ST. PETERSBURG — First it was red, then green and black, then red and green again. For more than a month, something unusually colorful has been flowing into the Northeast wastewater plant.Workers at an off-site pump station first noticed the "unknown substance" flowing through the pipes in late January, according to a complaint written by the plant operator. He bemoaned that the problem went unaddressed for weeks before samples were collected for testing.It’s March, and city officials still don’t know what it is. It appears to be a dye flowing into the sewage system, they said. It does not appear to be toxic. But other mysteries remain."We still don’t know yet where it’s coming from," Public Works Administrator Claude Tankerskley said. "But it’s most likely from a printing shop."The mysterious colors were revealed in a memo written by plant operator Craven Askew to Mayor Rick Kriseman and every member of the City Council.TAMPA BAY TIMES COVERAGE: ST. PETE’S SEWAGE CRISIS Latest sewage crisis fallout: Higher utility bills in St. Pete (July 27, 2017) No criminal charges in St. Pete’s 1 billion gallon sewage crisis (Oct. 27, 2017) Utility bills will rise for St. Pete residents — and keep rising (Nov. 9, 2017) Game of Rates: Will St. Pete raise reclaimed water bills? (Dec. 4, 2017)<St. Petersburg has a history of sewage issues, and Askew played a prominent role in publicizing some of those issues. In 2016 he emailed the mayor claiming city officials should have known that closing the Albert Whitted treatment plant would overwhelm the city’s three remaining plants. A 2014 study that Askew claimed the city buried said as much, and he wanted federal whistleblower protection for coming forward.The City Council voted to close Albert Whitted in 2011 and the Kriseman administration carried out the plan in 2015. The rest is history: the city’s overwhelmed sewage system released up to 1 billion gallons of waste from 2015-16 — 200 million gallons of which ended up in Tampa Bay.It’s costing the city $326 million to fix its sewage system. Now Askew has sent out another memo, and is once again asking for whistleblower protection.• • •Askew wrote in the March 5 complaint that, despite knowing about the discoloration for weeks, city officials collected the first samples on March 2.Tankersley, though, said there were no indication of a serious problem: The color would come and go periodically and did not smell. Dangerous pollutants often give off a distinct odor."If (city workers) had noticed an odor, they would have been more concerned," Tankersely said. "Just because you can’t identity what’s in the water, doesn’t mean it’s bad."So what is the source of all this? The city doesn’t know yet.There’s no prohibition against a company dumping industrial chemicals down the drain, he said — even dangerous ones. But the city requires some companies to pretreat their wastewater before it enters the city system to mitigate the danger of certain chemicals.City officials believe the source is a print shop — they don’t know which — flushing its dyes down the drain. There isn’t a print shop in the area that’s part of the city’s industrial pretreatment program. A company dumping dyes doesn’t have to be in the city’s pretreatment program, Tankersley said, unless the dyes proved to be toxic.Askew also complained that he was kept in the dark for weeks about the substance flowing into his plant by higher-ups at the city’s public works department. He said emails show city workers noticed the problem on Jan. 25, but Askew said he wasn’t told until late February.The Northeast plant had been having water quality issues since November, Askew said, and knowing about the mystery substance at the time could have helped him address the issue faster.But Tankersley disputed that Askew didn’t know about the colors. The administrator said Askew’s colleagues and supervisors told Takersley they had verbally told Askew about the discoloration. Tankersley said there are no emails to confirm that.• • •Askew also complained that the city changed his report to the state about a Jan. 18 spill in which 266,666 gallons of treated reclaimed water leaked from the plant.He said he wrote in the first draft of the city’s report that about 100,000 gallons of reclaimed water entered a ditch that led to Tampa Bay. When city officials submitted the final report to the state later that day, Tankersley said, officials removed the reference to the bay because they were sure the reclaimed water didn’t reach Tampa Bay.However, two days after the spill, public works spokesman Bill Logan texted a Tampa Bay Times reporter to say that "there is no way to know how much of that fully-treated reclaimed-quality water — if any — went into the waters leading into the bay.""That’s the final word," Logan added then.When asked about this discrepancy, he said the city investigated the spill further and believed there was "no way" it could have reached the bay."Indeed, at first, there was no way to know, so we initiated a more thorough inquiry," Logan said via email.But Logan also confirmed that the city changed Askew’s report before it had completed its inquiry: "Proper investigation was conducted ... It was then that we could fully confirm that the statement excised from the reporting to FDEP and the public was — in fact —inaccurate."Askew cited city procedures that say he has the right to final review of any reports submitted to DEP pertaining to the plant he oversees. But Tankersley pointed to conflicting procedures and state law that show the city, not plant operator, has final approval over reports."I have no dispute with Mr. Askew over the fact that he wanted to have the final say," Tankersely said. "What I dispute with him is that he had a right to." He acknowledged the city’s procedures contradicted each other.Both DEP and the Florida Fish and Wildlife Conservation Commission, which investigated the previous sewage issues, are aware of Askew’s complaints. DEP said it is investigating whether the city violated any state laws. FWC said it is considering whether to get involved.Askew wrote the complaint in order to seek federal whistleblower protection. He believes withholding information from him was a way for his superiors to discredit him for failing to address the issues at the Northeast plant. He fears he’s being targeted for alerting the public to the sewage issues in 2016."I will take this as a retaliation and undermining my abilities to perform my duties due to lack of critical information," he wrote.Tankersley denied that was the case."I find that sad," he said. "Because it’s not true. And I’m sorry he has so much fear."Staff writer Charlie Frago contributed to this report. Contact Josh Solomon at (813) 909-4613 or [email protected] Follow @ByJoshSolomon.