Member Case Study – June 2018

  • by Will Holbert
  • Jun 15, 2018
  • Newsletters

Nothing Goes to Waste in South Tahoe Public Utility District’s Wastewater Treatment Operation

Everyone knows what runs downhill, but the South Tahoe Public Utility District knows how to recycle it into 381,000 kilowatts a year.

Known for its blue waters, incredible depth, and endless recreation opportunities, Lake Tahoe attracts around 3 million visitors each year.  With a population of 21,000, South Lake Tahoe is the largest city in the Sierra Nevada range. Supplying most of the drinking water and all of the sewage collection and treatment is the South Tahoe Public Utility District (STPUD).

A turbine and supervisory control and data acquisition system inside STPUD’s Hydroelectric Building.

Last year, STPUD became the first wastewater district in the Lake Tahoe Basin to produce its own hydroelectricity. How did a wastewater treatment plant get into the energy business? It all started back in 1969, when every wastewater district around Lake Tahoe was required by law to export treated wastewater out of the Tahoe Basin to keep Lake Tahoe blue.  As such, STPUD pumps all of South Lake Tahoe’s treated wastewater — an average of 3.9 million gallons per day (MGD) — 26 miles to Alpine County, where it’s used by ranchers for irrigation and by STPUD to grow grain for livestock on its own 1,400-acre Diamond Valley Ranch.

Pumping the treated wastewater up the Sierra Nevada requires an enormous amount of energy, but once it reaches the top, 2,200-feet of gravity takes over. Harnessing the resulting water pressure wasn’t a new idea for STPUD, and similar systems operate throughout the world. But it fulfilled a long-standing goal for the district, which prides itself on innovative environmental stewardship. However, cost-benefit analyses of investing in renewable energy didn’t pencil out until recently.

“It’s something we’ve been dreaming about for a long time, but have been waiting for it to make financial sense,” said Shelly Thomsen, the district’s water conservation specialist. “How can we capture energy that would otherwise be wasted?”

In November 2017, STPUD made that goal a reality. Today, at the bottom of Luther Pass on Diamond Valley Ranch inside a small and unassuming building is a hydroelectric turbine, which Thomsen compared to a large hot tub motor.  As the water moves from high to low elevation, pressure builds in the pipe. The turbine converts that pressure into electricity via a generator next to the pipe. The district currently produces and returns to the grid around 381,000 kilowatts of renewable energy each year, enough to power about 55 homes. It also saves 100 tons of the greenhouse gas carbon dioxide from entering our atmosphere every year.

That’s not the only way the district takes the waste out of wastewater.

In addition to recycling 100% of its wastewater, the district also recycles 100% of its biosolids as fertilizer for agricultural land with Bently Agrodynamics in Douglas County, Nevada. This small wastewater plant in the Sierra Nevada range is one of only a handful of wastewater agencies in the world that can claim 100% re-use of both recycled water and biosolids.

A pivot-rig irrigating with recycled water at Diamond Valley Ranch.

The district’s venture into renewable energy stems from a history of innovation. Back in 1963, the district hired CH2M Hill — now Jacobs — to study possible methods to treat and dispose of sewage.  Small scale tests were begun to determine if a treatment process that had never been applied to municipal wastewater could provide a treated water quality adequate to support a recreational reservoir in Alpine County. The tests were successful and a full-scale 2.5 MGD tertiary water reclamation plant was placed into service in 1965. During this period of operation, the district hosted many international visitors who came to observe and learn state-of-the-art wastewater reclamation. The technology created in South Lake Tahoe has since been used throughout the world.

Today, STPUD treats wastewater to filtered secondary, instead of the tertiary treatment originally designed, because ranchers using the recycled water want the added nutrients for their farmland. Now, the small water and sewer district in beautiful South Lake Tahoe continues to make waves as it embarks on its first venture producing hydroelectricity.

