Comprehensive Conservation Plan | Detroit River W. Lk Erie Indicator Project | Fact Sheet | Articles | What's New | News Releases
Humbug Marsh | Grassy Island | Reports | Partners | Contacts | Refuge Map | Home
Environmental Setting
Environmental Setting Links to other reports on Humbug Humbug Home Source: Environmental Assessment, United States Army Corps of Engineers
Description of Area:
The Detroit River carries the outflow of Lake St. Clair to Lake Erie of the Great Lakes Basin. It forms the border between Wayne County in southeastern lower Michigan and the Canadian Province of Ontario. Area land use is high-density residential/heavy industry/municipal. Natural resources include the river itself, which provides residential and industrial water supplies, transportation of bulk materials and commodities along the St. Lawrence Seaway, and recreational opportunities. Development is concentrated along the river area. Recreational boating is popular within the last two decades. This area south of the City of Detroit is known as “Downriver” and has been heavily hit by this economic dislocation.
Waterway Characteristics:
The Detroit River has a large discharge averaging 144,400 cubic feet per second and a rapid flow with an average velocity of 1.4 feet per second. Shorelines along most of the Detroit River are developed and armored by riprap or bulkheads, particularly on the mainland shore. Both private and public boat docking facilities are common, but not as prevalent as industrial, utility, and factory uses. Water quality in the Detroit River overall is considered fair, it generally meets established water quality standards due to recent controls established on discharges. This particular area, known as the Trenton Channel, receives outflows of the River Rouge, which is heavily polluted. The sediments in the river have high concentrations of contaminants typical of industrial wastes of many decades, such as heavy metals and organic compounds. Slower and backwater areas of the river which are recognized for sediment accretion, including the shallows on this site and the drains on the property, are likely to have particularly high concentrations of contaminants.
The Detroit River is identified as an Area of Concern (AOC). AOCs are degraded habitats identified by the International Joint Commission (IJC). Many areas within an AOC contain an elevated level of contaminants.
The 32-mile Detroit River shoreline is highly developed. From the Lake St. Clair outlet to the northern project boundary, the entire mainland side of the Detroit River is bulkheaded or armored and developed with homes, businesses, factories, or abandoned buildings. Except for a small wetland at Elizabeth Park, Wayne County, all wetlands on the mainland side of the Detroit River upstream of the site have been filled or bulkheaded. Some wetland complexes remain on the islands located on the Detroit River, the Canadian side of the Detroit River, and downstream of the site on the shoreline of Lake Erie.
Description of Humbug Complex:
Humbug Island is primarily upland with some wetland fringes, particularly at the north and south ends of the island. The northern third of the island consists of mature hardwoods. Second growth areas extend southerly, with dense shrubs along the western shore. There are sand banks along the east side, some of which are eroding. The overall habitat conditions are very diverse due to varied topography, and differences in age and physiognomy of vegetation. Also, since it is an island, it is separated from disturbances near the mainland and surrounded by very shallow waters. Discharges of warm water from industries upstream maintain a sizeable area along the east side of the island in an ice-free condition most winters. The island provides potential and observed habitat for migrating songbirds, resting and feeding area for raptors, herons, and shorebirds. The island provides a visual screen between the shallow marsh area and human activity of boating and recreational water use on the open river to the east.
During a site visit in October 1998, a biologist from the Detroit District and a representative of the Great Lakes and Ohio River Division observed a concentration of at least 5 ospreys either roosting on or flying directly over Humbug Island. Osprey are rarely seen in the metropolitan Detroit areas. During the same visit, they saw numerous egrets roosting in trees on the Island. A bald eagle was observed on Humbug Island during a site visit on August 19, 1999 by Gary Mannesto, Wally Gauthier, Melissa McPherson, and Dave Gesl, of the District's Regulatory Branch. Other sightings of these raptors are reported in the public and agency comments which we received. There have been reports of bald eagles and osprey eating their catches in the trees of the island.
In the past, we received much anecdotal information from local residents and others (Encl 38a-g) that there has been a unique congregation of great blue herons that overwinter in the area. According to reports, the flock spends the day on Calf Island and then flies across the channel to the project island, and perhaps to the project mainland. The reasons that observers give us for this use of these sites is that they are undeveloped islands where they are not disturbed by human or other intrusions, that the river stays open in this reach, probably due to thermal discharges upstream, and that there is an adequate food supply available. These conditions are unique not only to the immediate area, but possibly to Southeast Michigan as a whole. At other times of the year, numbers of herons are down, but other seasonal residents and migrants such as great egrets, greater yellowlegs, doublecrested cormorants, grebes, bitterns, and gallinules use the shorelines of the area because of its combination of favorable, undisturbed conditions.
Humbug Marsh includes all of the shallow waters located between the island and the mainland, the shallows east of the island to a point where there is a distinct drop off into the river channel, and the shallow waters which extend up drains on the property. In short, it includes all areas that are subject to inundation by the Detroit River, and to "seiche" events in which Lake Erie fluctuates due to sustained high winds blowing across its long axis. It includes wetlands that are also more or less contiguous and banding upslope due to saturation, as opposed to runoff.
