In Dubuque, Iowa, city officials spent $176,000 on an unusual urban experiment: 14 floating islands made partly from thousands of recycled plastic bottles, according to an online report by IECA News. Rather than relying solely on concrete, bigger pipes, or taller walls to fight recurring flash floods, the city turned to nature-based infrastructure to protect the local watershed.
Daylighting Bee Branch Creek to Combat Flooding
Flooding has long plagued the 7-square-mile Bee Branch Watershed, where more than half of Dubuque’s residents live or work, according to the IECA News report. Repeated flash floods damaged roughly 1,300 homes and businesses, wreaking widespread havoc on buildings, roads, and stormwater infrastructure. To fix the issue, the city daylighted the Bee Branch, a creek that had been buried in a storm sewer for about a century. Reintroducing the waterway to the surface allowed planners to weave natural features directly into their flood mitigation strategy.
Building Islands From 67,000 Recycled Water Bottles
The resulting 14 islands span a total of 2,674 square feet and act as miniature replicas of natural Mississippi River archipelagos, as detailed by IECA News. Before placing them in the creek, project organizers developed four prototype designs in various shapes and sizes. Crews constructed the primary floating structures using approximately 67,000 recycled BPA-free water bottles. They added native plants and carefully chosen pieces of driftwood to build year-round habitats, while fencing protected the new greenery from local waterfowl.
Pro Tip for Urban Planners: Flexible anchoring systems using stainless-steel cables allow floating islands to shift naturally with changing water levels and flow directions, minimizing structural stress during high-flow events.
Ecological Functions and Water Quality Improvements
These floating gardens perform several vital ecological functions beyond basic aesthetics. According to the IECA News report, the structures interrupt wave energy to reduce erosion along the creek edges. They also act as barriers that slow moving water, allowing suspended sediment to settle and keeping the water clear. Plants on the islands absorb excess nutrients like nitrogen and phosphorus, keeping those elements out of waterways and reducing the risk of downstream ecological problems in the Mississippi River and Gulf of Mexico.
Beneath the surface, plant roots and floating structures host biofilms—microorganisms that help break down pollutants. Roots offer shelter to fish and juvenile aquatic species, while insects and crustaceans utilize the vegetation as part of the wider food web. Birds also rely on the islands above the water for resting and potential nesting habitat.
Maintenance and Long-Term Ecosystem Health
Nature-based infrastructure requires diligent, ongoing upkeep, as demonstrated by the Dubuque project. Crews regularly inspect the islands to check buoyancy, vegetation health, and anchoring systems. A 2019 inspection revealed that while most plants thrived, some required replacement following animal interference, and parts of the protective fencing needed repairs.
Did You Know? The Bee Branch Creek restoration project was partially funded through a combination of grants and donations, keeping municipal costs managed while establishing a working model for urban ecology.
Frequently Asked Questions
How much did the Bee Branch Creek floating islands cost?
The project cost $176,000 and was partially funded by grants and donations, according to the IECA News report.
What materials were used to build the floating islands?
The primary floating structures were constructed from approximately 67,000 recycled BPA-free water bottles, combined with native plants, driftwood, protective fencing, and stainless-steel anchor cables.
How do the islands prevent flooding and erosion?
The island structures interrupt wave energy to reduce edge erosion and act as physical barriers that slow water down, which allows suspended sediment to settle and keeps the creek clear.
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