TAHOE CITY, Calif. - Regional officials are attempting to identify the amount of sewage that seeped from a Dollar Hill manhole and eventually dripped into Lake Tahoe after a severe pre-Christmas snow storm compromised a local utility district's network of power generators.
The storm created a power outage on the northwestern shore of Lake Tahoe, in turn spurring a sewage spill in the North Tahoe Public Utility District that led to "a significant amount of sewage" reaching the waters of the lake, an official confirmed this week.
The spill occurred when the Dec. 19 power outage compromised NTPUD's main generator, said Paul Schultz, acting general manager of NTPUD. A backup generator - installed at the Dollar Hill Main Sewer Pump Station in Tahoe City this summer - also failed, causing a backup in the piping system, which led sewage to seep out of a manhole located on Highway 28 near the base of Dollar Hill.
Schultz said the district estimates 61,000 gallons of raw sewage escaped the manhole, and "a small portion reached the lake."
However, Scott Ferguson, senior water resource control engineer for the Lahontan Regional Water Quality Control Board, said he had heard the total discharge amount was closer to 150,000 gallons, with a "significant" amount reaching Lake Tahoe.
"The spill was in proximity to the lake and the steep terrain made it a short trip," Ferguson said.
Lane Lewis, NTPUD board president, said the discrepancy stemmed from the reporting of the spill, in that NTPUD was required to give an initial estimate to Lahontan and has since consulted data which provides a more accurate figure.
"(The district) was allotted a period of time to establish a more precise figure," he said. "We will have a better understanding of the exact specifics once the investigation is complete and a report is finalized."
An immediate consequence of the spill includes the possibility of bacterial contamination that could impact drinking water quality for residents, Ferguson said.
Schultz said NTPUD tested Lake Tahoe's waters near the spill site on Dec. 20, 21 and 22 for fecal coliform, turbidity and chlorine residual - samples came back clean, he said.
Furthermore, Lane said a full cleanup of the site was performed using vactor trucks - vehicles equipped with high-power vacuums.
However, Ferguson warned that long-term effects from the spill could occur.
"Wastewater contains nutrients such as nitrogen and phosphorus that provides food for algae," Ferguson said. "There could be localized effects on algal growth once things warm up."
Tahoe scientists have often said algal growth in the nearshore environment is a contributing factor to Lake Tahoe's trend of clarity decline.
Schultz confirmed one homeowner's residence in proximity to the spill was inundated with sewage. He did not release the name of the homeowner.
NTPUD's infrastructure did not sustain damage, nor did the generator, Lewis said.
While Schultz said the accident was unfortunate, he said it could have been worse and praised NTPUD employees who responded to the emergency.
"Our crews utilized a series of holding tanks to hold as much sewage as possible," he said. "The crews did a very good job, and their judicious response kept the situation from evolving into multiple spills."
NTPUD will submit a full report to Lahontan and the Placer County Environmen-tal Health Agency within 30 days, Schultz said.
Ferguson said Lahontan will be "looking at the report closely."
"This is one of (Lahontan's) enforcement priorities," he said.
Ferguson said NTPUD could be subject to a compliance schedule, wherein Lahontan would mandate system upgrades within a certain time frame to prevent a repeat occurrence.
Additionally, the utility district could be subject to fines of $10,000, with an additional $10 per gallon in excess of 1,000 gallons, Ferguson said.
NTPUD, founded in 1948, provides sewer services to about 5,500 residents in Kings Beach, Tahoe Vista, Brockway Vista, Carnelian Bay, Cedar Flat and Agate Bay, between the Nevada/California state line and Dollar Hill.