3.5 Groundwater

  1. Development of the subwatershed has resulted in increased stormwater volumes and flow peaks and reduced infiltration and base flow in Minnehaha Creek.  Development, redevelopment, and reconstruction in the subwatershed may provide opportunities to decrease stormwater runoff volumes and increase infiltration.
  2. Ongoing flow monitoring in Minnehaha Creek suggests that some reaches of the creek are losing flow to groundwater, possibly contributing to periods of low or intermittent flow.
  3. Seeps and springs are present in the subwatershed, mainly in the limestone cliffs of the Gorge.  The most prominent spring is Camp Coldwater Spring.  Hydrologic analysis and monitoring conducted at the time the Minnesota Department of Transportation proposed to construct a new highway interchange nearby indicate this historic spring is sensitive to impacts in its groundwatershed.
  4. The extensive wetlands in the upper subwatershed were identified in the FAW as either discharge wetlands or combination recharge-discharge wetlands.  It will be critical to maintain or increase infiltration rates in the upper subwatershed to help maintain hydrology to these wetlands.  Wetlands in the lower subwatershed are mainly recharge or combination wetlands.  The hydrology of these wetlands depends on maintaining local flow patterns and rates.
  5. Much of the subwatershed is very highly or highly sensitive to aquifer impacts, including the Minnehaha Creek corridor.
  6. Wellhead Protection Areas have been identified for the cities of Edina, Minnetonka and St. Louis Park within this subwatershed.  Stormwater management within those areas should be coordinated with wellhead protection plans.