ILLINOIS BEACH STATE PARK
One of the last natural shorelines in the state, Illinois Beach State Park is located on the Zion Beach Ridge Plain, a slowly migratory complex that has shifted southward over thousands of years through erosive and accretive processes. The strong northeastern waves erode the northern portion of the ridge while the southward littoral drift transports and deposits the sediment in the south. Overtime, these processes have built up the unique curvilinear ridge-and-swale topography that supports a variety of habitat including, the upland black oak savanna and the panne wetlands. This dynamism has been challenged by anthropologic changes and uses of the park, specifically the North Point Marina and the Waukegan Harbor, which bookend the park on either side. The marina blocks the southern movement of sand and creates a sediment starved portion in the northern end of the park, while the breakwaters and navigation channel in the Waukegan Harbor intercepts the sand, and halts the southward movement of the ridge plain. Lake Michigan’s current near record high lake levels have further increased the northern units’ high level of erosion, causing a loss of up to 60 feet per year. Highly erosive areas threaten public access, roads, buildings, and important ecological areas. While in the past, the park has responded through feeder beaches supplied by the dredged sediment in the Waukegan navigation channel, these beaches have quickly eroded, often in the course of a few years. Currently, the park has in motion a plan to fortify identified sites of high importance with a series of tuned emerged breakwaters. While breakwaters are justifiable in particular situations, their cost and labor intensive nature make them less applicable as elsewhere, making a case for alternative strategies to be explored.
Our project explores alternative coastal interventions to slow down the erosion of the beach and the movement of sand. It seeks to implement an intervention that acknowledges and works with the regional sediment dynamism characteristic of the area. Finally, rather than “holding the line” of the shoreline, it recognizes the cyclical highs and lows of the lake, and expands the focus to the entirety of the ridge-swale shore zone, an area spanning the bar breaker zone to the dune face. How will the design work with and add to the topographic and bathymetric complexity that defines the lacustrine shore?
To explore these questions, our team, partnered with IDNR, AnchorQEA, and a coastal geologist, Ethan Theuerkauf, from Michigan State University, will design and implement a pilot project. This project will involve selecting a study site, developing data collection system, and designing and implementing the pilot project feature.
1. DYNAMISM: A recognition of the geologic migratory ridge-swale complex and the cyclical water levels in the lake that contribute to a rich and topographically complex system.
2. EXPANSION OF RIDGE AND SWALE: An expanded focus beyond the shoreline, which includes the varied and important habitat types that inhabit the ridge-and-swale shore zone.
3. SLOW NOT STOP: An emphasis on choosing less measures to slow the erosive processes with a recognition that the design intervention is for a medium range of conditions, not the extreme.
4. DESIGN RESEARCH COLLABORATION: An effort to learn from and gather information for implementation of other future projects.