Mahon Creek Water Monitoring Station

Mahon Creek
Mahon Creek originates south of Highway 57 and flows through old fields and a housing development onto the UW-Green Bay campus where the stream flows through Mahon Woods and into the bay of Green Bay. The map below shows the boundary of the Mahon Creek watershed and the position of the water monitoring station. Due to rapidly shifting variables, a continuous automatic monitoring system was needed to accurately characterize hydrology and water quality in the stream. A permanent station was installed in December of 2010 with the help of staff, students, and several generous donors. The data provide an important educational resource for students and is used to help manage water quality on the UW--Green Bay campus, Mahon Creek watershed and the bay of Green Bay. The station is maintained by NAS faculty member Dr. Kevin Fermanich, Watershed Analysist Paul Baumgart, and students in Dr. Fermanich's laboratory.

Stream height (stage) is monitored continuously in Mahon Creek and in a stormwater culvert located 75 feet away from the stream. Stream discharge (volume/time) is periodically measured manually with an OTT acoustic digital current (ADC) meter, and stage is recorded at the same time as the flow measurement. Other sensors record water temperature, pH, dissolved oxygen and conductivity continuously during ice-free periods.  A Campbell Scientific turbidity probe was installed in July 2012, and it is recording turbidity at 5 minute intervals during storm events, and less frequently at other times.  This will allow UW—Green Bay researchers to establish a relationship between turbidity and SSC, particulate P and total P so that we can estimate concentrations and constituent loads on a continuous basis.

During run-off events such as during and after storms or during major snow melt, samples are automatically collected based on the rise and fall in stream height. Samples are also collected manually during low flow conditions. Samples are analyzed in the UW—Green Bay chemistry laboratory for Total Phosphorus, Dissolved Phosphorus and SSC (suspended solids concentration).  A sufficient number of samples are being collected that researchers are able to calculate daily loads when the data are coupled with our continuous flow record. 

The permanent station was constructed in winter 2010/2011. The shingled building that houses the sampling and electrical equipment was designed to blend in with the surrounding forest.


  • Continuous stream height (stage) in Mahon Creek is recorded with an OTT bubble sensor pressure transducer. 
  • Stream stage in the culvert is recorded with a Druck pressure transducer.
  • Stream discharge (volume/time) is periodically measured manually with an OTT acoustic digital current (ADC) meter.
  • A Hydrolab Multiparameter sonde is located within each stream and data are transmitted through a direct cable connection to the Mahon Station. Water temperature, pH, dissolved oxygen and conductivity are recorded continuously.
  • Campbell Scientific turbidity probe (in culvert)
  • Stream stage is recorded with a Druck pressure transducer. 
  • Runoff event samples (TP, DP and SSC) are collected from Mahon Creek throughout an event with a refrigerated ISCO automated sampler. TP and DP are analyzed with the Lachat block digestion and Flow Injection Analysis system. * Campbell Scientific turbidity probe (in culvert).
  • Continuous stream discharge and daily loads of TP and SSC will be derived.

We would like to thank the following generous donors for contributing funds, equipment, materials, and labor toward the construction and operation of the Mahon Creek Station:

  • Cofrin Center for Biodiversity
  • 1923 Fund (primary donor)
  • Van's Lumber & Custom Builders (materials and labor)
  • Wisconsin Public Service Corporation (sondes)
  • Prefinished Staining Products, Inc. (siding)
  • UW – Green Bay Facilities Department
  • USGS - Wisconsin Water Science Center (equipment and expertise)