Pinecrest Reservoir

A photo of Pinecrest Reservoir on March 28 shows the rising water had submerged the boat launch.

Despite not facing the threat of a water shortage this year, Tuolumne Utilities District will begin doing public outreach next month to encourage voluntary conservation as required by Gov. Gavin Newsom’s recent executive order related to the ongoing California drought.

The TUD Board of Directors got a water-supply update from Associate District Engineer Glen Nunnelley on Tuesday at a public meeting where the water and sewer agency’s requirements under Newsom’s statewide measures were also discussed.

Nunnelley explained how storms late last year that brought historic amounts of rain and snow to the area ensured that Pinecrest and Lyons reservoirs, which TUD relies on for more than 90% of the water it provides to more than 40,000 county residents, will fill with water this year.

However, there’s a likelihood that the “end of spill” — the point after the snowmelt has flowed into the reservoirs and TUD must rely on storage for the remainder of the year — will happen earlier than normal, as it did last year, and put additional pressure on the overall system.

“There’s not necessarily a water shortage, because the reservoirs will fill, but we do have a stressed system because of the drought here in Tuolumne County,” Nunnelley said, “so the district will be rolling out public outreach to use water beneficially this year.”

Newsom’s March 28 drought order requires water providers like TUD to move into the so-called “level II” phase of their contingency plans for water shortages, which for TUD is mostly focused on outdoor water usage and could include:

• expanding its public information campaign to encourage voluntary reductions in water use;

• getting customers to repair leaks, break and malfunctions in a timely manner;

• sending out notices to high water users;

• restricting or prohibiting water runoff from landscape irrigation;

• limiting landscape irrigation to specific times; and

• reducing water loss within the district’s conveyance system.

Nunnelley’s presentation to the board showed the snowpack in the South Fork Stanislaus River watershed that feeds Pinecrest and Lyons reservoirs, which are owned and operated by Pacific Gas and Electric Co., was about 33% of average as of Tuesday.

The water runoff in the South Fork of the Stanislaus River was expected to be 60% of average this year, Nunnelley said, noting that all numbers were subject to change based on potential for some more rain and snow in the coming days.

Nunnelley said early storms brought 15 inches of rain to Sonora from October through December, when the historical average is normally 10 inches. From January through March, however, Sonora received only 1.6 inches of rain when it would normally get 17 inches over that period.

“So that’s the big impact that’s occurring,” Nunnelley said, referring to the wet start of the year followed by the historically dry past three months. “We learned early on that we would fill the reservoirs, which is a good thing.”

Pinecrest Reservoir was holding about 13,073 acre-feet of water as of April 5, or 71% of capacity and 146% of the historical average date. Lyons Reservoir was holding about 3,911 acre-feet, or 71% of its capacity and 99% of the historical average to date.

The district’s system isn’t as prone to the impacts of multiple dry years because the water supply resets each year as snow melts fills them up in spring, which gets TUD through the summer, then are drawn down after Labor Day as PG&E diverts more water for hydropower.

Nunnelley noted that the way the system works means that one “very, very dry year” can impact TUD more than others. That was the case in the spring of 2014 when there was concern that the reservoirs wouldn’t fill all the way, which resulted in the district calling for customers to cut back as much as 50% while much of the rest of the state was required to reduce by less.

“We ended the calendar year with pretty much no precipitation (in 2013-14), and reservoir levels were relatively low, so we couldn’t say with certainty whether we would fill them.” 

In addition, the district was required back in 2013-14 to maintain Pinecrest Reservoir’s lake level above a certain height from the end of spill until Labor Day to preserve its recreational benefits, but TUD and PG&E have since brokered an amendment with state water regulators that would allow the level to be drawn down lower in dry years.

As part of the upcoming conservation campaign, TUD will bring back a program from the previous drought that offers rebates for customers to replace older toilets with newer, more efficient models.

Nunnelley said less efficient toilets use about 3 to 4 gallons per flush, while the modern standards for efficiency are 1 to 1.6 gallons per flush.

“That’ll help conserve some water,” he said.

The state is calling for residents to voluntarily cut water consumption by 15% compared with what they used in 2020, though Nunnelley noted how TUD customers have already reduced their usage considerably over the years. 

Nunnelley pulled up data that showedthe amount of use by TUD water customers is about 14% below the state average for 2020 and last year at 133 gallons per capita per day, compared with 155 gallons per capita per day statewide.

Barbara Balen, the TUD board president, noted how many of the state’s recent measures were tailored toward coastal cities where treated water used for landscaping and watering lawns ultimately flows into the ocean.

“Ours creates habitat and food and industry for ranches and what not,” she said. “It’s very different as we get into the politics, if you will, and drought can be regulated also… it may not actually be a drought somewhere, but the state has determined it’s a drought.”

There was some concern raised by TUD board member David Boatright, the district’s former wastewater superintendent before retiring and running for office in 2020, about too much conservation leading to not enough water in the wastewater system to push “solids” through the sewer pipes.

Don Perkins, general manager of TUD, acknowledged that lack of enough flow in the wastewater system can be a concern, but that there’s no evidence water conservation has resulted in an increase of sewer problems.

“We don’t want to discourage sanitary use of water,” Perkins said. “For one, it’s sanitary, we need to be clean. We live in a civilized society and need to clean ourselves and keep things clean. Two, recognize that 100% of our sewer water that gets treated isn’t wasted and gets put to beneficial use in the ag lands down below.”

Contact Alex MacLean at amaclean@uniondemocrat.com or (209) 588-4541.