Filter Island

In the 1909 Plan of Chicago, Daniel Burnham sought to harmonize two physical systems that had always been incom­patible along Chicago’s lakefront: transportation and recreation. Re-envisioned transportation networks included railroads to be realigned, roadways to be built, and harbors to be located. Simultaneously, in the same space, Burnham envisioned a continuous lakefront recreational park filled with new public buildings and amenities. Synthesizing technical necessities with cultural enhancements ultimately produced a lakefront that was much more than the sum of its functional parts.

A decade before Burnham’s Plan, engineers transformed the Chicago River into a model of water management and transportation infrastructure. Directing the flow of the river away from Lake Michigan and linking it via canals to the Mississippi River was critical for the health and prosperity of Chicagoans. It still is, but Chicago has changed.

Today, Chicago faces new challenges to its physical form. On a semi-regular basis, massive rainstorms overwhelm the Chicago River, which leads to raw sewage overflowing into Lake Michigan. Additionally, the river has become a two-way conduit for invasive species. These invasions cause billions of dollars a year in damage to water infrastructures and ecosystems from Lake Michigan to the Gulf of Mexico.

We believe it is time to redesign the river and while we’re at it, leverage the redesign to conceptualize new civic possibilities. Our project—Filter Island—springs from Chicago’s legacy of leveraging infrastructural improvements to simultaneously create new civic space. The first step toward this double-goal is to dam the Chicago River near the confluence of its three branches: the North Branch, the South Branch, and the Chicago River. By damming the river, three branches (operating as one waterway) transform into two separate waterways: the new South Branch and the new Chicago River. The new Chicago River flows between two mouths of Lake Michigan: the southern mouth in downtown Chicago and the northern mouth in Wilmette, Illinois. The existing locks are removed between river and lake resulting in the new Chicago River becoming an extension of the lake.

Damming the river will halt the transmission of invasive species and prevent yearly losses of billions of gallons of Lake Michigan water currently leaking through the existing locks. But, damming doesn’t fix the whole problem. Currently the river acts as an overflow for stormwater and sewage during severe rainstorms. Because the river will once again flow into the lake, a new approach is needed to remove dangerous toxins and microbes.

Filter Island cleans the new Chicago River by filtering pollutants in a series of large scale bio-cells. Polluted water flows into Filter Island over a shallow waterfall at the northern edge of the new island. Through a series of wetlands and bio-pools polluted water is cleaned of contaminates before being discharged into the lake. The ratio of water cleansing landscape to park program landscape flips as the park extends southward. Park programs range from ecological wetlands, marshes, and fields to cultural programs such as swimming pools, water parks, sports courts, and playgrounds. The whole island is wrapped in a programmed edge that includes beaches, pathways, and break waters.

To accommodate boat traffic between the river and lake, there is a new dry-dock transfer exchange along the eastern extension of the new Chicago River.

Rather than hide the water cleaning process, Filter Island reveals it. Rather than employ a heavy industrial, energy intensive system, Filter Island is a passive, low-energy water treatment sponge. But most vitally, Filter Island is a hybridized landscape combining the transportation of water with new recreational spaces.