Back in April, we asked you to speak up for the trout streams at risk with the proposed development of a data center in Hermantown. 

The City of Hermantown has since reviewed public comments and on Aug. 4 submitted its updated Alternative Urban Areawide Review (AUAR) to the Minnesota Environmental Quality Board. Hermantown City Council is anticipated to review the final AUAR for adoption this fall. 

We urged the city to consider a different location for this development because the proposed site sits in the most sensitive part of the Midway River Watershed, between two of the watershed’s coldest and most productive trout fisheries. 

The proposed development would convert wetlands, forests and grasslands to impervious surfaces, potentially impacting the groundwater recharge that feeds these streams through spring flow and increasing stream temperatures to above what brook trout require to thrive. 

Under the proposed scenario, impervious surfaces would increase from 11 to 126 acres in the study area with 32 acres of wetlands lost and 95 acres of woodland lost. 

Recently, we followed up with the City of Hermantown about the possibility of considering a different location in the watershed for the proposed development. In response, the city said the developer, Google, chose the selected location due to its proximity to existing power infrastructure and the availability of municipal water and sewer extensions among other advantages for development. 

Those factors may make the site desirable from a development perspective, but they don’t answer whether a project of this size can avoid compromising vulnerable coldwater resources.

In a recent city council work session discussing the updated AUAR, an environmental consultant for the project acknowledged that the proximity of trout streams, wetlands and shallow groundwater will require evaluation of water temperatures. 

The updated review outlines additional field work with state agencies to identify springs, seeps and other groundwater discharge features to better understand connections between the groundwater, streams and wetlands. Those evaluations are underway to inform final design plans. 

In the meantime, it’s still unclear how much groundwater discharge to trout streams could change and how water temperatures could change as a result. With an expected city council deliberation this fall, we’ll watch to learn the findings from the groundwater evaluation and how these concerns will continue to be addressed. 

In our April comments, we also called for the examination of all possible approaches to stormwater management, especially plans that retain or enhance existing filtration to groundwater to ensure water leaving the site will not be warmer than it is under current conditions. 

The updated AUAR outlines the same stormwater management plans with more explicit language around coldwater protection. The plan, informed by the Minnesota Pollution Control Agency’s requirements for discharge into trout streams, must minimize any increase in temperatures to trout streams. 

The current stormwater management plan controls runoff rate, sediment, pollutants and temperature and utilizes a filtration system that collects runoff from impervious surfaces, treats it in eight filtration basins and routes the treated water through existing wetlands before reaching coldwater streams. 

The question remains, will that be enough to offset the loss of cold groundwater infiltration caused by the increase in impervious surface. 

State agencies reviewing the AUAR have until Aug. 14 to file any objections. If there are no objections, the City of Hermantown can move forward on adopting the final AUAR.