SOUTH LAKE TAHOE, Calif. – The South Tahoe Public Utilities Department (STPUD) held a stakeholders advisory group and public information meeting regarding how they deal with recycled water. The plan is open for comment from October 24 to November 11.

STPUD was established in 1950 to provide drinking water and provide sewage collection, treatment, and export for the South Tahoe community. Since California has limited water supplies, the entire state has recycled wastewater for decades through chemical and microbiological treatment. STPUD is no different and currently recycles 100% of its wastewater.

Because of the Porter Cologne Act, which protects water quality and water use in the state, the STPUD began exporting its wastewater to facilities in Alpine County in 1967, a response to environmentally protect the watershed of Lake Tahoe. Since then, STPUD has worked with Alpine County and Harvey Place Reservoir to store and distribute wastewater—a costly endeavor, as the water must be pumped over 26 miles over major elevation changes.

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Though recycled wastewater can be treated and made potable, or safely drinkable by humans, the process is lengthy and can be costly if the current facilities don’t support the extensive treatments. Instead, many public utilities departments treat the wastewater to a clean but nonpotable state, where it can be used in a variety of ways, such as landscape irrigation.

The district entered agreements with six ranchers in Alpine County in 1988 to supply recycled water, while in 2018, STPUD began growing alfalfa with recycled water at Diamond Valley Ranch. Biosolids from the recycling process are also used as fertilizer in Douglas County through partner Bently Agrodynamics. Lastly, the recycled waters flow 2,200 feet from the top of Luther Pass down to Alpine County—a process harnessed to produce 381,000 kilowatts of hydroelectricity annually.

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However, the rancher agreements are set to expire in 2028. Along with other considerations such as the infrastructure and costs of the department, this sparked STPUD in 2021 to work on developing a strategic plan to decide what actions to take in order to treat, store, and distribute recycled water in the future. To develop the plan, STPUD paired with several partners, including Carollo Engineers. The vice president of Carollo, Elissa Garvey, presented the information regarding the plan at the meeting.

As it stands, the current operation and maintenance of STPUD’s facilities is $6 million, with $1.2 million going towards export costs. The strategic plan explored eight different alternatives in how they handle wastewater, which involved interstate discussion and conversations with the Washoe tribe. The alternatives included expanded disinfected secondary-23 delivery at Alpine, expanded disinfected tertiary reuse at Alpine, discharging the water to West Fork in Carson, reuse of water in Nevada via discharge to Indian Creek, reuse in Nevada via discharge to Mud Lake, indirect potable reuse in Nevada, expanded reuse in Nevada via direct delivery, and treated effluent conveyance to Douglas County Lake Tahoe Sewer Authority (DCLTSA) for reuse in Nevada.

STPUD and its partners developed a flowchart and decision tree for which alternatives to pursue, after performing a multi-criteria analysis. If there is sufficient recycled water capacity and no other triggers to change, the department will stay with its current system.

If, however, there is insufficient recycled water capacity because, for example, the rancher agreements change, the alternative is to look for other parcels to replace their lost capacity. This would be the alternative to have expanded disinfected secondary-23 delivery in Alpine County, where the water could be used for pastureland for animals, restricted landscape irrigation, or be stored through landscape impoundment, which would cost approximately $18 million.

This plan also gave STPUD the chance to consider system modifications that could be implemented with different alternatives. While the development of urban fire protection system and the use of tunnelling to eliminate elevation changes were considered, they were ultimately struck from consideration.

However, the STPUD is looking into split treatment (where the water treatment process is split between locations), export system energy recovery, and constructed wetlands.

The export system energy recovery would help with the issue of pumping water over elevations and would include either a Pelton wheel at the base of the C-line or a series of pumps as turbines along the C-line. According to Julie Ryan, the current engineering department manager at STPUD, the C-line is already nearly 50 years old, so investigating and possibly replacing its infrastructure would be beneficial in the long run. These would cost the STPUD either $123 million for the Pelton wheel or $52 million for the series of pumps. However, the DCLTSA, if interested, could combine their export line with STPUD’s export lines, bringing the cost down to $45 million for the Pelton wheel and $40 million for the series of pumps.

Constructed wetlands would provide additional capacity for recycled water storage, according to the report—which is especially important when there are periods when release from Harvey Place Reservoir is prohibited. The report says, “wetlands may be designed to also provide water quality polishing, wetland habitat/ecological benefits, and possibly be used as a wetland mitigation bank.” The wetlands could provide up to ten extra days of storage.

“We have arrived at a point where we are much more certain we are doing the right thing,” said Ryan, during the Q&A portion of the event. She indicated that while possible that they might switch to them in the future, the viable alternatives still had major infrastructural and economic costs, which she was glad they now had a better understanding of through the research in the plan. “We can also focus on things like addressing the aging infrastructure needs and improving resilience through constructed wetlands.”

Garvey said that this public comment phase is primarily to ensure that people understand the strategic plan, express whether or not it makes sense, and to clarify the trigger system that would cause STPUD to switch to alternatives.

The STPUD is currently discussing the rancher agreements and addressing ongoing litigation regarding the operations at Alpine County. One of the stakeholders indicated that the outlook seemed good and was leaning towards a positive resolution.

The comment period for the strategic plan is open from October 24 to November 11 on the STPUD website. Ten days after the comment period closes, the STPUD will have its official board meeting on November 21.

Eli Ramos is a reporter for Tahoe Daily Tribune. They are part of the 2024–26 cohort of California Local News Fellows through UC Berkeley.