Two scientists cast serious doubt Wednesday on claims that the Toledo-Lucas County Port Authority’s Facility 3 man-made island is leaching phosphorus into the Western Basin of Lake Erie.

The two scientific presentations, presented to a board committee, were aimed at responding to persistent claims that the deposit of bio-sludge from the city of Toledo on the island is leaching phosphorus that is fueling the algae blooms that shut down Toledo’s drinking water supply this year.

Jerry Chabler, the port board member who raised questions about the potential for contamination from Facility 3 and its effect on Toledo’s drinking water, said he found the two presentations persuasive.

“Everything I heard was overwhelming evidence that there wasn’t an issue out there,” Mr. Chabler said.

He said he would feel more confident if the analyses came from a “totally independent person” not hired by the sludge contractor or the U.S. Army Corps of Engineers, but said he trusted the competence and integrity of both presenters.

Toledo drinking water customers were advised on Aug. 2, 3, and 4 not to drink the city water because of an unsafe level of microcystin, a toxin produced by algae blooms in the lake near the water intake. Since then, scientists have generally blamed 40 percent of the problem on fertilizer and manure runoff in the Maumee River watershed and the rest on Detroit River and other tributaries.

For the last several years, S&L Fertilizer has used Facility 3, a 540-acre island at the mouth of the Maumee River, to make a topsoil product called Nu-Soil out of dredgings, sludge, and used lime.

Julie Hewlett, a senior geologist with the environmental consulting and soils engineering firm Bowser-Morner, said her firm was hired to conduct studies to help S&L comply with its environmental permit.

She said she did soil borings and described the permeability of the soil on Facility 3 as “extremely slow.” She said all the rain that lands on the island is channeled into ditches, then pumped into an area of vegetation where it is absorbed by roots or evaporates.

Ms. Hewlett’s photographs depicted an orderly operation in which sludge, dredged material, and used lime from the water treatment plant were combined into Nu-Soil.

She said the Facility 3 dikes hemming in the facility were built of 12 to 22 feet of impermeable soil. She said borings were drilled through 20 feet of compacted clay soil and were unable to drill into the bed of prepared limestone beneath the clay soil. Below that is sand.

“Our interpretation is there is nothing going from the surface through these underlying sand seams and out into the lake,” she said. “The only input of water is precipitation. The only exit is through evaporation.”

Asked by Mr. Chabler if Facility 3 contributes to the toxic algae in Lake Erie, Ms. Hew-lett said, “I don’t think so.”

Joseph DePinto, a water quality engineer with the Ann Arbor firm LimnoTech, studied the phosphorus released by open-lake dumping of dredged material for the Army Corps of Engineers, as required for the Corps’ permit.

Halting the release of dredged materials in the open lake would have no effect on algae growth, he said.

“The contribution from [Facility 3], compared to the total loading [of phosphorus in the Maumee River] can’t be large. It just can’t be,” Mr. DePinto said. He said his study cost about $200,000.

Contact Tom Henry at: thenry@theblade.com, 419-724-6079, or via Twitter @ecowriterohio.

First Published December 11, 2014, 5:00 a.m.