Water Quality Monitoring
We all know that nutrients such as Nitrogen and Phosphorus are required by living things, but too much isn’t good. These nutrients are commonly measured in lakes because the amount of nutrients can influence the type and abundance of phytoplankton (Diatoms, green algae, blue-green algae) in water. Lakes with high water quality contain low amounts of phosphorus and are considered oligotrophic, dominated by diatoms. Lakes with poor water quality contain high amounts of phosphorus. They are considered eutrophic and are dominated by blue-green algae.
The lakes and streams of Leelanau County are all oligotrophic, which means they are relatively clean and clear. This water enriches the lives of both the permanent and seasonal residents of the area. These water resources are significant recreation and tourist attractions, crucial to the health and vitality of the local economy. Back in the 1990s, Dr. Tim Keilty started our water quality program when he realized that credible strategies that have a valid and strong scientific foundation were needed to protect these important resources. This program was designed to provide baseline and long-term water quality data.
More than 35 years later, the program and database are maintained and supported by the Leelanau Conservancy. Our data, hosted on the Leelanau Clean Water database, provides an overview of water quality trends over time, from 1990 to present day.
This chart shows the Trophic Status Index which demonstrates that the lower the Total Phosphorus (TP) and Chlorophyll-a, the clearer the water (or Secchi Disk readings).
What Data Do We Collect?
We currently sample and analyze water quality variables in seven major lakes and 19 streams throughout Leelanau County, from May to October. Sampling takes place in the same locations, using the same laboratory and methods.
Lake data parameters include Total Phosphorus, Nitrates/Nitrites and Chlorophyll. We also gather other data at each location using a Hydrolab, which collects Temperature, Dissolved Oxygen, pH, Conductivity, and Oxidation Reduction Potential, throughout the water column. We collect Secchi Disk readings at each lake to track water clarify.
Our stream sampling is conducted by dedicated volunteer teams, who collect samples and parameters including Discharge (Flow), Total Phosphorous, and Water and Air Temperature.
Lake and Stream Data
Our data is publicly available and hosted on the Leelanau Clean Water database, which can be found here: www.leelanauwaterquality.org.
