By Rod Nickel

(Reuters) - Testing of nine wells near a sinkhole at a Mosaic Co fertilizer facility in Florida, site of a massive leak of contaminated water, shows that water meets safe drinking standards for radioactivity and damage has not spread beyond the site, the company said.

A sinkhole 45 feet (13.7 meters) in diameter and 240 feet deep opened in late August at Mosaic's New Wales phosphate facility 30 miles east of Tampa. The retention pond of a phosphogypsum stack, a hill of hazardous waste generated by phosphate production, leaked the equivalent of 326 Olympic swimming pools of contaminated water into a Florida aquifer.

Samples were collected from wells within three to five miles of Mosaic's facility at Mulberry, Florida, by environmental consulting firm ECT. A third-party lab conducted tests measuring radioactivity in the water and found that they meet state and federal standards, Mosaic said in a statement on its website late on Wednesday.

"These results further verify that there have been no offsite impacts as a result of this incident," the Minnesota-based company said.

Others were not convinced.

Just because polluted water has not yet turned up off site, does not mean it will not happen in the future, said Bradley Marshall, a lawyer with Earthjustice, a nonprofit environmental law organization.

Louella Phillips, who has a well and lives about three miles east of the sinkhole, said her bathwater appeared rusty on one occasion after the Aug. 27 incident but before the public was notified in mid-September.

"We drank it for two to three weeks before they ever announced it," she told Tampa radio station WMNF on Tuesday. "All three kids have been sick ever since."

Mosaic said it has also completed a variety of other tests on 139 wells, with all showing normal results.

It said there are 690 more well tests scheduled.

A preliminary review of all available results by Florida's Department of Environmental Protection (DEP) shows they have met safe drinking water standards, said spokeswoman Dee Ann Miller. She confirmed that monitoring indicates the spilled water has not moved offsite.

Florida Governor Rick Scott said on Monday he was immediately requiring public notification of pollution incidents within 24 hours, following Mosaic's sinkhole and an unrelated sewage spill.

Mosaic has said it notified authorities as soon as it detected the leak on Aug. 27, however it did not warn residents until Sept. 15 after local media reported the sinkhole.

Mosaic shares rose 0.6 percent to $24.61 on Thursday, but have dropped some 11 percent since Aug. 26.

(Reporting by Rod Nickel in Winnipeg, Manitoba; Editing by Meredith Mazzilli)