Recapping the Carnelian Bay Sewage Spill
Safety protocols in reaction to the July 18 Carnelian Bay pipeline spill that leaked 85,000 gallons of raw sewage into Lake Tahoe are effectively over. Patton Landing and Carnelian West beaches have reopened, and Placer County has removed its health advisory, which extended a mile-and-a-half along the Carnelian Bay shoreline, straddling the spill site.
The investigation to understand what led to a Caltrans contractor striking the 24-inch main sewer export pipeline remains underway and involves multiple entities. Any penalties or potential litigation won’t be known until after everything is buttoned up.
“The North Tahoe Public Utility District is very pleased with how our team responded to the pipeline strike and sewer emergency on July 18,” wrote Justin Broglio, PUD public information officer, in an email to Moonshine Ink. “The NTPUD is grateful for the mutual aid we received from our neighboring agencies (Tahoe City PUD, Truckee Sanitary District, Olympic Valley Public Service District, Incline Village General Improvement District, South Tahoe PUD, and Placer County) and from Q&D Construction (who happened to be working for Southwest Gas nearby). With their help, we were able to respond and complete the repair, cleanup, and disinfection much more rapidly.” He also credited the public for its understanding during closures, the water quality team for collecting samples, and the communications teams for keeping people updated.
As of press deadline, here’s what we know about the incident.
On the evening of Thursday, July 18, a Caltrans private contractor was 4 days into a 3-week job of installing a pedestrian crosswalk and Rectangular Rapid Flash Beacon at the intersection of Center Street and state Route 28 in Carnelian Bay.
The contractor had issued a USA locate request, which the North Tahoe Public Utility District responded to by marking its underground utilities in advance of any excavation.
At about 8 p.m. that Thursday night, the contractor struck NTPUD’s main sewer export line about 200 feet from Lake Tahoe’s edge. The line, installed in the 1960s, does not utilize modern safeguards for locating utilities, such as underground tape or tracer wire. However, the PUD has locating equipment to identify underground utilities.
Per the Porter-Cologne Water Quality Control Act, wastewater in the Tahoe Basin must be collected and pumped out. The main sewer export pipeline that was hit is continually pressurized at 40 to 50 pounds per square inch (psi; similar to the pressure felt at 92 to 115 feet underwater), so any sewage can be moved uphill toward the Dollar Hill pump station, where it enters the Tahoe City sewer system and flows via gravity to the Tahoe-Truckee Sanitation Agency treatment plant in Truckee. Because of the pipeline’s pressurization, the spill was exacerbated, but so was the response.
“NTPUD on-call utility crews received the emergency call … and were on-scene within minutes,” Broglio said. “The district was able to bypass the leak area [using 12 Vac-Con, or vacuum trucks] and allow crews access to the break. The pipe was repaired at approximately 3 a.m. We estimate that the pipe leaked for approximately 45 minutes to an hour.”
During that time, an estimated 125,000 gallons of untreated sewage spilled out from the break site. About 40,000 gallons were collected and returned to the export system. The remaining 85,000 gallons flowed through the adjacent parking lot and into Tahoe.
With the pipe repaired, crews turned their attention to disinfecting the impacted surfaces between the sewer line and the lake. Through the night and into the next day, July 19, PUD crews washed the parking lot with water and applied “a sodium hypochlorite solution (commonly known as bleach) to all hard surfaces and impacted areas above the lake,” Broglio said. “In collaboration with the California Tahoe Conservancy and Placer County, the NTPUD has completed the initial site restoration and removal of all impacted landscaping and rockwork surrounding the spill area.”
In this case, the infrastructure was in okay condition, so it was literally an accident. This wasn’t an issue of aging infrastructure and dilapidated equipment that wasn’t being taken care of.”
~ Jeff Cowen, Tahoe Regional Planning Agency
Patton Landing and Carnelian West beaches were closed, and a health advisory issued in the area of the spill. Residents and visitors alike were warned that any contact with the lake water off the spill site could result in illness.
Anik Wild, co-owner of Tahoe Watermans Landing, was contacted early Friday morning by the PUD and told the beach was closed and no watercraft rentals would be allowed for the business at least through the weekend, which sat within the health advisory zone.
