Marine Water photo

Marine Water Quality Monitoring

On this page you will find detailed information and additional links to our Marine Flight Program.

PROGRAM INFORMATION:

Long-Term Marine Water Quality Monitoring

We conduct monthly marine water quality monitoring at stations in Puget Sound, Grays Harbor and Willapa Bay. Data are collected from 39 core stations and approximately 2-5 rotating stations annually. The marine flight program is part of the Puget Sound Ecosystem Monitoring Program (PSEMP).

Why Monitor Marine Water Quality?

The Marine Waters Monitoring program measures ambient water quality indicators to:

  1. Support the administration of section 303d of the Federal Clean Water Act. Data are assessed against water quality standards and this assessment results in a regulatory listing of impaired water bodies throughout the state.
  2. To establish baseline conditions with the goal of detecting water quality changes within the context of complex estuarine gradients and processes, using the Marine Water Condition Index.
  3. Supporting interdisciplinary efforts aimed at assessing the health of marine ecosystem components. Certain multi-agency efforts also result in the development of marine water quality models which are tools used to inform management decisions.

What Features Are Monitored?

We take vertical sensor profiles measuring the parameters pressure, temperature, salinity, density, dissolved oxygen, light transmission, pH, turbidity, and photosynthetically-active radiation (PAR), using a standard oceanographic instrument package (CTD).

We collect discrete water samples at the surface for chlorophyll a, phaeopigment, nitrate, nitrite, ammonium, orthophosphate, silicate from 0, 10 and 30 meters, along with taking a Secchi disk depth reading.

How Monitoring Is Conducted.

Long-term monitoring is conducted using a Kenmore Air DeHavilland Beaver floatplane, which allows a large geographic area to be sampled in a short amount of time. Four regional surveys are conducted each month to complete sampling throughout the Puget Sound and coastal station network, as weather allows. Approximately 8-11 stations are sampled per survey. Stations are identified by dead-reckoning and verified by a Global Positioning System (GPS) receiver.

Sample collection methods are in compliance with the Puget Sound Protocols and Guidelines and will be detailed in our Quality Assurance Program Plan (QAPP), Bos et al. (in prep). Information on specific sampling protocols and analytical methods can be found in the following sections.

FIELD SAMPLING

CTD Profiler

A Sea-Bird Electronics, Inc. SBE 25 Sealogger CTD (conductivity-temperature-depth) profiling package is used for collecting continuous water column profile data. The CTD is equipped with sensors to measure additional variables and a pump to draw water through the sensors. Profiles at each station are collected from the sea surface (top bin = 0.5 m) to the sea bottom. The CTD and sensors are operated and maintained according to manufacturer’s recommended protocols, with factory calibration occurring annually: Seabird Manual (PDF).

Secchi Disk

Secchi disk depth is used to indicate water clarity and to derive the extinction coefficient of incident light penetration through the water column. More information on secchi disk measurements can be found here: Standard Operating Procedure for Seawater Sampling (PDF).

Seawater Sampling

A 1.7-L Niskin® bottle is used to collect seawater at 0.5, 10, and 30 m. For stations shallower than either 10 or 30 m, a sample at the near-bottom depth (0.5-1 m above the seabed) is taken. Discrete water samples are taken from the Niskin bottle for dissolved nutrients (ammonium-N, nitrate+nitrite-N, orthophosphate-P and silicate), and pigments (chlorophyll a and phaeopigment). Discrete samples for DO and salinity are drawn periodically for comparison with the in situ sensor values. More information on the collection of these samples can be found at: Standard Operating Procedure for Seawater Sampling (PDF).

LABORATORY PROCEDURES

Nutrients

Analyses for dissolved nutrients collected since 19 February 1999 have been conducted by the University of Washington Marine Chemistry Lab for nitrate, nitrite, ammonium, orthophosphate, and silicate following standard oceanographic methods described in Grasshoff et al. (1999), and Strickland and Parsons (1968).

Grasshoff, K., M. Ehrhardt, K. Kremling. 1999. Methods of seawater analysis. 3rd. ref. ed. Verlag Chemie GmbH, Weinheim. 600 pp. Strickland, J. D. H. and T. R. Parsons, 1968. A Practical Handbook of Seawater Analysis. Fisheries Research Board of Canada, Bulletin 167, 71–75.

Strickland, J. D. H., and Parsons, T. R. 1968. A Practical Handbook of Seawater Analysis. Ottawa: Fisheries Research Board of Canada, Bulletin 167. Pp. 23-28.

Chlorophyll a

Samples for chlorophyll a and phaeopigment are analyzed for by Marine Waters Monitoring staff according to EPA method 445.0, Standard Operating Procedure for Chlorophyll a Analysis (PDF).

Dissolved Oxygen

The discrete samples for DO are analyzed by Marine Waters Monitoring staff using the Carpenter modification of the Winkler method for seawater, Standard Operating Procedure for Seawater Dissolved Oxygen Analysis (PDF).

Salinity

Discrete salinity samples are analyzed by University of Washington Marine Chemistry Laboratory using standard oceanographic methods described in Grasshoff et al. (1999), and Strickland and Parsons (1968).

Grasshoff, K., M. Ehrhardt, K. Kremling. 1999. Methods of seawater analysis. 3rd. ref. ed. Verlag Chemie GmbH, Weinheim. 600 pp. Strickland, J. D. H. and T. R. Parsons, 1968. A Practical Handbook of Seawater Analysis. Fisheries Research Board of Canada, Bulletin 167, 71–75.