Environmental Surveillance Laboratory Branch

The CNMI DEQ’s Environmental Surveillance Laboratory protects public health and the environment by measuring the quality of water used by the public for drinking, recreational and/or other purpose. This branch is responsible for implementing proper quality control practices in day-to-day tasks and that reported data are precise, accurate, valid and defensible.


The Division of Environmental Quality Surveillance Laboratory (DEQ ESL) was established by the Commonwealth of the Northern Mariana Islands to provide monitoring data required under the Safe Drinking Water Act (P.L. 93-253), Clean Water Act (CWA) and other environmental programs.

The data generated by the Laboratory are used to evaluate the quality of drinking and recreational waters in the Commonwealth. The elements of a basic quality control program are well defined by federal statutes.

The manual best describes an overall program that meets and in some instances exceeds these requirements.

Although the success of the program depends upon the training, professional pride and awareness of each individual technician, final responsibility for the reliability of reported analytical results rests with the Environmental Surveillance Laboratory (ESL) Manager.

The ESL Manager is responsible for review of the implementation of the plan and its requirements.

The Microbiology and Chemistry Section Heads will be responsible for conducting mock on-site audits of their areas under the guidance of the ESL Manager using prepared check-off lists.

The mock audit results are then reviewed by the ESL Manager who is responsible for instructing staff in how to rectify any deviations or deficiencies noted during the audit.

PWS/PRODUCT WATER TEST Total Coliform/E.coli $ 50.00
Total $ 50.00
BI-ANNUAL WELL TESTING/PUMP TEST Total Coliform/E.coli $ 50.00
pH 20.00
Total Dissolved Solids 20.00
Conductivity 20.00
Chloride 35.00
Hardness 35.00
Total Nitrate + Nitrite 40.00
Total $ 220.00
BRINE WATER TEST Total Coliform/E.coli $ 50.00
pH 20.00
Total Dissolved Solids 20.00
Conductivity 20.00
Chloride 35.00
Total $ 145.00
WASTE WATER TEST Fecal Coliform $ 50.00
pH 20.00
Total Suspended Solids 20.00
Turbidity 20.00
Total Nitrate + Nitrite 40.00
Total $ 150.00
OTHER TEST Free Residual Chlorine $ 20.00
Total Residual Chlorine 20.00
Turbidity 20.00
Temperature 10.00
Dissolved Oxygen 20.00
Salinity 20.00

Capabilites and Certification


The DEQ laboratory tests several microbiological and chemical parameters in drinking, recreational, and other surface waters. Microbiological parameters include: Total Coliforms, Escherichia Coli, Fecal Coliforms and, Enterococci. Chemical parameters include: pH, Turbidity, Conductivity, Chlorides, Hardness, Residual chlorine (Total and Free), Temperature, Total Dissolved Solids, Total Suspended Solids , Nitrate and Orthophosphates.


All Drinking Water Certified Laboratories, including the DEQ Environmental Surveillance Laboratory Program must be fully certified by the U.S. Environmental Protection Agency (USEPA) Region 9, in order for the laboratory to carry out its tasks in analyzing drinking water in the CNMI. The DEQ laboratory is currently certified for bacteriological analysis using Colilert-18 (Standard Method 9223B) and EPA 353.2 Method - Nitrate and Nitrite as N, Nitrate as N, Nitrite as N.

Colilert -18 ( Standard Method 9223B ) is an enzyme substrate test utilizes hydrolyzable substrates for the simultaneous detection of total coliform bacteria and Escherichia coli enzymes. When the enzyme technique is used, the total coliform group is defined as all bacteria possessing the enzyme β-D-galactosidase, which cleaves the chromogenic substrate, resulting in release of the chromogen. Escherichia coli are defined as bacteria giving a positive total coliform response and possessing the enzyme β-glucuronidase, which cleaves a fluorogenic substrate, resulting in the release of the fluorogen.