Suggested Resources

15 RESOURCES prev next
ACWA 2018 Fall Conference Presentations

Presentations from ACWA’s 2018 Fall Conference & Exhibition held Nov. 27-30 in San Diego are available below. Please note that […]

2018 Summary of Legislation

ACWA’s 2018 Summary of Legislation provides concise information on legislation enacted in the second year of the 2017-’18 legislative session that […]

California H2O: Flowing for the Future

ACWA and J Comm, Inc. have collaborated to create a 10-part video series to educate Californians about critical water issues. […]

ACWA’S 2018 Fall Legal Briefing and CLE Workshop Materials

The following presentations and materials for ACWA’s 2018 Legal Briefing and CLE Workshop on Nov. 27 from 9 a.m. to […]

Comments on 2018 Electronic Annual Reporting

Agency: State Water Resources Control Board Subject: 2018 Electronic Annual Reporting Letter excerpt:  We appreciate your efforts in convening the Division of […]

2018 Summary of Appellate Cases

ACWA’s  2018 Summary of Appellate Cases details court decisions in 2017-’18 that may be of interest to ACWA member agencies […]

November 2018 Federal Regulatory Issues Chart

ACWA’s November 2018 Federal Regulatory Chart, is now available. This chart details the status of federal regulatory issues being tracked by […]


Sorry, but only ACWA members have permission to view this content. Member login is required.

Bay-Delta Plan Update Toolkit

Sorry, but only ACWA members have permission to view this content. Member login is required.

ACWA 2018 Regulatory Summit Presentations

ACWA’s 2018 Regulatory Summit was held on Oct. 16, 2018 at the Hilton Arden-West in Sacramento. The theme of this […]

Comments on Low-Income Water Rate Assistance Program Implementation

Agency: State Water Resources Control Board Subject: Implementation of Low-Income Water Rate Assistance Program Letter excerpt:  The Association of California Water Agencies […]

Joint Comments On Making Water Conservation a California Way of Life: Primer

Agency: Department of Water Resources Subject: Making Water Conservation a California Way of Life: Primer of 2018 Legislation on Water […]

August 2018 Federal Regulatory Chart

Sorry, but only ACWA members have permission to view this content. Member login is required.

Toolkit Available for Supporting, Educating About Proposition 3

Sorry, but only ACWA members have permission to view this content. Member login is required.


California’s second annual Water Professionals Appreciation Week will kick off Oct. 6, highlighting the important role of water industry professionals […]

Suggested News

15 Articles prev next
ACWA Launches “California H2O: Flowing For the Future” Video Series to Promote California Water Industry

ACWA has developed the first three episodes of a new educational video series to help member agencies inform their customers, […]


COMMERCE – The Central Basin Municipal Water District is proud to announce that residents and businesses in our service area […]

Two CVWD projects selected to receive EPA federal loans

COACHELLA – Two Coachella Valley Water District (CVWD) stormwater projects have been selected to receive Environmental Protection Agency (EPA) federal […]

State Water Project Begins Year with 10 Percent Allocation

On Nov. 30, the California Department of Water Resources (DWR) announced an initial allocation on the State Water Project (SWP) […]

Award Winners on Display at ACWA’s 2018 Fall Conference in San Diego

SAN DIEGO – Today, the Association of California Water Agencies (ACWA) handed out awards in several categories to water agencies and individuals […]

ACWA Awards Graduate Scholarship for 2018-’19 Academic Year

SAN DIEGO – The Association of California Water Agencies (ACWA) today announced the winner of its 2018-’19 Stephen K. Hall Water […]

New PWD Water System Master Plan, Associated Fees Approved

PALMDALE – A new Water System Master Plan that projects infrastructure needs through 2030, including updated Capital Improvement and Water Supply […]

Central Basin Recognized for Excellence In Information Technology

COMMERCE – The Central Basin Municipal Water District has once again been recognized for information technology practices that excel in […]

EMWD Announces 2018 Water Champion Award Recipient

PERRIS — Eastern Municipal Water District (EMWD) today announced that Assemblywoman Anna Caballero was selected for its 2018 Water Champion […]

Operation FATFISH

A recent ACWA event jointly hosted by Region 2 and Region 4 vividly illustrated the value behind functional flows and […]

November/December Priority Issues Update

The November/December 2018 Priority Issues Update is now available online to members. The update is bullet-style summary of the latest […]

PWD, Partners Break Ground at Recharge Project Site

PALMDALE – Palmdale Water District (PWD) officials joined the City of Palmdale, California Department of Water Resources and other local […]

New Assistant General Manager Named for Elsinore Valley Municipal Water District

LAKE ELSINORE – Elsinore Valley Municipal Water District (EVMWD) named Brian Macy, P.E., seasoned water and engineering industry leader, as […]

Western’s Communications Programs Take Home Top Honors

RIVERSIDE – Western Municipal Water District (Western) received nine top honors from the Public Relations Society of America-Inland Empire Chapter […]


ROWLAND HEIGHTS– The Rowland Water District Board of Directors has released the details of its latest, comprehensive Strategic Plan, which […]