Harris County tests floating vegetated islands to help clean waterways

HARRIS COUNTY, Texas (KTRK) -- Harris County commissioners voted on Thursday to partner with University of Houston researchers to study floating vegetated islands designed to improve stormwater quality at a county detention basin.

The islands are located at the Stormwater Detention Basin at Reverend William and Audrey Lawson Park. The Harris County Flood Control District said they were installed there this past spring.

Above the water, the islands appear to be just plastic and plants floating. But the flood control district said what happens below the surface could help keep pollutants out of stormwater before they reach local bayous and waterways.

"We just wanted to test some other tool in the toolbox that can help us remove the stormwater pollutants, and these floating vegetated islands could be that for us," Harris County Flood Control District Environmental Services Department Manager Jonathan Holley said.

According to Holley, the islands are made of recycled plastic with holes filled with native wetland plants. The roots dangle underneath into the water.

"Those roots are where the magic happens, where the pollutant uptake, the removal of sediment and nutrients and other stormwater pollutants happen," Holley said.

The three-year study will cost more than $500,000, according to the flood control district. Holley said a majority of that is funded through a Texas Commission on Environmental Quality grant, with the rest covered by a 2018 Flood Control Bond.

Holley said the study will include monitoring water quality and pollutant removal, as well as tracking how the vegetation develops and what maintenance is needed to keep the islands working.

"We do expect we'll learn some things and understand how they perform with removing those stormwater pollutants and then apply it hopefully to other places where it's applicable and can work well," Holley said.

The long-term goal, according to Holley, is to determine whether the islands could be used at flood control detention basins across the region.