Floating Islands—An Alternative to Urban Wetlands

Abstract

The creation, enhancement, and restoration of wetlands in the urban setting pose a suite of challenges including space constraints, sediment contamination, upstream pollution sources, and compromised water quality for wetland practitioners. These challenges are amplified in situations where the wetlands are dominated by fluvial systems (e.g., streams, rivers). Here we discuss the installation of seven floating islands in a highly impacted (polluted) part of the tidal Anacostia River, adjacent to Diamond Teague Park, Washington, D.C. Floating islands (also called floating wetlands) are based on natural phenomena and have been used to improve water quality in many parts of Asia. However, they are only just being considered as viable wetland creation options in the United States. Although the surface area of the seven floating islands is small, measuring slightly over 1,600 square feet, the roots floating in the water column provide an equivalent wetland area of six acres. The nitrogen, phosphate, and ammonia that these floating islands have been designed to remove from the Anacostia River annually are 990, 138, and 990 pounds, respectively. In addition to improving water quality, these wetlands create valuable wildlife and aquatic habitat. Floating islands provide an innovative opportunity in urban areas where issues such as water quality, site constraints, aesthetics, community needs, and costs need to be considered.