RIVERVIEW — It's been a difficult couple of years for the Alafia River.
A 2007 ammonia leak killed fish and caused algae blooms. Rampant development brought waves of untreated water. The prolonged drought has slowed its flow to a trickle — 20 percent of its historical monthly average, and officials want to siphon off even more water. Phosphorus produced by nature and industry courses through the river.
While the Alafia — Riverview's best-known natural landmark — seems to be enduring its recent woes, experts and officials say things are stable but far from ideal.
The confluence of problems poses a threat to wildlife that depend on the river, said Peter Clark, director of Tampa Bay Watch.
Clark ticks off the trickle-down effects of drought, development and phosphate: Too much algae and too little water threatens sea grass beds at the river's mouth. That means mullet, shrimp and other marine life have a harder time finding food and shelter, in turn affecting birds that feed on sea creatures.
Clean-water rules that cracked down on industrial discharges began paying dividends for the Alafia in the 1980s, said Richard Boler, a water quality specialist with the Hillsborough County Environmental Protection Commission.
"I've been doing water-quality work for over 30 years and it's always been bad, [though] not as bad as it used to be," he said.
Phosphorus levels, which haven't changed much in 10 years, remain a problem, he said.
The Alafia, Boler said, has naturally high phosphorus levels because it's present in riverbed rock. Industry along the river also contributes to the phosphorus load, he added.
While industry has made strides in environmental protection over the years and isn't breaking any rules, Boler considers the river's water quality to be poor.
Officials from the Mosaic Co., which runs several mines and a fertilizer-processing plant in the Alafia watershed, say algae blooms are rare in rivers. The company's operations, they note, comply with all environmental regulations.
"Are there nutrients in our discharges? Yes," said David Townsend, Mosaic assistant vice president of public affairs. "But we are committed to always meeting our permits."
Many Florida waterways, not just those near Mosaic's operations, have an abundance of algae-producing nutrients, said David Jellerson, Mosaic's assistant vice president for environmental issues.
Mosaic spent $30 million to boost water-storage capacity at a Riverview fertilizer plant after Hurricane Frances. During the 2004 storm, a breached dike at the plant — then owned by Cargill — allowed some 60,000 gallons of contaminated wastewater to pour into Archie Creek, which flows into the Tampa Bay. The changes, Mosaic officials said, are meant to prevent the accidental overflow of acidic gypsum stack water.
Both environmental and phosphate-industry officials agree that scattered sources — such as greasy runoff from cars and untreated stormwater — also put the river at risk.
It's much easier to identify and fix a problematic pipe or pond, however, than to hunt down the myriad decentralized sources of water pollution, Boler said.
"That's a much more difficult task," he said.
Long-term population growth also weighs on the river by bringing more grimy runoff, Clark said. Meanwhile, Tampa Bay Water is looking to draw more water from the Alafia, said Paula Dye, chief environmental planner for the regional water provider.
Four years of below-average rainfall, Dye said, have made it nearly impossible in recent months to withdraw the permitted 52 million gallons a day from the Alafia.
Still, water managers are investigating whether more water could be taken from the Alafia without harming it. Proposals for future development of water resources, Dye said, include increased use of the river's water.
At stake is the delicate ecological balance between the river and Tampa Bay. Estuaries are so ecologically and commercially valuable, Clark said, because they're the habitat where many juvenile species of fish can find food and shelter.
That, Clark said, makes the Alafia's freshwater invaluable to marine life.
"You lose the fish that depend on the freshwater inflow," he said.
Some riverside businesses and residents worry that low water levels and more development will ruin the river.
The drought and dry-season declines in water levels have scratched many canoe trips on the upper end of the river, said Sybil Cribbs, owner of Alafia River Canoe Rentals in Valrico. Her business now only operates on weekends because of low-water conditions.
"Customers call to ask about river conditions and say, 'I think I'll wait till it rains,' " she said.
Rich Hollis, co-owner of Dixie's Dockside in Gibsonton, said there are days when he can't take his boat out because the water is so low. Another decline, he said, spells trouble for his business because some customers won't be able to arrive by boat.
"Our customers want to be able to get in and out," he said.
At the Beer Shed, a waterfront bar in Riverview, Fred Schmid, 68, nurses a Budweiser. The retired commercial fisherman says that the river seems cleaner than when he moved here in 1988, but he has reservations about the future.
"Too much development," he said, "That's what causes all the pollution — human beings."
Times Staff Writer Victoria Bekiempis can be reached at (813) 661-2442 or firstname.lastname@example.org.