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Central Sands Lakes Study Data Collection and Monitoring

As part of the Central Sands Lakes Study (CSLS), the DNR partnered with the Wisconsin Geological and Natural History Survey (WGNHS), the United States Geological Survey (USGS) and the UW-Stevens Point Center of Watershed Science (UWSP) to conduct fieldwork and monitoring throughout the Central Sands. The study included an extensive data collection effort including: monitoring lake and groundwater levels, various fieldwork, surveys and hydrogeologic methods. These data aid in the creation of a groundwater flow model to evaluate impacts of changing water levels on the three study lakes. View a snapshot of data collected as part of this study. Our technical appendices and series of presentations include more details on the study data collection and methods.

CSLS By The Numbers info graphic


Below are some types of monitoring equipment that have been used for the study, the type of data collected and how data are used. If you have questions about the field instrumentation, please contact Adam Freihoefer.


Water level data

These monitoring methods collect water quantity data that are used for constructing and calibrating a groundwater flow model. Water level data can be viewed on the Wisconsin Water Quantity Data Viewer.

Gaging stations

USGS has installed and maintained gage stations on lakes and streams to continuously monitor water levels and stream flow. The metal boxes contain monitoring equipment, and a pipe extends from the box to the water body to measure flow/water levels. The gages are powered by nearby electricity or solar panels.

Plainfield USGS Lake Level Gage © DNR
Plainfield USGS Lake Level Gage © DNR.


Instantaneous flow measurements

The DNR, UWSP, County Staff and volunteers in the Central Sands collect flow measurements on rivers and streams throughout the Central Sands. 

UWSP staff measuring flow © UWSP Watershed  Science Center
UWSP staff measuring flow © UWSP Watershed Science Center.


Monitoring wells & pressure transducers

Long-term groundwater monitoring wells are located throughout the Central Sands. Water levels are measured manually on weekly, monthly or quarterly basis or continuously with a pressure transducer. USGS staff maintain well sites and check data regularly for quality assurance. 

Monitoring well and pressure transducer © USGS
Monitoring well and pressure transducer © USGS.

RTK GPS units

DNR staff collect lake and stream elevation data using a survey-grade GPS at a high level of precision and accuracy.   

DNR staff using a RTK GPS unit © DNR
DNR staff using a RTK GPS unit © DNR.


DNR and WGNHS staff use piezometers near the Central Sands study lakes to gather groundwater gradient data. These on-shore devices collect data at different depths below the ground surface. They are outfitted with transducers for continuous monitoring during the study. Piezometers are used to estimate the amount and direction of groundwater inflow to the lakes.    

Nested piezometers © WGNHS
Nested piezometers © WGNHS.

Lake gages

Local volunteers and county staff read and record lake stage at staff gages on some lakes in the Central Sands.

Lake staff gage © DNR
Lake staff gage © DNR.
Geologic data

The Wisconsin Geological and Natural History Survey and USGS conducted most of the fieldwork and data collection to characterize the geology and hydrology in the study area and better understand the groundwater connection to Plainfield, Long and Pleasant Lakes. Read the WGNHS Letter for more information.

Lake profiling

The WGNHS used a canoe outfitted with monitoring equipment to obtain lake water chemistry and lakebed characteristic data. This profiling helped identify areas where groundwater was seeping into the lakebed.   

Canoe conducting lake profiling © WGNHS
Canoe conducting lake profiling © WGNHS.

Seepage meters

WGNHS and DNR staff installed seepage meters on each lake to  directly measure the flow of water between groundwater and the lake. 

Seepage meter © DNR
Seepage meter © DNR.

Subsurface geophysical methods

WGNHS used subsurface geophysical methods to provide quick estimates of depth to bedrock or other subsurface features that may influence groundwater flow. These methods do not disturb the earth and are low-cost options. WGNHS used the following geophysical methods in this study: passive seismic, active seismic, ground penetrating radar and electrical resistivity imaging.  

Staff from WGNHS using a passive seismic instrument © WGNHS
Staff from WGNHS using a passive seismic instrument © WGNHS.

Exploratory drilling

WGNHS used exploratory drilling in areas surrounding the three lakes provide information to characterize the geology and hydrogeology. Geoprobe drilling (shown here) efficiently obtains subsurface samples to determine detailed geologic profiles. Rotosonic drilling uses high-frequency vibrations to quickly drill to greater depths, through sediments, boulders and bedrock. WGNHS described and documented all drilling samples to aid in writing their Hydrostratigraphy report.    

Exploratory Drilling
Geoprobe drilling rig © WGNHS

Lakebed piezometers

Staff placed lakebed piezometers to measure and evaluate vertical gradient. These temporary lakebed piezometers, used with the seepage meter data, aided in estimating how groundwater flows through the lake bed.  

Installation of lakebed piezometer © DNR
Installation of lakebed piezometer © DNR.
Lake Characteristics & Resource Evaluation 

As part of the Central Sands Lakes Study, DNR staff monitored the study lakes for the parameters listed below to help characterize lake conditions. DNR determined how changing water levels would impacts the three lakes’ ecosystems including: human use, fish, plants and water chemistry.

Ecological surveys

DNR staff surveyed habitat, fish populations, and plant communities to understand the ecology of the lakes. 

Seining for fish along the shores of Pleasant Lake, WI © DNR
Seining for fish along the shores of Pleasant Lake, WI © DNR.

Groundwater-surface water interactions

DNR staff collected water chemistry samples from the three study lakes and  nearby monitoring wells to understand groundwater-surface water interactions. 

Collecting water samples
Setting up to collect water chemistry samples from monitoring wells © DNR.

Water level surveys

The DNR conducted surveys for features such as beaches and piers, as well as a social survey to determine how human use is affected by potential changing water levels in the study lakes. 

Dock on Long Lake © DNR
Dock on Long Lake © DNR.


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