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County begins dredging project at Lake Seminole | Pinellas County

SEMINOLE — Pinellas County recently began what it is calling the “most important phase” of the Lake Seminole Restoration Project.

A county contractor, Clearwater-based Gator Dredging, has started a dredge operation that will remove about 900,000 cubic yards of organic sediment from the lake. The goal is to bring it the lake to its healthiest state in decades.

Accumulated sediment has contributed to water quality problems and habitat degradation. The three-year dredging operation will remove about 54 tons of phosphorus and 311 tons of nitrogen, reducing nitrogen loads by 56% in Long Bayou and Boca Ciega Bay.

The $19 million project is expected to be complete in early 2023. It began in August 2018.

“This project will reduce the available nutrients for algae and vegetation growth,” said Pinellas County Senior Environmental Specialist Rob Burnes. “We’ll have cleaner water, a healthier lake bottom, more fish, fewer invasive plants, more native plants and a much nicer lake.”

Gator Dredging is using a hydraulic dredge to remove the muck from the bottom of the lake. The muck will be transported to a Dredge Material Management Area on county-owned land between Lake Seminole Park and the Cross Bayou Little League Fields.

The materials will sit on the 20-acre site to “dewater and consolidate.” Eventually, the area will form a berm that can be used for parkland or ball fields.

This is not the first project the county has undertaken for Lake Seminole. Considered an “impaired waterbody” due to elevated levels phosphorous and nitrogen in the lake, the county has been working to improve the water quality since it began to decline in the late-1980s. It has been a constant battle to keep the water clean, keep the fish stocked and combat the growth of nuisance aquatic plants.

The Lake Seminole Restoration Project is part of the Lake Seminole Watershed Management Plan adopted in 2004 to improve the water quality.

The lake was lowered and the muck removed in 2005. In addition, over the years, the county built regional stormwater treatment facilities, implemented bypass canal treatment and diversion. It also did a shoreline restoration project, restored priority wetlands and installed a gauging station.

The county says one of the most important improvements thus far has been the addition of four “Alum” stations that reduce nutrient inputs into the lake by capturing urban stormwater before it enters the lake and treating it with aluminum sulphate.

County officials say that the water quality of the lake is improving. Nitrogen and phosphorous levels are going down. Chlorophyll is decreasing. Water clarity is improving. But, the nutrient levels are still too high.

The dredging project is the No. 1 recommended method to try to reduce the levels and continue improving water quality.

The lake restoration project is funding by Penny for Pinellas, Southwest Water Management District, a state appropriation and the RESTORE act.

History of the lake

County commissioners passed a resolution on July 3, 1945, to create a freshwater lake in conjunction with the planned construction of Park Boulevard and a causeway across Long Bayou.

The lake was built on an arm of Long Bayou, a brackish water segment of Boca Ciega Bay. The area was flooded with freshwater from Long Creek, but it was filled with centuries-old muck sediments that had accumulated in the poorly flushed backwater. That sediment is continuing to create problems today

Over the years, changes were made in the design and placement of the structures used to contain the fresh water in the lake. In the 1970s, the county approved construction of the Seminole Bypass Canal to help control flooding along the Long Creek basin.

The canal helped the flooding problem but created what experts described as “hydrologic isolation.” Subsequently, officials decided to build an outfall pipe to provide flow into the lake to prevent stagnation and water quality problems.

However, the decreased flow of fresh water into the lake allowed for changes in water quality that contribute to the algae blooms.

As the county grew, the land surrounding Lake Seminole became more urbanized, creating additional problems for a water body that staff says was “predetermined by the physical origins of the lake and subsequent land use changes” to fail.

Over the years, the county has spent millions of dollars to keep Lake Seminole up to required standards. It is likely that the current restoration project will not be the last.

Lake Seminole is the county’s second largest freshwater lake. It is adjacent to Lake Seminole Park at 10015 Park Blvd. in Seminole. The park is a designated wildlife habitat and sanctuary. It has a 2-mile multi-use trail, picnic shelter, restrooms, playgrounds and more.

It also has a boat ramp to access the lake, which is used by boaters to fish or for water skiing.

Suzette Porter is TBN’s Pinellas County editor. She can be reached at [email protected].

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