Colilert-18 is similar to the original Colilert method: the chromogenic substrate ortho-nitrophenyl-β-D-galactopyranoside (ONPG) is used to detect an enzyme produced by coliform bacteria. Samples containing coliform bacteria will hydrolyze the ONPG substrate to release a yellow-colored compound. E. coli are detected by using the fluorogenic substrate 4-methylumbelliferyl-β-D-glucuronide (MUG). Samples containing E. coli bacteria will hydrolyze the MUG substrate to produce a fluorescent compound when viewed under long-wavelength ultraviolet light. This combination of substrates allows detection of both total coliforms and E. coli after an incubation period of 18 to 22 hours at 35°C. (The original Colilert method requires a minimum incubation time of 24 hours.) According to the manufacturer, Colilert-18 can detect 1 CFU/100mL with as many as 2 million heterotrophic bacteria/100mL present.

EPA 353.2 Method : The Nitrate (NO3) is quantitatively reduced by passage of the sample through a copperized cadmium column. The nitrite, reduced nitrate plus original nitrite ( NO3 + NO2 , or NOX) is then determined by diazotizing with sulfanilamide followed by coupling with N(1-napthyl) ethylenediamine dihydrochloride. The resulting water soluble dye has a magenta color which is read at 520 nm. Nitrite alone also can be determined by removing the cadmium column.

Nitrate (NO3) and Nitrite ( NO2) as N are measured by Flow Injection Analysis (FIA) using LACHAT Quikchem 8500 Series 2 . It is based on the injection of a liquid sample into a moving, non-segmented continuous carrier stream of a suitable liquid. The injected sample forms a zone, which is then transported toward a detector that continuously records the absorbance electrode potential or other physical parameter as it continuously changes due to the passage of the sample material through the flow cell.


The DEQ ESL is receiving marine water, drinking water and other types of water samples. It also receives water samples collected by Public Water System (PWS) and citizen's complaint for analysis.

Following are schedule of analysis based on sampling and receiving schedules:


MARINE WATERS: Weekly, Alternating eight (8) consecutive weeks, and on a monthly basis.

DRINKING WATERS: Occasionally upon request.

BOTTLED WATER (from ice and water plants): Monthly.

OTHER (waste, runoffs, ground water, rain, swimming pools, wetlands and streams): Occasionally upon request.


PUBLIC WATER SYSTEMS: Monthly, quarterly, and based on requirements under the CNMI Safe Drinking Water (SDW) regulation.

GROUND WATERS (deep wells): Semi-annually and based on permit requirements under the CNMI well drilling and well operation regulation.

OTHERS (OSHA, waste waters): Based on clients requirement and DEQ waste water requirement.

Sampling Locations: Marine Water (Tinian Island, Rota Island, Managaha Island, Saipan Island) and
Drinking Water [bottled water] (all CNMI ice and water plants)

Capabilities and Certification

There are currently four (4) DEQ certified water laboratories. See below for contact information.

CNMI Division of Environmental Quality

  • Charito G. Bautista, ES Laboratory Manager
  • P.O. Box 501304 Saipan, MP 96950
  • (670) 664-8520 (phone)(670) 664-8540 (fax)

Commonwealth Utilities Corporation

  • Heidi Yelin, Laboratory Manager
  • P.O. Box 501220 Saipan, MP 96950
  • (670) 322-5140 (phone) (670) 322-9385 (fax)

Eurofins Analytical, LLC

  • Colin Walters, President
  • 750 Royal Oaks Drive, Suite 100, Monrovia,
  • Monrovia CA 91016
  • (626)386-1100 (phone)

Quality Water, Inc.

  • Rose R. Gamier, Laboratory Supervisor
  • PO Box 502399 Saipan, MP 96950
  • (670) 233-8002 (phone)


DEQ ESL send invitation to participate in Lab tours specifically for the school community: An annual Lab Tour is usually held every April of the month to celebrate the Environmental Awareness month. You may also send your request to have a Lab Tour. If you are interested in participating, please fill out the forms below and send it back to our office via e-mail: or in person.


Laboratory Staff

  • Chat G. Bautista, Environmental Surveillance Laboratory Manager
  • Email address:
  • Contact No. (670)664-8520
  • Cassandra M. Mangarero, FIA Laboratory Specialist
  • Email address:
  • Contact No. (670)664-8542
  • Melvin S. Piteg, Environmental Specialist
  • Email address:
  • Contact No. (670)664-8542
  • Jaime Q. Reyes, Environmental Specialist
  • Email address:
  • Contact No. (670)664-8542