Why the Jordan Marsh Water Quality Treatment Park is so cool

The Sanibel Slough, known to most of us as the Sanibel River, feeds fresh water into low-lying swales to create Sanibel's interior wetland system. As a result, the health of the Sanibel Slough is critical to the health of those wetlands and hence to the health of the wildlife that inhabits the J.N. "Ding" Darling National Wildlife Refuge. Unfortunately, more than a decade ago, the slough was identified by the Florida Department of Environmental Protection as being impaired for nutrients, meaning that it does not meet state standards for nitrogen and phosphorus. But we will describe a very cool project that is helping to reduce the nutrient concentrations in the slough.

The somewhat recently opened Jordan Marsh is a filter marsh, one side of which abuts Casa Ybel Road. The creation of the marsh was funded by the South Florida Water Management District, Lee County impact fees, and the city of Sanibel. A pump located at the rear of the property pulls water out of the Sanibel Slough. The water meanders throughout the marsh before it is returned to the slough. Within the marsh, plants such as cattails, bulrush, and pickerelweed, remove excess nutrients.

If the water is pumped into the marsh at a low rate, it spends a lot of time there, and hence the marsh removes a high percentage of the nutrients. In contrast, if the water is pumped in at a high rate, it spends less time in the marsh and as a result, a lower percentage of the nutrients are removed. However, there is a tradeoff. Since the water spends less time in the marsh, it is possible to pump more water through the marsh and hence the marsh can potentially remove a larger amount of nutrients.