The east side of Humbug Island is bordered by a shallow water shelf extending up to 1,300 feet in length to the east, dropping off into deeper water. Because of the man-influenced alterations of the majority of the Detroit River shoreline, the vast majority of similar shallow water shelf has been eliminated through filling and bulkheading. Review of the navigation charts shows deeper waters along much of the mainland riverine shoreline. This shelf supports several acres of communities of submerged aquatic macrophytes such as water celery, as well as invertebrate communities that afford feeding habitat for migrating and resident waterfowl, and fish spawning, nursery, and feeding habitat. Vegetated shoals are relatively scarce in this riverine system. Fishermen routinely drift fish with the current downstream from the power plant's warmwater effluent, along the deep waters east of the Chrysler site, fishing the edge of the drop off. Scientific and local knowledge and belief suggests an abundance of walleye migrate in the Detroit River, with large seasonal congregations taking place adjacent to, and possibly to a lesser degree within the project site. In the spring, large numbers of anglers are known to fish the waters east of the island during what is colloquially referred to as "the spring walleye run". This is one of the larger, if not the largest seasonal congregation of fishermen in the river. Elizabeth Park, located upstream, has one of the most heavily used boat launch sites in the state, primarily used by fishermen in the spring.
The shelf is also used before and after the fishermen by large rafts of canvasbacks, scaup, and many other species during seasonal migrations. These birds are very wary of human disturbance. During the summer, there are large congregations of other resident duck species.
The portion of Humbug Marsh located between the mainland and the island varies in water depth and habitat compositions and is governed in part by water levels in Lake St. Clair, the Detroit River, and Lake Erie and can be influenced by wind direction. It provides habitat for a variety of invertebrates and vertebrates including, fish, reptiles, amphibians, mammals, and birds. Ducks nest and feed in and adjacent to the wetlands. Muskrats and raccoons forage in the wetlands. Raptors, including osprey and eagles feed on fish in the shallow waters of the wetland complex. The site is protected from waves by Humbug Island. The open water, wetland complex on-site is used as a nursery area for a variety of game fish species including Centrarchidae, Esocidae, Percidae, and forage fish from Cyprindidae. Extensive fish sampling data is available for this site and immediately surrounding areas (Encl 39; see also Encl 34).
Continental migrations of songbirds such as warblers are known to occur up the river in the spring and fall. Stopover habitat for these birds is known to depend on ever-disappearing "islands" of trees and shrubs that still exist in an otherwise developed landscape. This area, including the island, probably is such a stopover point, and one whose value increases as more development occurs elsewhere.
The mainland includes 6 wetland areas which, although "adjacent" by regulatory definition, do not directly abut the waterway or adjacent wetlands. These areas are "distinct" in that they perform different functions and values than the open marshlands and their abutting and more fully contiguous wetlands. These are primarily fingers or pockets of wetlands within the mainland primarily surrounded by upland; two of these pockets have direct, but narrow connections to areas which we are considering Humbug Marsh. The pockets of wetlands integrated throughout the uplands on the mainland are not being considered part of "Humbug Marsh". The upland portions of the site are not considered Humbug Marsh, though they do contribute to the functions and values of the marsh and river. It is recognized by the regulatory and scientific community that vegetated buffers, including uplands, adjacent to open waters provide many of the same functions and values as wetlands (See WES report and "Vegetated Buffers" discussion within the Proposal to Modify Nationwide Permits, Federal Register Vol 64 No 139, Encl 41).
In accordance with a mitigation agreement negotiated between the Michigan Department of Natural Resources (now acting as MDEQ), the USEPA, and Waste Management Inc., approximately 112 acres of the site are included in a conservation easement. Approximately 101 acres of the easement is open water and marsh. The remainder of the easement area, approximately 11 acres, is an upland buffer generally 60' wide.
The unique combination of the shallow, open water marsh, the vegetated shelf, the undeveloped island with diverse transitional habitats including a substantial stand of large trees, and the undeveloped mainland, which also provides habitat diversity and large trees produces a unique, interrelated, interdependent habitat. This combination is expected to be sensitive to disturbance.
According to the MDEQ record of decision, the Michigan Natural Features Inventory (NFI) determined that the site might contain habitat for the state threatened small mouth salamander and the king rail. The NFI determined that the survey conducted by the applicant's consultant for the small mouth salamanders was conducted at the wrong time of the year and that the submitted survey was inadequate.
The wetland/bottomland complex of the Detroit River is navigable and is used by fishermen. Depending on water levels, boat access to the wetland complex is from both north and south of the island. Fisheries sampling has revealed large numbers of game and forage fish species in the wetland complex.
Taken together, the site afforded a large, relatively undisturbed area of second growth uplands, several types of wetlands, shallow water riverine habitat, slackwater drains and streams, intermittent streams and drainageways, a forested mainland and island riparian shoreline, and other habitat niches. Such an area exists nowhere else on the U.S. mainland side of the Detroit River.
Region 3, U.S. Fish and Wildlife Service
1 Federal Drive
BHW Federal Building
Fort Snelling, MN 55111
E-Mail Us!
R3 External AffairsDr. John H. Hartig, Refuge Manager
Detroit River International Wildlife Refuge
Large Lakes Research Station
9311 Groh Road
Grosse Ile, MI 48138
Phone: 734-692-7608 Fax: 734-692-7603
E-mail: john_hartig@fws.gov
Last updated:
July 9, 2008
|