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Alafia Siphoning Boost On The Table

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By SUSAN M. GREEN, The Tampa Tribune

Published: October 20, 2007

Updated: 10/18/2007 11:34 pm

RIVERVIEW - Long tapped for recreation, industry and irrigation needs, the Alafia River also has become a major source of drinking water for the growing Tampa Bay region.

But how much of its flow can be harvested for human needs before aquatic animals, birds and other creatures that live near the river or the estuary it feeds feel the pinch?

Scientists at the Southwest Florida Water Management District, the state agency charged with setting minimum flow standards for rivers in the region, think they have the answer.

A recommendation that no more than 19 percent of the river's flow be siphoned off, and then only when the Alafia is running at 77.5 million gallons a day or more, was presented recently to the Alafia River Basin Board and committees of the Tampa Bay Estuary Program and Agency on Bay Management.

'Nineteen percent sounds like a lot of water,' district senior scientist Sid Flannery told ABM members last week. 'When you make people scale the amount of water withdrawn to the rate of flow, it's an incredibly protective measure.'

The proposal also is being 'peer-reviewed,' or formally evaluated by a panel of experts from Texas, Georgia and Mississippi, said Flannery, who oversaw the district's study to determine the recommended flow level.

The recommendation is expected to go to the water management district's governing board for a decision late this year or in early 2008, and public hearings will be announced, Flannery said. If adopted, the standard would apply to the lower Alafia, defined as the stretch from Bell Shoals Road downstream to the mouth of the river.

'We feel like we've collected extensive data' to support the proposed standard, Flannery said.

He said studies show no significant environmental harm would come to the river with the proposed standard, though saltwater may push slightly farther upstream. The district is predicting a decline of up to 15 percent of two species considered important to the food chain - mysid shrimp and juvenile red drum - but that's not expected to create lasting harm, Flannery said.

Boaters, fishermen and people who live along the river should see no changes to the river if the standard is adopted, Flannery said.

He added that comparisons of rainfall records from the 1950s and '60s with the 1970s and later years show some observations of reduced river flow, long chalked up to human meddling, actually stem from climate changes.

It's difficult to say how the proposed standard compares to current withdrawals, Flannery said. Tampa Bay Water, the supplier of much of the region's drinking water, holds a permit to withdraw up to 10 percent of the Alafia's flow when at least 80 million gallons a day, or 124 cubic feet per second, is pouring past gauges positioned along the river around Bell Shoals Road.

That threshold precludes withdrawals about 18 percent of the year, Flannery said.

The proposal would change the threshold for withdrawals to 120 cubic feet per second, or 77.5 million gallons a day, thus allowing withdrawals more often than now, Flannery said. It also would add flows from Buckhorn Springs, currently not counted in the river flow for permit purposes, into the mix used for calculating the Alafia's overall volume.

Mosaic Fertilizer, which mines and processes phosphate along the river, holds a permit that allows an average withdrawal of up to 6 million gallons a day, but the company is not bound by any threshold for ceasing its diversions.

Flannery said any new standards governing the river's minimum flows will apply to Mosaic and any future permitted withdrawals.

Currently, it's 'very rare' that the diversions of Tampa Bay Water and Mosaic tally 19 percent of the river's flow, Flannery said. Because the river flow varies widely, he said he couldn't easily calculate how Mosaic's usage would fit in with the new standard or how much the withdrawal amounts would change.

'The water use permits are currently less than 19 percent,' Flannery said.

Some community leaders said they had spoken to Flannery after hearing about the proposal and in the wake of recent emergency orders allowing Tampa Bay Water to exceed its permitted withdrawals for three months to stockpile water for the dry spring months.

Peter White, president of the Alafia River Ridge Civic Association, said he worries that the standard is being driven by population growth. He said the association will discuss the proposed Alafia minimum flow recommendations at a meeting at 7 p.m. Nov. 6 at the Riverview Civic Center, 11020 Park Drive.

'They water users can draw down 19 percent of the river, and what happens when they get more and more people?' he said.

Reporter Susan M. Green can be reached at (813) 865-1566 or sgreen@tampatrib.com.

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