Crooked Lake Water Testing

City staff tests for E. coli levels at the water access at Crooked Lake through Labor Day. This is a new initiative that started July 29, 2019 after renovations at Crooked Lake Park were complete. Crooked Lake Park offers water access, with a small, sandy area that is available for the public to enjoy. No lifeguards are on duty and any swimming is at your own risk.

Current Results Week of July 29, 2019:
The test results are meeting the Minnesota standard for recreational waters (see table below for exact test results).


If E. coli levels exceed the standards set by the Minnesota Pollution Control Agency (MPCA), the water access will be closed temporarily until the readings return to a safe level. Information about the Minnesota state rule referencing E. coli levels for recreational waters is found below:

Minnesota Rule 7050.0222 Specific Water Quality Standards for Class 2 Waters of the State; Aquatic Life and Recreation: E. coli levels not to exceed 126 organisms per 100 milliliters as a geometric mean of not less than five samples representative of conditions within any calendar month, nor shall more than ten percent of all samples taken during any calendar month individually exceed 1,260 organisms per 100 milliliters. The standard applies only between April 1 and October 31.

Read more about water quality standards as recommended by the Minnesota Pollution Control Agency here.

What is E. coli?

E. coli is short for Escherichia coli, the scientific name for a group of bacteria found in the intestines and feces of warm-blooded animals such as mammals and birds. While most of the hundreds of strains of E. coli are harmless (one notable exception associated with food contamination is E. coli O157:H7), their presence can indicate sewage or feces-contaminated water which may include pathogens (disease-causing organisms).

Direct testing for pathogens is expensive and impractical, as pathogens are rarely found because they usually occur sporadically and at low levels. Instead of testing for the pathogens themselves, public agencies test for the presence of "indicator" species, so called because their presence indicates that sewage or fecal contamination may have occurred. The two most commonly used indicators for recreational waters are fecal coliforms and E. coli.

Interpreting the Results

Two samples are collected weekly from Crooked Lake with results listed in the table below. If E. coli levels exceed those recommended by the state, the water access area will be closed temporarily until further testing shows safe levels.

Conditions which impact E. coli levels include rainfall (materials harboring the microorganisms can be washed into the water from the surrounding landscape), concentrated waterfowl numbers (one reason why feeding waterfowl is prohibited), and high temperatures. For more information call 763-767-6576.

Table 1. E. coli Test Results for Crooked Lake (taken at water access area off 13180 Crooked Lake Blvd.) 

Results are given in MPN/100 ml (approximate number of viable cells per 100 milliliters, MPN stands for Most Probable Number), and geometric means will become available after more testing is complete as time goes on. As the City continues to monitor bacteria levels, determinations will be made as to when single testing levels exceed the standards to close the water access area.

Crooked Lake Bacteria Test Results

Test Date Test Results Test Location
July 29, 2019 First time testing 10 MPN/100 mL Crooked Lake Beach North
  17 MPN/100 mL Crooked Lake Beach South
August 5, 2019 23 MPN/100 mL Crooked Lake Beach North
  18 MPN/100 mL Crooked Lake Beach South
August 12, 2019 88 MPN/100 mL Crooked Lake Beach North
  62 MPN/100 mL Crooked Lake Beach South
August 19, 2019 435 MPN/100 mL Crooked Lake Beach North
  4 MPN/100 mL Crooked Lake Beach South