The Menlo Park Tritium Laboratory

Menlo Park Tritium Laboratory equipment.

Welcome to the Menlo Park Tritium Laboratory. We provide tritium analysis for customers within the United States Geological Survey. We accept samples as raw unfiltered water (see sampling instructions document for sample collection instructions), and prepare them for analysis through distillation and electrolytic enrichment. Tritium in the concentrated samples is then measured using liquid scintillation counters. Samples with very high tritium may not need enrichment, and can be measured directly on the scintillation counters. Sample size is based on the required 1 sigma detection limit, please see below for the list of sample sizes and laboratory codes.

Contact Us

Samples should be sent to:
Attn: Doug Choy
US Geological Survey
345 Middlefield Dr. MS 434
Menlo Park, CA 94025

For general questions and inquiries regarding methods, research, and existing data, contact:
Megan Young | 650-329-4544 |

For routine sample submission or questions regarding recently shipped samples, contact:
Doug Choy | 650-329-4316 |

Forms and Instructions

NAWQA samples only: NAWQA tritium submission form and specific sampling instructions are located in Age Dating Information – Menlo Park Tritium Lab section at:

Sample Collection and Submission

Please refer to the following forms when submitting samples:

Please be aware that we require a completed electronic sample submission sheet in order to log-in tritium samples and assign laboratory ID numbers. Completed electronic sample submission sheets can be sent directly to Doug Choy ( All samples are placed into the analytical queue according to the date we receive the electronic sample submission sheet, not the sample arrival date. If we already have the electronic sample submission sheet, your samples will be entered into the analytical queue immediately upon arrival at the tritium laboratory.

We recommend collecting samples in HDPE "plasticware cyclinders" bottles, which are usually available from the USGS one stop shop and multiple scientific suppliers. However, any type of plastic bottle with threaded cap which can be sealed to completely prevent evaporation and direct sample loss and which will survive shipping can be used.

Inspect sample bottles to insure that they are clean and dry. Bottles must be completely dry, laboratory-pure water may contain measureable tritium. Fill bottle near to top. No need to rinse or add any preservatives. Cap bottle and seal cap with parafilm or electric tape. Label bottle with the following:

  • Name or designation of sample
  • Date of collection
  • Time of collection

Make sure the information on the bottle labels matches the information on the sample submission form. It is a good to tape the label on the bottle. If sample is highly saline, that information should be included on sample bottle. Samples should be shipped directly to the tritium laboratory. Please do not chill samples. Include a printed copy of the submission sheet inside the cooler. Pack samples securely in a cooler and ship them to:

Attn: Doug Choy
US Geological Survey
345 Middlefield Dr. MS 434
Menlo Park, CA 94025

Please send the completed electronic sample submission sheet to Doug Choy ( either before or at the same time as the samples are shipped. Samples can only be entered into our tracking system and placed into the analytical queue when we have both the electronic sample submission sheet and the samples.

Sample coolers will be returned to the sender by regular mail. Please include a printed copy of the appropriate return address inside the cooler along with the printed sample submission spreadsheet. Since many coolers look alike, we recommend marking the outside of your cooler with your name, lab designation, or Water Science Center designation.

Billing and Data Management

Prices and Detection Limits

The Menlo Park Tritium Laboratory will use QWDX to enter sample information and data into NWIS in place of the NWQL. Results are entered into QWDX as soon as each sample analysis is completed. Sample information (USGS Site ID, collection date and time) is copied directly from the electronic sample submission sheet to ensure consistency and easy data retrieval.

Billing for samples is handled by the Menlo Park Tritium Laboratory, which will generally be in the form of a request for an SV for services. Samples are billed when we receive the electronic sample submission sheet. Please contact Megan Young ( for special billing requests (pre-pay or delayed billing, etc).

Sample Sizes and Detection Limits

NWIS Code Previous NWQL Code 1 Sigma Detection Limit Bottle Size
LSC11 452 13 picoCuries/L 125 ml
LSC05 460 2.2 picoCuries/L 250-500 ml
LSC04 624 1.3 picoCuries/L 0.5 – 1 L
LSC14 1565 0.5 picoCuries/L 1 L

Sample code LSC11/452 is for direct liquid scintillation counting of samples with high tritium. All other sample codes include distillation and electrolytic enrichment prior to liquid scintillation counting. USGS prices for FY15 and FY16-17 are listed in the Prices and Detection Limits document.