Lake Jackson’s ‘Created’ Wetland

Multi-use stormwater treatment parks are being designed across the PanhandleLake Jackson’s ‘Created’ Wetland An Attractive Solution to Managing Stormwater Runoff

By Faith Eidse

When you think of a stormwater pond, the mental vision is usually a muddy hole in a back lot surrounded by a chain link fence that attracts few contented visitors – human or otherwise – swimming, crawling, flying, walking or otherwise enjoying the scenery.

But across the Panhandle, the Northwest Florida Water Management District is designing multi-use stormwater treatment parks that feature recreation trails, waterfalls and channels winding through blooming marsh grasses.

The district’s latest design is an inviting wetland park near Lake Jackson that one day may be linked by a trail to the Lake Jackson Mounds Archaeological State Park. Visitors to the Okeeheepkee Prairie Regional Stormwater Management Facility will be able to observe wildlife and stormwater treatment at work as runoff filters through a forebay pond (a settling pond that traps trash and sediment before it can reach the wetland, it’s simpler to clean out than the wetland), a waterfall, a deep pool and winding channels. This “created” wetland between uplands and open water also offers food, shelter and water for birds, amphibians, reptiles, fish and insects.

The $1.3-million facility, funded through a $600,000 contribution from the Northwest Florida Water Management District and other funding from Leon County, will help cleanse stormwater runoff from Monroe Street north of Interstate 10, within the Okeeheepkee sub-basin of the Meginnis Arm watershed, before it reaches Lake Jackson.

The planned trail, it turns out, may have been part of a network of trails that existed in prehistoric times. This general area of the Lake Jackson shoreline offers the only known evidence in the region of a prehistoric farmstead or living area in the bottomlands near the mounds complex. The water management district has worked with the Florida Department of State’s Division of Historical Resources to ensure significant cultural resources will be protected and preserved.

Grady L. “Lee” Marchman, chief of the district’s Surface Water Bureau, conceptualized the stormwater garden in Lake Jackson’s basin to close a gap in treating the lake’s biggest polluter – stormwater runoff.

“You’ve got to have (stormwater facilities) anyway. Why should they be eyesores?” he said.

The facility will capture and settle out fertilizers, pesticides, greases, oils, sediments and trash before they reach a lake that has no surface water outlets.

Lake Jackson’s peculiar natural cleansing feature is its periodic draining, or “drydown,” into two active sinkholes, Lime Sink and Porter Hole Sink. Sinkholes are created when underlying limestone dissolves beneath the red clay soils of the Tallahassee hills. This results in many deep or shallow lakes within the larger basin; such lakes often collapse to form sinkholes and connect to the underlying aquifer through underground channels. Drydowns may frustrate boaters and lakefront homeowners, but they benefit the lake by oxidizing contaminants and limiting excessive plant growth.         

Throughout recorded history, the lake has drained approximately every 25 years, sometimes refilling and re-draining over several months or years in a row. A rapid, overnight draining was described in the winter of 1837, and the lake disappeared suddenly following the Charleston, S.C., earthquake of 1886. During the 20th century, the lake at least partially drained through sinks from 1907 to 1909, from 1932 to 1936, from 1956 to 1957, from 1982 to 1983 and from 1999 to 2001.

In fact, the mound builders who flourished on Lake Jackson’s shores as early as 1050-1500 A.D. called the lake Okeeheepkee (pronounced “OH-kuh-HEEP-kee”), meaning “disappearing waters.” During some drydowns, the lakebed was cultivated and cattle grazed in its bottomlands. Three saddles, or ridges, that divide the lake into four sub-basins were used as high ground for cattle crossings.

Without drydowns, as well as the concerted efforts of federal, state and local agencies, Lake Jackson might be known today as Jackson Marsh – a rapidly aging swamp filled in due to development in its watershed. Substantial efforts over the past 25 years have helped slow this process by retrofitting, with stormwater treatment facilities, an urban basin that grew with few runoff controls and water-quality protections in place.  

In September 1999, when it appeared that the southern portion of the lake would go dry, the Northwest Florida Water Management District organized a technical advisory committee and oversaw permitting and design phases of an $8-million muck removal process, with the bulk of the cost borne by Leon County. The Florida Fish and Wildlife Conservation Commission, Florida Department of Environmental Protection (DEP) and state Legislature also contributed. Two million cubic yards of organic muck some three feet deep were dredged from urbanized inflows. Since that time, the lake has come back with greater clarity and improved natural habitat.

The first muck removal took place in 1992, 20 years after substantial construction in the watershed, including Interstate 10, U.S. Highway 27 and several malls, had filled the lake’s Meginnis Arm with vast amounts of sediment. The $1-million restoration dredged more than 100,000 cubic yards of degraded sediments. That effort was funded primarily through the water management district’s Surface Water Improvement and Management program, Leon County, the City of Tallahassee, the DEP and the U.S. Environmental Protection Agency (EPA).

Prior to the effort, in the late 1970s and early 1980s, the water management district designed and constructed an award-winning treatment demonstration project in the lake’s Meginniss Arm basin to reduce contaminated runoff from the North Monroe Street business corridor south of Interstate 10. Easily seen from the interstate, the Lake Jackson Stormwater Treatment Facility was one of the first to use detention with filtration to treat stormwater runoff. It intercepts runoff from streets and parking lots and settles out heavy sediments at its deep end. As the pond fills, stormwater flows through the sand filter, which strains additional particulates. Treated water discharges at the base of a 10-foot dam, where it flows to a manmade, three-cell marsh. It then flows into the lake, cleansed of most of its pollutants. Funded and built with assistance from Leon County, the EPA and the DEP, the facility has resulted in reduced nutrient concentrations, improved oxygen levels and enhanced habitat.

The district built a second pond when it determined that untreated stormwater from I-10 and Lakeshore Drive was mixing with partially treated runoff from the stormwater facility. The Meginnis Creek Pond Facility was completed in 1993 and funded by the district, the Florida Department of Transportation and Leon County. Other projects in the lake basin have included stormwater retrofits within the city and county. In addition, the district has proposed restoring and enhancing 17 acres of native shoreline vegetation in Meginnis Arm. Leon County and the DEP also have worked to control plants within the lake and along the lakeshores.

Further extensive retrofits continue, including products located immediately upstream that are being developed by Leon County and the city of Tallahassee. These are funded in part by the Florida Forever Capital Improvement Grant Program, administered by the Northwest Florida Water Management District.

Many informed homeowners around Lake Jackson also are trying to be part of the solution. They limit the use of fertilizers and pesticides on their lawns and plant native species, which tolerate drought, insects and disease better than do most non-native species. Water-permeable paver blocks, porous pavement and grassy parking areas used in some Lake Jackson basin parking lots also permit seepage and filtration.

The next wave in stormwater treatment – wet detention ponds, artificial marshes or treatment wetlands – has arrived. Visitors soon will be able to observe the process at work preserving Lake Jackson, Tallahassee’s primary historical and recreational attraction.