Warnings to keep out of three Columbia area rivers contaminated by sewer spills will continue through the weekend as state environmental officials again checked water quality Friday.
Meanwhile, high waters have closed parts of riverfront parks.
The new tests came after two previous rounds found significant variation in the amount of fecal coliform in the Broad, Congaree and lower Saluda rivers.
One set of tests taken at the Alpine Utilities plant on the lower Saluda initially measured bacterial pollution at 40 times the maximum safe level and then fell to nearly nothing Thursday, officials said.
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Such yo-yo measurements make it impossible to know whether the contamination is washing away amid high water caused by storms Wednesday or if more is yet to be discovered, officials said.
"It's all over the place," said Adam Myrick, a spokesman for the state Department of Health and Environmental Control. "We're need more (tests) to show us a good picture."
Riverkeeper Alan Mehrzad wants officials to come up with a plan for avoiding such spills.
"This is an opportunity to learn more on why it happened and to prevent it in the future," he said.
Officials say the storm tripled the normal levels of wastewater coming into treatment plants, overwhelming them.
The spurt created line breaks and other equipment failures, DHEC officials said.
Public and private sewer plant operators increased treatment efforts to reduce contamination, but heavy flows forced the release of much wastewater with less treatment than usual at some facilities, officials said.
Signs warning boaters and waders to stay off the rivers went up Wednesday.
The alerts went up at eight landings after officials decided the spills would push fecal coliform contamination in the rivers above the maximum daily safety level of 400 colonies per 100 milliliters of water.
Tests DHEC officials took of wastewater released at three plants showed wide differences in those counts:
- Columbia: 17 Wednesday and 5,000 Thursday.
- Alpine Utilities: 16,000 Wednesday and 2 Thursday.
- Bush River Utilities: 4 Wednesday and 2 Thursday.
Those snapshots of tainted water are inconclusive, Myrick said.
"We're all over the map."
Flooding along the rivers created by storm runoff is as much a concern for some as the contamination from sewage.
Granby Park in Columbia is closed indefinitely because of flooding on the Congaree from storm runoff.
Parts of the park - located at 100 Catawba St. in the Olympia neighborhood - are inundated by as much as 4 feet of water, city officials said.
Portions of the Riverwalk on the Congaree in Cayce and West Columbia are flooded, officials said.
A viewing pier on the path in Cayce was destroyed when a tree fell on it and it can't be repaired until the river recedes, city manager John Sharpe said.
Float trip operators also canceled trips this weekend because of what they said are rivers too risky to go on even if the water wasn't tainted.
"It's so incredibly dangerous because it's so high," said Katie Ghelardini of Adventure Carolina in Cayce.