The Laboratory performs tests on water, wastewater, and soils. Samples are collected from a wide variety of sources. In the Tahoe Basin, samples are collected from the wastewater treatment plant; streams and monitoring wells; drinking water wells, storage tanks, and customers homes. In Alpine County we collect samples from reservoirs; streams; groundwater; wells at ranches, schools and businesses on lands that use our reclaimed water for irrigation.

For information on Lead Sampling in Local Schools click here

Wastewater Treatment Plant

Each day samples are taken of the influent, effluent and the treatment processes. Close to 3,000 samples are collected and 17,000 tests run each year to assure the recycled water meets requirements. The treatment plant has been in 100% compliance since 1995.

Drinking Water

The Lab collects 20-40 samples each week from wells, storage tanks, dedicated sample taps and customers' homes. These samples are tested for bacteria, chlorine and temperature to assure that only safe high quality water is delivered to our customers.

Our wells are sampled every year and analyzed for all required tests and some unregulated ones, even though the state requires less frequent monitoring. Some of the tests performed are metals, minerals, uranium, radon, up to 60 volatile organic chemicals (ie: chloroform, MTBE, and benzene) and bacteria. Results of the annual testing on each of our wells can be found at the Water quality page.

Our consumer confidence report, giving the average and range of values for detected compounds in our distribution system and at the wells can be found here.

Why add chlorine? It makes the water taste funny: The District began adding chlorine to the drinking water in 1989. This is done to reduce contamination of your water by bacteria.

Alpine County Program

The purpose of the Alpine County monitoring program is to assess the effects of using our recycled water to irrigate Alpine County ranchlands. To accomplish this, extensive monitoring is performed on Alpine County ground waters, surfacewaters and soils. Samples of soils and well water are taken from all the ranches receiving recycled water for irrigation. Stream samples are taken from the West Fork Carson River, upstream, midstream and downstream of the areas irrigated with our water. The District also installed special monitoring wells at areas that could immediately show any groundwater impact from our recycled water. Some sites are outside the area receiving recycled water to act as study controls. The sample sites were chosen in cooperation with the Lahontan Regional Water Quality Control Board, National Resources Conservation Service, and District design engineers. Sample sites and types of analyses are periodically reviewed and modified.

Close to 10,000 tests are performed each year on Alpine County water and soil samples. Most of the analyses are conducted in our own laboratory. The tests include nutrients, minerals, solids, metals, algae, and bacteria. Analyses for some toxic metals and many organic chemicals are performed by independent state certified laboratories. The District Laboratory collects 30-40 samples each month from the following areas:

Sample Type # Samples Frequency
Streams 8 to 10 Monthly
Irrigation Ditches 5 Monthly
Ranch Wells 4 Quarterly
Monitoring Wells 26 Quarterly
Soils 6 Quarterly
Harvey Place Reservoir 1 Monthly
Indian Creek Reservoir* 6 Monthly
* No longer used for recycled water
Lab technician in the field
Lab technician in the field
Lab technician in the field
Lab technician in the field

Indian Creek Reservoir

Indian Creek Reservoir (ICR) was built to receive tertiary treated reclaimed wastewater from the late 1960s till 1989. During that time it provided a home to rainbow trout and was a great year-round fishery. All reclaimed wastewater is now stored in our Harvey Place Reservoir during the winter months. ICR currently receives no reclaimed water, getting its water from the West Fork Carson River and Indian Creek stream. It still is a great year-round trout fishery.

Monitoring is done at ICR in response to Total Maximum Daily Loads (TMDL) planning and to assist Fish & Game with fishery management. The Lab performs profiling at ICR each month. An electronic data sonde is sent through the water column at three sites. The sonde records depth, temperature, pH, electrical conductivity and dissolved oxygen. The data is downloaded to a computer and the results tabulated and graphed. The results are then e-mailed to the California Dept of Fish & Game. Water samples are also taken at three depths and analyzed for nutrients, minerals, metals, chlorophyll, algae and bacteria. Graphs showing temperature and dissolved oxygen (DO) in winter and summer are shown below.


November 2000

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August 2001

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Quality Assurance

Quality assurance is a major part of the laboratory routine. Each time a test is run, 10 - 20 percent of the samples analyzed are standards, duplicates, and interference checks. Each test is subjected to a statistical evaluation of accuracy and precision. A test is re-done if the result falls below acceptable levels or is not within trend values. The analysts who perform the tests are certified by both the American Water Works Association and the California Water Environment Association. Our laboratory is certified by the California Environmental Laboratory Accreditation Program.

Laboratory Tests

The District's Lab uses both manual and automatic methods to analyze nutrients, metals, minerals, and solids. Many test methods (nutrients and metals) are capable of detecting in the parts-per-billion (ppb) range. The lab is equipped with several computer controlled instruments that can run un-attended. Some instruments can perform multiple analyses on up to 50 samples an hour. Automatic methods enable better quality control and reduces the amounts of hazardous waste that requires disposal. Bacterial tests for total coliform, E.coli, and fecal streptococci are also performed.

The parameters used most to determine recycled water influence on natural waters are nitrates, ammonia, phosphorous, chlorides, and total dissolved solids (TDS). The data is tabulated and plotted to determine any trends. The Laboratory is certified by the State of California to perform drinking water and wastewater tests. Some of the tests the Lab performs are listed in the table below.

Microbiology Minerals / Demand Nutrients Physical Tests Metals
Coliforms Alkalinity Ammonia Color Arsenic Magnesium
E. coli Boron Kjeldahl Nitrogen Electrical Conductivity Barium Manganese
Fecal Coliforms Chloride Nitrate Odor Calcium Potassium
Fecal Streptococci Chlorine Nitrite pH Copper Silver
Plate counts Hardness Phosphate, ortho Suspended Solids Iron Sodium
  Sulfate Phosphorous, total Turbidity Lead Zinc
  BOD   Total Dissolved Solids   .
. COD   . . .

Look for the Lab's white truck. You'll see the technicians getting samples from the streams, fields, school, stores, and restaurants throughout South Lake Tahoe and eastern Alpine County. Stop by if you have any questions.


Name Role Contact
Dan ArceLab
Brian ChernagoLab
(Vacant)Lab Technician
Delores TrebotichLab
Mariola IzzardLaboratory Assistant –
Sierra KortgeLaboratory

For more information, call us at 530-544-6474, ext 6231 or e-mail us with your questions.