Great Lakes Water Quality Monitoring and Surveillance Data

Map and Visualize

Water quality and ecosystem health data are collected in the Great Lakes to determine baseline water quality status, long term trends and spatial distributions, the effectiveness of management actions, determine compliance with water quality objectives and identify emerging issues are included in this dataset

Version 5.1.0
Data Steward Email
Data Collection Organization Environment and Climate Change Canada (ECCC) / Environnement et Changement climatique Canada (ECCC)
Data Upload Organization Environment and Climate Change Canada (ECCC) / Environnement et Changement climatique Canada (ECCC)
Progress Code onGoing
Maintenance Frequency Code asNeeded
Data source URL
Topic Category Code inlandWaters
Keywords Water quality, Great Lakes, Surveillance, Monitoring, Ontario, Erie, Superior, Huron, Georgian Bay, nutrients, contaminants
Spatial Extent -92.054° 41.469°, -76.122° 48.757° (W S, E N)
Vertical Extent -359 m to 0 m
Temporal Extent 2000-04-16 to 2023-05-19
Date Published
Alternate Formats FGP-HNAP ISO:19115-2 (XML) , W3C DCAT (XML) , W3C DCAT (JSON-LD)


Environment and Climate Change Canada (ECCC) / Environnement et Changement climatique Canada (ECCC). 2024-06-06. "Great Lakes Water Quality Monitoring and Surveillance Data" (dataset). 5.1.0. DataStream.

Funding Sources

Government of Canada

Data Collection Information

Ship-based surveys are conducted during spring and summer seasons on the Great Lakes. The number of stations ranges from 50-100 per lake but varies based on program requirements and field constraints. Primarily using the Canadian Coast Guard Ship (CCGS) LIMNOS, whole water and filtered samples are collected from various depths; surface, multi-depth discrete, and integrated from surface to 2 m above bottom. Cruises are conducted on Lakes Ontario, Erie, Huron, and Superior as well as Lake Huron. Sampling instruments include a multi-bottle array (Rosette) or single bottle samplers (Van Dorn bottle) for discrete depth samples, an integrator for depth-integrated samples, PoPCart for persistent organic pollutants, and ISOMET for trace metals and mercury.

These water samples are analysed for a broad suite of compounds including nutrients, major ions, physical parameters, trace metals, pesticides and organic contaminants at ECCC’s National Laboratory for Environmental Testing (NLET) in Burlington, ON using methods accredited by the Canadian Association for Laboratory Accreditation (CALA). Additional variables are analysed at other accredited ECCC or external labs. The most recent variable and methods table can be downloaded here:

Selected methods and recent results published in:
Dove, A., S.M. Backus and K. Sharp King, 2021. Tritium in Laurentian Great Lakes Surface Waters, Journal of Great Lakes Research.
Dove, A. and S.C. Chapra, 2015. Long-term trends of nutrients and trophic response variables for the Great Lakes. Limnology and Oceanography. 60(2): 696-721.
Venier, M., A. Dove, K. Romanak, S. Backus and R. Hites, 2014. Flame Retardants and Legacy Chemicals in Great Lakes Waters. Environmental Science and Technology 48(16): 9563−9572.
Chapra, S.C., A. Dove and G.J. Warren, 2012. Long-term trends of Great Lakes major ion chemistry, Journal of Great Lakes Research 38: 550-560. doi:10.1016/j.jglr.2012.06.010
Dove, A., B. Hill, P. Klawunn, J. Waltho, S. Backus and R.C. McCrea, 2012. Spatial distribution and trends of total mercury in waters of the Great Lakes and connecting channels using an improved sampling technique, Environmental Pollution 161: 328 - 334,
Dove, A., 2009. Long-term trends in major ions and nutrients in Lake Ontario, Aquatic Ecosystem Health Management 12(3): 281-295.

Data Processing

As part of quality assurance procedures, replicate samples are collected by sequential sampling for each container type. Field blanks are processed by prefilling sampling bottles with ultra-trace clean (MilliQ) water in the laboratory and subjecting them to field handling, travel, and laboratory processes.
Values reported below the detection limit (i.e., trace values) and samples with undetected concentrations (i.e. left censored values) are denoted with a “T” flag and “L” flag respectively.

Open Government Licence (OGL)

See disclaimer for details.

Data Disclaimer

Environment and Climate Change Canada employs every reasonable effort whenever feasible, to ensure the currency, accuracy and precision of the information provided. However, there are some limitations due to the sources of the data and the technology used in its processing and management. Furthermore, the material or any data derived using the data is subject to interpretation. Users are responsible for verifying that the supplied material is appropriate for the use or application for which they wish to employ it. The water quality and aquatic ecosystem data released may include provisional and/or validated data. Provisional data should be considered with greater caution as it has yet to be validated with quality control and quality assurance activities, which may result in significant change made to the data. Environment and Climate Change Canada makes no representation or warranty of any kind, either expressed or implied, as to the information presented, nor as to its fitness for any particular use. Environment and Climate Change Canada does not assume nor accept any liability arising from any use of the information and applications used to display or use the information. The data are not intended for any legal, or navigation purposes. The data may change from time to time as updated information is received. If any information seems to be incorrect, raises concerns, or for more information on this data, please communicate with the Environment and Climate Change Canada contact provided within the application. The material might contain links to third party sites. Environment and Climate Change Canada provides these links only as a service and convenience. Environment and Climate Change Canada takes no responsibility for the content at third party sites and in no way implies an endorsement or recommendation of the products, services or information found there. A third party site may have a privacy policy different from that of Environment and Climate Change Canada. Environment and Climate Change Canada does not assume nor accept any liability arising from any use of third party sourced content.

API Access

curl -G --data-urlencode "\\$filter=DOI eq '10.25976/6fgn-0915'" -H "x-api-key: PRIVATE-API-KEY"



Added new 2023 measurements

Schema v2.20.1
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File size 1.79 MB


Update to metadata


Updated with 2022 observations

Schema v2.18.1
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Added new data from the 2021 Surveillance cruises

Schema v2.6.12
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Replaced the truncated latitude/longitude from the original file

Schema v2.6.4
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Added missing Water Quality Cruise data

Schema v2.6.2
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File size 50.33 MB


initial submission

Schema v2.6.1
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File size 34.91 MB