Ultimately, the rental side would be closed for 7 days. Wild had to cancel a kids camp and numerous reservations. “The café remained open, but it was so slow because I think people were avoiding the area altogether,” Wild said. “What was really discouraging was not everyone was clear that the [drinking water] was not taken from the lake and our coffee was clean.”
By 4 p.m. on July 19, the disinfection and remediation of the impacted area was complete. It turned into a waiting game of taking water samples from the lake and testing for elevated levels of bacteria. Processing time for samples was at least 24 hours, and not until there were 2 consecutive days’ worth of normal bacteria levels would the closures be removed.
So how does the water bounce back from 85,000 gallons of raw sewage? According to the PUD, “there are no commonly known practical methods to treat a large volume of lake water, especially in a water body as large as Lake Tahoe.” Addressing the fecal coliform and Escherichia coli (E. coli) found in Tahoe samples after the spill simply takes times.
“With the size and the dilution of Lake Tahoe, there needs to be sustained pollutant load entering the lake for it to really register,” explained Jeff Cowen with the Tahoe Regional Planning Agency.
“The elevated levels of bacteria, as a result of the sewer spill, begin to die off in the environment rapidly due to lack of nutrients and exposure to ultraviolet light from the sun,” Broglio explained. He added that some of the concerning bacteria present in untreated sewage already naturally occurs in the lake, just at lower concentrations.
Patton Landing Beach was the first to pass the test: 1 week after the spill, water quality tests showed bacteria levels returned to a normal range and were within California beach water quality standards. The beach reopened.
On July 31, the health advisory was lifted completely, and Carnelian West Beach reopened. “Residents and visitors may resume water contact and recreation activities at this location,” noted the final incident update issued by the PUD.
Construction crews have worked to restore any removed landscaping impacted by the spill with an anticipated completion date of Aug. 6. What remains at this point is completing the investigation.
The Lahontan Regional Water Quality Control Board serves as point for the investigation into what happened and will be the entity proposing any penalties.
“For the Carnelian Bay spill, the Lahontan water board has performed an inspection and begun working with North Tahoe Public Utility District to investigate the cause of the sewage spill into Lake Tahoe,” shared Nick Cahill, public information officer for the California water control board. “Formal enforcement is confidential until the public comment phase and resolutions are case-by-case specific. At this time, there is no timeline or estimate on potential penalties. Once scheduled, a notice regarding the public comment period for this incident will be posted on our enforcement website, waterboards.ca.gov/lahontan/water_issues/programs/enforcement.”
In 2005, after a similar raw sewage spill in Kings Beach, Lahontan issued a $325,000 penalty for the property owners and contractor involved. In 2012, Lahontan issued a $239,081.25 penalty on NTPUD after the December 2010 discharge of raw sewage from a Dollar Hill pump station into Tahoe.
The state water board maintains a Sanitary Sewer Spills incident map, which shows three sewer incidents (not including the July spill) in Moonshine’s coverage area that have reached Lake Tahoe’s waters. View the map, which as of press deadline was last updated in January 2024, at waterboards.ca.gov/water_issues/programs/sso/sso_map/sso_pub.html.
The TRPA is conducting its own investigation on the recent incident as well. “Through our investigation, the objective is to find out what happened, find out if there were safeguards in place that worked or that didn’t work, and then to take steps to make sure that it doesn’t happen again,” Cowen said. “In this case, the infrastructure was in okay condition, so it was literally an accident. This wasn’t an issue of aging infrastructure and dilapidated equipment that wasn’t being taken care of. Those would be instances in which TRPA would have a little bit bigger role ’cause we’re a permitting agency around projects and buildings and things like that. So, we would be a little bit more involved at that point.”
It could be months before the Lahontan investigation is completed. In the meantime, businesses like Watermans Landing have all but returned to business as usual.
“There are little things that I didn’t think through,” Wild said. “The reputation of the area for the remainder of the summer, now I’m realizing some people will avoid the area.” She spoke of regular customers who’ve stayed away even with bacteria levels having returned to normal over lingering fears of E. coli poisoning. Other residents, though, have made a point to buy gift cards to keep the business from struggling over the week-long loss of business. “We’re grateful that we’re up and running and get to swim and put people in the water and do what we do best in the summer months,” she said.
She added that she’s also grateful for the NTPUD and other agencies for responding to the leak so quickly: “They’re the heroes.”
