A Milestone for the
Everglades Restoration Plan

For the paddler winding his canoe through the gentle, tree-lined waters of Ten Mile Creek in southeast Florida, there is little to mark this small tributary to the St. Lucie River as something special.

Yet this fall, the eyes of engineers and environmentalists across the country will be focused on the creek and its adjacent preserve. Here, a new reservoir and created wetland stormwater treatment system will become the prototype system for larger reservoir projects integral to the nation’s Everglades restoration and the future water supply needs of central and south Florida.

A Critical Project

The importance of the Ten Mile Creek restoration effort was flagged nearly a decade ago, when it was one of nine “critical projects” authorized by the United States Congress to provide immediate benefits to the central and south Florida ecosystem. The creek contributes almost 25 percent of the flow to the north fork of the St. Lucie River and feeds into the Indian River Lagoon, an Outstanding Florida Water and one of the most biologically diverse estuaries in North America.

As much as 150,000 acre-feet of excess water is discharged into the St. Lucie River annually. By attenuating summer stormwater flows and improving the quality of water from Ten Mile Creek, the U.S. Army Corps of Engineers and its local partner, the South Florida Water Management District, expect to positively impact the Indian River Lagoon, which is considered endangered from the excessive freshwater flows. At the same time, they will apply the lessons learned to other projects that will be built throughout south Florida and the Everglades system as part of the Comprehensive Everglades Restoration Plan (CERP).

How It Works

Today, all of the flow from Ten Mile Creek feeds into the north fork of the St. Lucie River. But this fall, when the Ten Mile Creek Water Preserve Area is completed, water managers will be able to begin diverting some of the water into a 550-acre, above-ground reservoir capable of holding nearly 2 billion gallons of water. A station with three pumps with a total capacity of 380 cubic feet per second (cfs) provides flexible water lifting for the project during a variety of high-flow conditions in the creek. Once in the reservoir, suspended sediments will settle as the water moves through the system.

PBS&J provided design services for the project. According to the firm’s project manager, Blake Guillory, P.E., “From this reservoir, water will then flow into an adjacent stormwater treatment area via a gravity control structure where pollutants—nitrogen and phosphorous—are filtered out as water moves naturally through the system.” When gravity flow from the reservoir to the treatment area is not possible, a second 40-cfs pump station will allow water managers to meter the flow of water from the reservoir to the wetland treatment system through a 50-foot-long, 11-gate distribution structure. The distribution system is designed to simulate an 18-inch-deep sheet flow of water through wetlands. The wetland treatment system will improve water quality by filtering out excess nutrients from stormwater before it enters the St. Lucie Estuary and Indian River Lagoon.

While water quality improvement is the key objective of the Ten Mile Creek Water Preserve Area, the local community will find additional benefits from the project. St. Lucie County has recreational plans for the area, including providing opportunities for hiking, wildlife viewing, canoeing, and fishing.

A Model for Other Restoration Projects

Other similar projects—some 20 times as large as this one—are planned as part of the Everglades restoration efforts. Lessons learned from the Ten Mile Creek project can be applied to these projects, according to Guillory. “For example, a large cost to the project is the hauling of dirt from one area of the project to another. Evaluating methods to reduce the movement of dirt was a big consideration in the cost estimating process. In addition, wave action from high winds could cause significant erosion of the levees, so we opted to armor the inside of the levee with soil cement instead of rock, which is very expensive to haul to this location. While we know that each project will have unique challenges, some of the ‘lessons learned’ on this project will certainly benefit future efforts.”