boat motors on Minneapolis lakes?

Gas motors are not allowed on Minneapolis lakes except by police, MPRB staff and those permitted as safety boats for events; however, electric trolling motors are allowed. Visit the boat launch section for more information about boating on Minneapolis lakes.

Is fishing allowed on Minneapolis lakes?

Fishing is allowed on Minneapolis lakes. Visit the Minnesota DNR website for fishing regulations.

What kind of ice house may I have on Minneapolis lakes?

Ice houses are only allowed on Minneapolis lakes from 6 am-midnight. Portable ice houses are usually the easiest to set up and remove daily.

Can I eat the fish I catch in Minneapolis lakes?

The Minnesota DNR has information about contaminants found in fish in specific lakes available through LakeFinder.

Where can I enter or exit Minnehaha Creek to canoe?

There are approximately 18 sites to enter and exit Minnehaha Creek between Gray’s Bay Dam and Longfellow Lagoon. The Minnehaha Creek Watershed District has canoe route maps available online.

Community Impact

What can citizens do to improve water quality?

  • Sweep up any fertilizer that lands on hard surfaces and put it on the grass.
  • Sweep up grass clippings, leaves, litter and debris from the curb.
  • Use less sand and salt on your sidewalk and driveway.
  • Compost or mulch your leaves.
  • Pick up after your pet.
  • Dispose of motor oil or other automotive fluids properly. These materials can be taken to a Hennepin County drop off site, which is free of charge to residents.

Why is it harmful to feed waterfowl?

Geese and ducks naturally feed on aquatic plants, grasses and small crustaceans. It is believed that the processed foods people feed them do not provide the range of nutrients the birds need for a healthy diet.

Feeding geese may make them more aggressive toward people. Geese who are accustomed to being handfed expect food from people and may aggressively approach people who do not have food.

Why are high populations of waterfowl detrimental?

Large populations of waterfowl in a small area cause soil compaction, shoreline erosion and damage to vegetation. This damage to soil and vegetation has negative impacts on the recreational and environmental quality of the area around the lake.

Concentrations of waterfowl result in a large quantity of bird droppings. Droppings contain phosphorus, which can contribute to algae growth in water. Excessive algae growth is harmful to the ecosystem and aesthetics of a lake. As algae die and decay algae use up oxygen. Low oxygen levels in a lake lead to fish kills and foul odors. Large quantities of algae in a lake are called algae “blooms” or “scums”, when there are high levels of algae, the lake becomes green, smelly and unpleasant to swim in.

Additionally, waterfowl droppings may contain bacteria and viruses. Waterfowl are hosts of the familiar parasite that causes swimmer’s itch. Feeding waterfowl, particularly around beaches and docks, may contribute to swimmer’s itch; reducing the recreational quality of these public areas.

If you are picnicking in an area where waterfowl congregate be sure to wash your hands thoroughly and make sure pets and children do not ingest waterfowl droppings.

Many cities are now banning feeding waterfowl in parks. So for the benefit of people, birds and the environment please don’t feed the waterfowl.