2.3.2 Biologic Integrity

Landscape

Four areas within the subwatershed have been identified by the DNR as regionally significant ecological areas (see Figure 6).  This includes the area around and to the west of Lake St. Joe; the eastern shores of Lake Minnewashta, including Lake Minnewashta Regional Park and Camp Fire’s Camp Tanadoona; and two areas within the Landscape Arboretum. 

Lakes

Table 1 below details fish survey data available within the subwatershed.   Lake Virginia has as recently as 2001 been stocked with walleye fry (newly hatched fish).  A fish species of state special concern, the least darter, has been observed in Lake Minnewashta.

Table 1.  DNR fish survey data.

Lake 

Survey Year

Fishery

Dominant Fish

Minnewashta

2001

Sport

Northern pike, largemouth bass, bluegill, yellow bullhead

Virginia

2003

Sport

Northern pike, walleye, largemouth bass, bluegill, black crappie, yellow perch

St. Joe

1994

Pan

Black bullhead, sunfish spp., northern pike

Tamarack

1994

Pan

Black crappie, bluegill, yellow bullhead, northern pike

Source: Minnesota DNR.

The Minnesota Department of Health, Minnesota Pollution Control Agency (MPCA), and the DNR have collaborated to monitor fish for contaminants at over 1,000 sites in Minnesota.  Fish from popular lakes and streams and those from known or suspected polluted sites are routinely collected and tested for mercury, which is found in most fish tested in Minnesota lakes, and PCB contamination.  These test results are used to monitor pollution and to provide more specific fish consumption advisories beyond the general advisories for Minnesota.  More detailed fish consumption advice that is similar to or slightly more restrictive than the general advice has been prepared for both Lake Minnewashta and Lake Virginia.  Mercury contamination is being addressed by a region-wide TMDL process by the MPCA.

Eurasian watermilfoil has been confirmed in Lake Minnewashta since 1989 and in Lake Virginia since 1988.   A vegetation survey performed for the City of Chanhassen on Lake Minnewashta in 2001 found the vegetation community dominated by coontail and Eurasian watermilfoil throughout the lake, with some curlyleaf pondweed present in a few locations.  Lake users note that the milfoil forms thick mats in portions of the lake.  A vegetation survey performed for the City of Victoria on Lake Virginia found curly leaf pondweed in about 50 percent of the littoral area, although at a low abundance.

A vegetation survey performed for the City of Chanhassen on Lake St. Joe in 2001 found no Eurasian watermilfoil in that lake; no information is available for Tamarack Lake.  The only submergent plant found in Lake St. Joe was coontail.

Wetlands

The 2003 MCWD Functional Assessment of Wetlands (FAW) identified several wetlands with exceptional vegetative diversity in the area around Lake St. Joe and in Lake Minnewashta Regional Park (see Figure 13).   Wetlands north of Lake Virginia were classified as high vegetative diversity.  Several wetlands abutting the lakes in the subwatershed were classified as containing high value wildlife habitat or exceptional to high value fish habitat.