With toxic algae blooms now erupting all over Florida — from the St. Johns River to Lake Okeechobee as well as on both coasts — scientists are pointing a finger at one likely fuel source: pollution from leaking septic tanks.

There are more than 2.6 million septic tanks in Florida, according to the state Department of Health. But less than 1 percent of them — about 17,000 — are being inspected to ensure they don't leak.

Scientists say that while leaks from septic tanks may not start toxic algae blooms, leaking septic tanks serve as fuel to keep the blooms going — like pouring gasoline on a fire.

In 2010, the Legislature passed a law requiring septic tank owners to get an inspection every five years to make sure they weren't polluting. But septic tank owners rebelled, and two years later legislators repealed the inspections.

The 2012 repeal, signed into law by Gov. Rick Scott, was spearheaded by former Sen. Charlie Dean, R-Inverness. Now, looking at all the algae blooms, he's not sure that was the right move.

"In my opinion, septic tanks are a major contributor," Dean said in an interview this week. "If we repealed the wrong thing, then yes, it's our fault."

Scott disagrees that repealing the inspection law was a mistake. "It's absurd to say that a bill that the Legislature passed with an overwhelming, bipartisan majority to save homeowners money six years ago has somehow caused the algal bloom problem that's been plaguing the state for decades," Scott spokesman McKinley Lewis said.

Instead, Lewis said, the governor blames the U.S. Army Corps of Engineers because that federal agency "has been releasing water from Lake Okeechobee into our communities for weeks." Scott has repeatedly urged the Corps to both repair and raise the dike around the lake, so the agency won't have to release so much of its algae-covered water to both coasts of the state during the rainy season.

Blue-green algae now covers 90 percent of Lake Okeechobee. As the Corps released excess water from the lake over the past month to avoid a breach in its aging dike, the algae has spread through the canals connecting the lake to the St. Lucie River on the east coast and the Caloosahatchee River near Fort Myers on the west coast.

But Florida's algae bloom headache is more widespread than just Lake Okeechobee and its connecting waterways.

A long-running Red Tide algae bloom on the state's west coast has been killing sea turtles, Goliath grouper and manatees in the Boca Grande area. Last week, a North Florida group that monitors the health of the St. Johns River, the St. Johns Riverkeeper, spotted more blue-green algae in the state's longest river, just south of Jacksonville and also in Brevard County.

"Septic tanks definitely play a role in the St. Johns algae equation," said Lisa Rinnaman, whose title is St. Johns Riverkeeper, noting that the dumping on farms of sewage sludge, known as "biosolids," also is a big factor, as is fertilizer in runoff.

The blue-green algae bloom that started in Lake Okeechobee earlier this summer is a repeat of one that caused an environmental and economic disaster on the state's east coast two years ago.

Afterward, a year-long study by scientist Brian Lapointe of the Harbor Branch Oceanographic Institute found that, while they may not start such blooms, leaking septic tanks feed them more nutrients to keep the bloom going and growing.

The primary sources of nutrient pollution that feed the algae blooms — in Lake Okeechobee and everywhere else — are fertilizer in the stormwater runoff from agricultural operations and suburban lawns and human waste from leaky septic tanks, Lapointe said this week.

All across the state, wherever you find the algae blooms you find "a lot of old (tanks) that were installed back in the '60s," he said. Experts say septic tanks more than 30 years old are more likely to malfunction and leak. About half the septic tanks in Florida are 30 or more years old.

But trying to get state officials to do something about the persistent pollution problem has proven nearly impossible, Lapointe said, because "it's a political hot potato."

One reason why: People who have septic tanks find it hard to believe they could be polluting because they can't see what's happening underground, he said.

Legislators found out how volatile the issue could be when they passed the inspection law in 2010. They took that step at the recommendation of a group of experts on the state's springs, originally assembled by former Gov. Jeb Bush. Many of the state's springs had begun suffering from algae blooms fueled by nutrient pollution.

To offset concerns about the cost, the 2010 law provided a grant program that would help low-income residents cover the inspections and any repairs that were needed.

But septic tank owners still objected to the cost of inspections, which ranged from $150 to $500 depending on the location, not to mention the cost of potentially replacing a tank that was leaking.

Home builders and business groups chimed in to oppose the measure, calling it a one-size-fits-all approach to a problem that varied from county to county. Tea Party groups took up the cause as well, claiming the inspection requirement constituted illegal discrimination against septic tank owners.

So the Legislature delayed implementing the law, and then, led by Dean, lawmakers repealed it before it ever had a chance to get started. It has not come back up since.

And even as algae blooms become a stinky, poisonous feature every summer, Lapointe said, "we're still permitting them." Census figures show about 900 people a day move to Florida, Lapointe said, "and 40 percent of them are going on septic tanks."

Times senior news researcher John Martin contributed to this report. Contact Craig Pittman at craig@tampabay.com. Follow @craigtimes.