Water Level Monitoring Provides Concrete Data for Long-term Wetland Study

Kjolhaug Environmental Services, a natural resource consulting company based in Shorewood, Minnesota, provides a comprehensive range of solutions including wetland delineations, hydrology studies, permitting, and other environmental-related services.

In early 2016, Kjolhaug began an annual monitoring program examining the vegetation and hydrology of a series of wetlands located in the Twin Cities metro area. Driven by requirements under the Minnesota Wetland Conservation Act, the purpose of the study is to document any changes to six existing wetlands from construction of a 104-acre single-family residential development containing 130 homes, which is being built around the wetlands.

As part of this effort, Kjolhaug is monitoring water table levels to assess any hydrology-related impacts to the wetlands, including long-term hydrologic losses or gains.

“We are collecting data to verify that the wetland hydrology will be preserved and that it is not reduced by development activities or any changes to the drainage areas leading to the wetlands,” said Adam Cameron, wetland ecologist with Kjolhaug Environmental Services.

Monitoring is being conducted concurrent to construction and will continue after the project is completed. “In particular, we will be focusing on any changes that may occur in the next few years as a result of mass grading and the addition of impervious surfaces,” Cameron said.

To track water levels, Kjolhaug is utilizing HOBO® MX2001 Bluetooth water level data loggers from Massachusetts-based Onset. The instruments provide wireless access to water level and temperature measurements right from a mobile phone or tablet. This, in turn, means that users don’t need to take a laptop computer out to the field or pull loggers out of a well to download data. And, no internet access is necessary: the data logger and mobile device are all that’s required.

Kjolhaug’s team deployed a total of six loggers at the fringes of the wetlands. The loggers are housed in PVC tubes that are surrounded with sand and capped with bentonite.

“We installed the loggers at perimeter points where standing water is not present, forty-eight inches below the soil surface,” Cameron noted. “This way, we can measure how low the water table drops and how close it comes to the surface throughout the season.”

Cameron and his colleagues visit the project site every two weeks to retrieve data, which are downloaded on iPhones using Onset’s accompanying HOBOmobile® app. The free app allows the team to enter reference water levels, view level data, check logger status (a particular advantage during installation), share data files for analysis in spreadsheets, and store data in the cloud.

“The Bluetooth data loggers and mobile app are a huge convenience since we can access data from 100 feet away, saving us a lot of time and avoiding the need to physically traverse any fences,” Cameron said. “Additionally, we don’t have to pull the loggers out of the tubes and plug them into a device to upload data, which could possibly alter the positional depth, leading to inconsistent data. So, in this regard, the Bluetooth feature is key to ensuring that the data is sound.”

According to Cameron, the Bluetooth capability also offers the convenience of streamlined installation and setup, allowing the researchers to quickly calibrate the loggers and confirm functionality.

Following a full year of monitoring, Kjolhaug will analyze trend data, prepare its first annual report, and present findings. The annual reports will evaluate any hydrology-related impacts to the wetlands during and after development, utilizing pre-development conditions as a reference point.

“One of the most important aspects of these data loggers is that they enable for extremely accurate data,” Cameron said. “Compared to other data collection methods, which may not be as reliable, the HOBO loggers provide concrete evidence, eliminating the need for a best professional judgment. This type of data is invaluable for helping overcome any uncertainty that may arise in the minds of regulators.”