Floating Wetlands, Coming to a Bay Near You?

Image of potential Lake Merritt floating wetlands
A visualization of the potential floating wetlands that could soon be installed in Lake Merritt. Courtesy of the City of Oakland.

We were excited to hear earlier this month about an innovative new project to tackle water pollution and habitat loss in heavily impaired waterways: human-constructed islands of floating wetlands.

Community groups in the City of Baltimore recently installed these floating wetlands in the city’s highly-urbanized inner harbor. Made out of previously-littered plastic bottles collected from the harbor itself, the volunteers planted 2,000 square feet of floating islands with native marsh plants, launching them into a waterway that is too polluted for human contact 73% of the time. (Click here to watch a video of Baltimore’s floating wetlands being installed in the Chesapeake Bay)

The marsh plants will help to filter pollutants out of the water and provide habitat for a variety of species including crabs, mussels, herons and perch. Beyond these benefits, the floating wetlands provide an invaluable educational tool to the community. They remind residents what the shoreline used to look like, and that the Bay is not just a place for cigarette butts, plastic bags, and car oil – but an ecosystem that needs our help and attention.

Next Stop: Oakland’s Lake Merritt?

We know that protecting our shorelines from development and restoring them back to naturally-functioning tidal marsh should always be our priority. Unfortunately, there are some areas of the San Francisco Bay that are so significantly altered – with tidelands paved over by urban development, and the ecosystem highly polluted and degraded – that options for habitat creation are limited.

One of those areas is Oakland’s Lake Merritt – a tidal lagoon that is in the midst of an impressive effort by the City to reconnect the waterway with the Bay, restore tidal marsh and improve public access and park space.

The natural marshes along the Lake’s shoreline have long since been filled in with roadways, housing, offices, a convention center and more. The channel connecting the Lake to the Bay had been narrowed considerably over the past century, with the tides eventually forced through a series of culverts, further constricting flows. Perhaps most damaging, 62 storm drains, from throughout Oakland, were routed directly into the Lake, bringing with them car oil, trash and other pollutants from the city’s streets. The result: what had once been the first wildlife refuge in the United States in 1870, became listed by the Environmental Protection Agency as an “impaired water body” in 1999.

Since then, the City of Oakland has worked hard, alongside dedicated residents and the Lake Merritt Institute, in improving the health of the Lake. Several large water fountains were installed to get more oxygen into the water to support aquatic species. The City, thanks to local funding approved by Oakland voters, has completed an historic project to take out the old culverts, widen the channel connecting the Lake to the Bay, re-design the nearby roadways to slow traffic and increase parkland, and carve out 3 acres of new wetlands. (Click here to read our blog on the history of Lake Merritt and learn more about the major projects underway)

However, future wetland restoration around Lake Merritt is limited by the highly urbanized shoreline – the fact that so much of the former mudflat and tidal marsh areas have been filled in and developed.

Rather than let the constraints stop continued progress on bringing back the health of the Lake, staff with the City of Oakland are currently designing a large track of floating wetlands –similar to those developed in Baltimore’s Inner Harbor – to be installed in the Lake in years to come. While staffers are still determining the size, plants and anchoring material, early visualizations show a long, curved expanse of marsh, floating along the shoreline of the Lake near stormwater outfalls.

Rebecca Tuden, Watershed Specialist with the City of Oakland, notes that they are currently looking at this as a pilot program, which should provide benefits to water quality including improved oxygen and the uptake of harmful pollutants that make their way to the Lake from city streets. The floating wetland would also offer habitat for benthic species – critters at the base of the food web that support fish, birds and other wildlife.

While floating wetlands will never replace the need to restore our natural shorelines, we are encouraged by their potential benefits to water quality and species at the base of the food system, and most importantly, the educational value they provide for local communities. If we can begin to think about our local waterways as an exciting ecosystem full of opportunities for improvement, rather than a trash-filled cesspool, that will make a big difference for what our Bay’s future looks like.

This Sunday, the City of Oakland is teaming up with the Measure DD Community Coalition, Walk Oakland Bike Oakland, the East Bay Bicycle Coalition and others to organize “Love Our Lake Day” – a celebration of the grand opening of the new trails, wetlands, and re-configured roadways at Lake Merritt. 3 miles of streets around Lake Merritt will be closed to car traffic, allowing walkers and bikers to enjoy the improvements to the area. Visits www.LoveOurLakeDay.com for more information, and make sure to stop by the Save The Bay table in Snow Park!