An unquantified, but substantial amount of blue-green algae has bloomed at the Beaver Creek and South Fork Rivanna reservoirs, according to a new report presented to the Rivanna Water & Sewer Authority’s board of directors May 24. Consultants say the water supply at Ragged Mountain Reservoir is another one to watch.
Algae—caused by a nutrient overload—is problematic in a water system because it can cause taste and odor compounds, cyanotoxins and filter clogging.
At Beaver Creek and South Fork, consultants and RWSA staff have spent nearly $120,000 since 2014 on chemical treatments to stop the algae. While the consultants will present the board with a modified monitoring program for those reservoirs in the coming weeks, they have instructed staff to continue monitoring the water at Ragged Mountain, in which they have found occasional floating algae.
“I’d be very surprised if [Ragged Mountain Reservoir] didn’t develop problems very soon,” Alexander Horne, a professor emeritus of environmental engineering at the University of California, Berkeley, says. He, along with Kelly DiNatale of DiNatale Water Consultants, presented the report.
RWSA board members had questions about cost and procedures, but they all generally seemed to agree that treating the blue-green algae, or cyanobacteria, is a priority.
“It’s all going straight into your bathtub,” former city councilor Dede Smith said at the meeting. She has led the charge to keep Ragged Mountain Reservoir a natural area, while her opponents hope to make the area less exclusive by permitting dog walking, mountain biking and other recreational activities.
The side that leans toward permanently banning dogs and other pets often cites the harmful effects of animal droppings in the water supply.
“While livestock are the greatest contributor of animal waste, perhaps the least suspected source of animal waste is a man’s very own best friend,” the EPA states in a 2014 bulletin on its website. “Pets, particularly dogs, are significant contributors to source water contamination.”
The EPA has also cited dog waste as a contributor to excess nutrients that lead to algal bloom.
“It’s serious,” says Smith. “As a community, we have the opportunity now to prevent this from happening at what has become the single most important reservoir we have.”
But DiNatale points to research that shows Ragged Mountain may not need to remain sans Sparky for the overall health of the water supply.
“Animal droppings, whether from wild or domestic animals, represent a very minor source of nutrient inflows to the authority’s reservoirs,” he says. “We could remove all of the animals, both wild and domestic, but still would be experiencing algae blooms from all of the other sources.”
There’s always tension between allowing recreational activities near reservoirs and protecting the water supply, DiNatale says, and that’s partially why RWSA is looking for in-lake algae-management methods.
“With that said, it is always preferable to address whatever land use activities are manageable,” he says. “Every water provider would love to have a protected watershed without any animal or human impacts, but, as we know, that is impossible for virtually all of the country’s water supplies.”
But Smith cites a 2002 letter from the Virginia Department of Health to the authority, in which she says the department “admonished RWSA for not considering the quality of its raw water source.”
In the letter, the department stressed that the 1996 Safe Drinking Water Act Amendments and the EPA have placed “greater emphasis on source water protection and preventing contaminants from entering water supplies in lieu of the past practice of removing contaminants at water treatment facilities.”
According to Smith, failure to protect the water source has already led to contamination of half of our reservoirs, the necessity to add chemicals and heavy metals for purification and about $25 million in new infrastructure to deal with the worst of the pollution.
“In other words,” she says, “don’t contaminate your raw water source in the first place.”
Related Links:
May 10, 2016: Critics still question Ragged Mountain plan
March 9, 2016: One local wants litter removed from the Rivanna