Monthly Lake Michigan Monitoring Program

In order to determine how human activities and exotic species introductions are affecting the water quality and general functioning of the Lake Michigan ecosystem, the Great Lakes WATER Institute operates a monitoring program in the Milwaukee region of Lake Michigan.

Monitoring sites extend from the Milwaukee Harbor to a pelagic station 16 km offshore, and include a perch spawning reef and an urban water intake area. The suite of measurements includes temperature, water clarity, water chemistry, phytoplankton and zooplankton abundance, and bacterial and plankton productivity. Some of these measurements are made directly from the research vessel Neeskay while others are made in the WATER Institute laboratories.


Clickable map of sampling sites

The red dots on the map above mark the sampling locations for WATER Institute monthly monitoring data. Click a red dot or the station name from the table below (recommended for non-graphic browsers) to view CTD or Chemistry data for any individual station.

Station Name (Abbr.) Description Approximate Depth (m) Longitude Latitude
Fox Point (FP) Lake Michigan 16 km east of Fox Point WI
Note: there is also searchable data from the Pelagic Buoy at this location.
100 -87.670833 43.1945
Green Can Shallow (GS) Lake Michigan east of St. Francis WI 10 -87.827283 42.981733
Green Can Deep (GD) Lake Michigan east of St. Francis WI 17 -87.8166 42.988683
Inner Harbor Junction (JC) Junction of the Milwaukee and Kinnickinnic Rivers 8 -87.904167 43.025
North Milwaukee Lake Michigan east of the UW-Milwaukee campus 18 unpublished unpublished
Outer Harbor North (ON) Inside the breakwater at the north boundary of the harbor 5 -87.886667 43.038333
Outer Harbor South (OS) Inside the breakwater at the south boundary of the harbor 7 -87.881383 43.015167

Background Information

These sites are visited on a monthly basis including winter. At each site, a variety of sampling techniques are used to provide physical, chemical and biological properties.

Monitoring site measurements include:

CTD Profiles:

A conductivity - temperature - depth (CTD) profiler is used to measure water quality parameters at small depth intervals from the surface to the bottom. Parameters measured include water temperature, conductivity, pH, dissolved oxygen, redox potential, scalar irradiance, turbidity (water clarity), and algal fluorescence.

Chemical Profiles:

Water samples are collected from specific depths using Niskin sampling bottles that are lowered and raised on a sampling cable connected to a winch. Water samples are returned to the laboratory and analyzed for dissolved and particulate nutrients (carbon, nitrogen, phosphorus, silica), algal pigments, protein, and the major ions chloride and sulfate.

Measurement details.

Database Structure

View field layouts and statistics for CTD and Laboratory measurements.


Russell Cuhel, PhD
UW-Milwaukee WATER Institute
Carmen Aguilar-Diaz, PhD
UW-Milwaukee WATER Institute

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