The Catawba Riverkeeper Foundation says Tega Cay Water Service is harming the water supply for some people in the Lake Wylie area.
About 800 homes along the lake have their sewage treated by Tega Cay Water Service. The private company treats raw sewage and then discharges it directly into the water.
"It's very bad and it has been an ongoing problem for more than two years now," Catawba River keeper David Merryman said.
Merryman is fighting a recent decision by the South Carolina Department of Health and Environmental Control (DHEC) to give Tega Cay Water Service a new five-year permit to operate. Merryman said the company should be required to make serious upgrades before it receives the permit.
"They have been loading Lake Wylie with phosphorous, which contributes to algae blooms, which our volunteers have documented the past four seasons," he said.
Merryman said algae blooms can suck oxygen out of the water, sometimes killing fish; expose swimmers to infection; and cause taste and odor problems for cities like Tega Cay, Rock Hill and Fort Mill.
PHOTOS: Merryman: Algae Blooms Documented On Lake Wylie
Another reason Merryman said he is appealing the utility's permit is frequent sanitary sewer overflows, such as one documented by Whistleblower 9 in February.
A consent order that DHEC sent to Tega Cay Water Service on Oct. 1 fines the company $22,000 for sewer overflows and orders it to come up with a plan to make upgrades.
PDF: DHEC Consent Order
But Merryman said that's just a slap on the wrist and lobbied DHEC for a special hearing, which is set for Wednesday. He will go before the board and argue that the permit should be changed or revoked.
If that doesn't happen, Merryman said things will get worse.
"I think we will see more days where it isn't safe to recreate in Lake Wylie without people having to be utterly concerned about infections, or water that could lead to other skin or health problems," he said.
Patrick Flynn, the regional director for Tega Cay Water Service, said he had no comment but that the company will make its case in front of the DHEC board on Wednesday.