Urban Waters

Gateway to Improved Long-term Spawning (GILS)

Developed in partnership with Marek Landscaping and the UW - Milwaukee School of Freshwater Sciences, the GILS program is responsible for the installation, maintenance, and monitoring of the GILS Floating Islands to provide food and shelter to fish in their natural habitat. The GILS Floating Islands are attached within the corrugations of steel bulkheads and contain a variety of wetland plants that young fish use for food and shelter. Unique engineering designs have been developed to reflect wall conditions, water quality, freeze/thaw patterns, ice and wave action, tolerant vegetation, and target species needs.

A team of local fisheries and habitat experts along with Groundwork Milwaukee installed four GILS Floating Islands to introduce quality habitat for fish along the shipping channel of the Milwaukee River Estuary. The riverbanks of interest within the channel are lined with vertical steel sheet walls, retaining walls, concrete, and steel bulkheads to provide structural stability and eliminate erosion from passing barges. It is impossible for fish to survive in these areas of the river due to dredging and lack of vegetation to support them.

GILS Program Goals and Objectives:


The GILS program’s long-term goals are to improve aquatic habitat availability, increase fish population, and improve spawning patterns along the shipping channel of the Milwaukee River Estuary. Short-term project goals include:


• Identifying potential installation sites
• Selecting plant species
• Determining alternative plant rearing facilities & techniques
• Finalizing locations and bolstering project interest.
• Determining alternatives for attachment mechanisms, flotation containers, soil and plants; choose best method
• Fabricating attachment device
• Establishing plant nursery and begin incorporating plant-rearing techniques
• Determining the best statistical methods to evaluate fish use of the structures
• Determining winter die off rate in GILS Floating Islands, spring re-sprout rate of plants and use by fish species.
• Monitoring of GILS Floating Islands for plant vitality, basket maintenance, and fish use
• Developing recreational and aesthetic surveys
• Placing fish & assemblage data in the MMSD/USGS historical database


Project Funders

Project Partners