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