Restoring connectivity between Powderhorn Lake + Wolf Lake brings marsh birds together
Key marsh birds like the Black-Crowned Night Heron and the Pied-billed Grebe rely on a healthy hemi-marsh to thrive
Hi TWIB! My name is Emily and I’ve been writing about how our urban habitat can become more hospitable to natural flora and fauna for many years. This week, I am contributing a piece about how controlling water levels among Powderhorn Lake, Wolf Lake, and the critical marshland in-between will help create a more supportive environment to the wealth of marsh bird populations that call the Calumet section of Chicago home.
The Powderhorn Lake + Wolf Lake Restoration Project aims to unite the 50-acre freshwater lake and its adjacent 55-acre shallow pool with the 950-acre Wolf Lake. The purpose of this project is to improve circulation and drainage between these aquatic systems with the Great Lakes system, lowering troublesome water levels and supporting the natural habitat of the area’s marsh birds. These bodies of water lie in southeast Chicago’s Calumet region, an area populated by steel mills and industrial activity at first blush, but which is naturally supportive to a rich marshland ecosystem, and remains one of the few, and most high quality, examples of Illinois’ dune and swale topography.
The dunes, as they are known in Chicagoan parlance, were formed by the melting of a massive ice shelf some 11,000 years ago, and exist alongside their counterpoint: low-lying swales, which are water-filled trenches between the dunes. The dunes are a sight to behold in and of themselves, and form some elevational interest amid the area’s generally flat appearance. Along with the marsh habitat, which consists of low-lying wetlands, these ecological features provide important refuge, breeding grounds, sources of food, and other key benefits to supporting the incredible wealth of bird species in the area—nearly 300 species in all.
The key to a healthy marsh is just enough water, and the principal issues that have plagued the Powderhorn and Wolf Lake ecosystems have resulted from the current, long-standing high-water conditions, which were brought about by industrial and residential development, causing a segmentation of the habitat. According to Chip O’Leary, Deputy Director of Resource Management, Forest Preserves of Cook County, the water levels have been elevated—e.g. flooded —for decades, with no real reprieve. The high water conditions pose a flooding risk to the railway adjacent to Powderhorn Marsh and nearby neighborhoods, as well as making it difficult for marsh birds to thrive.
The reasons that majority sustained high-water conditions are not an attractive habitat for marsh birds are multitudinous. High water means little opportunity for fish habitats where the lack of shallows prevents younger fish from being spawned and raised. As many marsh birds primarily subsist on fish, this factor makes it difficult for them to nest nearby. Another important food source for marsh birds are aquatic insects, which can’t survive in deeper open waters. Additionally, without lower water levels to support marsh grasses and vegetation, the ability for birds to take refuge, raise young, and hide from predators is greatly reduced.
Take for instance, the Black-Crowned Night Heron, a stocky, more crepuscular North American heron, which, like its brethren, survives primarily by foraging in the shallows for fish, frogs, and other aquatic creatures with its graceful streamlined beak. Another bird species recorded in the Calumet region, the Pied-billed Grebe builds its floating nests out of cattails, marsh grasses, and other wetland vegetation, which work as both a construction material and a visual barrier to keep its eggs safe from predators.
In order to support the delicate ecosystem birds like the Black-Crowned Night Heron, the Pied-billed Grebe, and many more rely upon, the Powderhorn Lake + Wolf Lake Restoration Project aims to restore critical habitat by installing a water control structure at the north end of Powderhorn Lake. The structure will allow Powderhorn Lake, which suffers from low-quality fish life, to drain into Wolf Lake, which supports a much healthier fish habitat, connecting the two habitats and providing a safe passage for fish, and ultimately boosting the health and resilience of the entire aquatic system.
Importantly, it will also allow water managers to raise and lower water levels of the shallow pool adjacent to Powderhorn Lake in order to maintain the hemi-marsh conditions, defined as a highly interspersed mix of open water and emergent vegetation. This will improve the health and quality of the wetland habitat, support fish spawning and thus a key food source for marsh birds, and reduce the risk of neighboring erosion and flooding due to stormwater run-off. The result will provide many benefits for both the ecosystem and surrounding communities.
The Powderhorn project is funded by the Great Lakes Restoration Initiative through a regional partnership among Audubon Great Lakes, the Forest Preserves of Cook County, National Oceanic and Atmospheric Administration (NOAA) and the Great Lakes Commission (GLC), and its timeline is approximately three years. You can learn more here.
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Images of Powderhorn Lake: Audubon Great Lakes.
Black-Crowned Night Heron. CC-BY-SA. Charles Homler d/b/a Focus On Wildlife