Guide to Significant Wildlife Habitat - Door County Web Map

MINK RIVER / ROWLEY’S BAY SYSTEM
LOCATION:
This area, approximately 2900 acres, is located entirely within Liberty Grove Township at the
northern end of the Door Peninsula in Door County. As defined by the conservation planning of The
Nature Conservancy, this natural area covers parts or all of Sections 1, 2, 11, 12, 13, 14, 23, 24, 25, and
26 of T.32 N. – R. 28 E.; and part of Section 19 in T. 32 N. – R. 29 E. Several adjoining or nearby
significant natural areas are not included in this description, but the contiguous or adjacent position of
these sites should be considered when planning for the conservation of the broader landscape around the
Mink River. The Mink River Estuary, as a conservation site and State Natural Area, has been an ecoregional
priority for the Nature Conservancy since the 1970’s when they began buying land in the area.
The Conservancy now owns about 1500 acres and continues to acquire land in the area.
GENERAL SITE DESCRIPTION:
The Mink River / Rowley’s Bay system is situated in a north-west to south-east oriented bedrock
valley crossing the peninsula from Green Bay to Lake Michigan at the northern end of the Door Peninsula
and is considered a fresh water estuary. That is, the conductance and alkalinity gradient occurring in the
lower and mid-section of the river can shift either upstream or downstream in the river channel dependent
on the seiche activity in Rowley’s Bay and Lake Michigan.
Within this wetland system, the physical and chemical processes of the estuary impact the
function, species composition, and natural community structure of the affected wetlands. As a result of
seiche activity the water level in the estuary can fluctuate from 10 to 30 cm in approximately hourly
cycles, and considering longer periods, the dynamics of the Mink River hydrologic cycle changes from
year to year, affected by the changing levels of Lake Michigan.
Along with the periodic inflow of Lake Michigan water, other sources of water to the wetlands
bordering the river include precipitation, overland flow, and a series of groundwater springs found
primarily near the upland / marsh transition in the upper parts of the marsh at the head of the Mink River.
Overland flow from the watershed is thought to play a small, seasonal role as a water source to
the estuary. The precipitation levels and spring flow varies to a lesser degree throughout the year and
from year to year. The watershed boundaries are not well defined but encompass much of the Liberty
Grove Township landscape immediately north and south of the Village of Ellison Bay.
Alluvial fine sand, silt and clay and organic material underlie the marsh along the Mink River.
More specifically, the soils within the 600-foot contour consist primarily of Carbondale, Markey and
Rondeau mucks and soils of the Deford and Yahara series. These soils are typically saturated to depths of
a few feet, and while poorly suited for development provides for excellent wildlife habitat.
The upland soils bordering the core wetlands comprise Summerville, Longrie and Omena soil
series, and cover large areas in the western and northern portions of the watershed. These are generally
considered well-drained loams, and the erosion potential is considered moderate on level areas of this soil
but increases with increase in slope.
ECOLOGICAL SIGNIFICANCE:
The Mink River is an unaltered Great Lakes estuarine system and one of two large Lake
Michigan coastal marshes in Door County and it is one of the larger coastal wetlands on Lake Michigan.
The undisturbed nature of the wetlands and adjoining forests of this landscape and the large number of
rare species found here define the high ecological significance of the site.
The near pristine integrity in the plant communities and the lack of human disturbance in the
wetland complex has identified the Mink River Estuary as a natural area of statewide or greater
significance. Edging the shore of Rowley’s Bay north and east of the mouth of the Mink River the beach
and the series of sand ridges and swales support a number of rare or uncommon plants and natural
community types.
Mink River / Rowley’s Bay System 115