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Friday, Apr 20, 2018
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Tampa will tap Blue Sink to boost river flow

TAMPA — Tampa won approval this month for another project intended to protect the health of the Hillsborough River at times of drought.

The Southwest Florida Water Management District gave a green light last week to a plan to pump up to 2 million gallons of water a day from Blue Sink, a natural pool just west of the point where Fowler Avenue meets Florida Avenue.

The plan calls for running water lines from the sink to the foot of the city’s dam between Rowlett Park and Rogers Park in East Tampa. The dam, first built by ranchers a century ago, holds back the Hillsborough River to provide drinking water.

The modern dam was built in the 1940s. Most days, it allows enough fresh water past to push back against the slug of salt water that moves up from Tampa Bay on each high tide. The fresh and brackish water below the dam makes the river an important breeding ground for fish and other sea creatures.

That changes during droughts, when the freshwater flow slows to a trickle or stops entirely and salt water pushes farther up river.

Years of lawsuits and arguing over the health of the river helped produce a calculation known as the river’s minimum flow level. That’s nearly 11 million gallons a day from July to March and 13 million gallons a day from March to June.

Mayor Bob Buckhorn opened the first of four planned freshwater reserves last year when he flipped the switch on a new pump house at Sulphur Springs in North Tampa. That system can add nearly 10 million gallons of freshwater a day to the river during drought years.

If the river needs more help, the city plans to tap Blue Sink, the Tampa Bay Bypass Canal and, eventually, Morris Bridge Sink to the north — in that order.

“The intent is to make sure the health of the lower Hillsborough River is sustainable,” Buckhorn said this week.

The city and Swiftmud are splitting the cost of the $11 million Blue Sink project.

The idea of the city pumping millions of gallons of water from Blue Sink has the sink’s neighbors in the North Forest Hills area fearing for their wells. There are about 800 wells within a mile of the sink and Ewanowski Spring, which feeds it.

“We’re concerned about lake levels and possible sinkhole development,” North Forest Hills resident Jim Wilson told the Swiftmud board. “We’re just concerned about what might happen.”

Brad Baird, the city’s water department director, said the well owners have nothing to worry about. The city won’t pump from the sink year-round, Baird said. Some years, it may not need to draw from the sink at all.

“During wet years, we may not need to use Blue Sink at all,” Baird said this week. “One very dry year or a drought, we’ll probably need to use Blue Sink more than half the year.”

A 1996 study of Blue Sink and the surrounding land showed that pumping the sink at the level the city plans would drop lake levels by a foot or less.

Barbara Ewanowski, who owns the spring that feeds Blue Sink, welcomes the pumping.

The channel connecting the spring and the sink has been plugged by debris, causing the spring to back up and kill dozens of live oak trees on Ewanowski property, she said.

Pumping water from the sink will restore more of the natural flow from the spring and bring her property some relief, she told the Swiftmud board.

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