Ministère de l'Environnement
et de la Lutte contre les changements climatiques
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Réseau de surveillance volontaire des lacs (RSVL)

RSVL (Overview) (PDF, 571 kb)

RELAIS - Online Service (For existing RSVL lake monitoring participants)

Contact us (French)

Location  of participating lakes (French, PDF, 1.1 Mb)

Methods used to assess lake trophic status

Water quality results (French)

Folder (French, PDF, 293 kb)

Application to join the RSVL network (French)
(To add a new lake to the network only)


Together with its partners, the Réseau de surveillance volontaire des lacs pursues the following objectives:

  • Acquire data to determine the trophic level of a large number lakes and monitor their evolution over time;
  • Identify lakes showing signs of eutrophication and degradation;
  • Educate, increase awareness, support and inform lake associations and other participants;
  • Provide an overview of the state of Québec’s recreational lakes.

Sharing of responsibilities

Ministère’s RSVL team
Lake association or participating organization
  • Coordinates and supervises the Program
  • Supports lake association members
  • Analyzes the data and communicates the results
  • Develops supporting tools and documents
  • Teams with local partners to support lake association members
  • Collects water samples
  • Makes measurements and observations in the field using the provided protocols

For optimal results, participants who register a lake should commit to a long-term monitoring effort.


Monitoring activities

  • Water quality is monitored by:Photo : ABVLACS
    • measuring water transparency (Secchi disk depth);
    • collecting water samples for laboratory measurements of phosphorus, dissolved organic carbon and chlorophyll a. All water analyses are performed by the Ministère’s laboratory, the Centre d’expertise en analyse environnementale du Québec (CEAEQ).

Transparency measurements and water samples are taken at a station generally located in the deepest part of the lake. For a very large lake, more than one station may be needed.
  • In addition to water quality measurements procedures, participants are also provided with protocols to assess state of the riparian strip and littoral zone.

Water quality monitoring: What is involved?

Water transparency

  • Using a Secchi disk, water transparency should be measured every two weeks, from the beginning of June to the beginning of October, on an annual basis.

    Water transparency is an easy and inexpensive measure that can reveal long-term changes in water quality and the general state of the lake.

Water sampling

  • The basic water monitoring program was modified in 2010. The program now involves sampling for two or three consecutive years, in June, July and August. A pause of four years is taken before sampling resumes.

    For example, if the last sampling took place in 2010, sampling would resume in 2015 after a four-year break.

This monitoring plan is designed to achieve greater precision in estimating average concentrations of the water quality variables used to evaluate the lake’s trophic level.

The approach taken by the RSVL is to evaluate the precision obtained for each lake after a two-year monitoring period. Depending on the results, an optional third year of sampling may be suggested to the participants to improve precision. However, a participant may choose right from the start to sample for two or three consecutive years. After each additional year of sampling, precision of the mean concentration estimates will be recalculated. For lakes displaying a high variability, RSVL specialists could recommend that the number of samples taken annually be increased to improve precision.



In order to support the monitoring and protection of lakes, the Ministère will assume 75% of the fees associated with the RSVL (French, PDF, 417 Kb) for the next three years. Consequently, in 2021, the cost for performing laboratory analyses is $120 per station. In addition to the cost of analyzing three samples per station, the total includes accompanying documentation, delivery and taxes. In addition, $69 is added to the cost for the acquisition of a Secchi Disk for each new station added to the network. Prices are subject to change without prior notice.

No charges are incurred for years when participants only monitor water clarity.

The RSVL program is getting better with time

Analyses of the data collected since 2004 have revealed that in order to account for normal variations in water quality over the course of a summer and from year to year, the best monitoring strategy for the RSVL is to sample over several consecutive years. This allows obtaining enough data for average concentrations to be calculated with acceptable precision, while holding down the expense of laboratory analyses.

How many years of monitoring are required to obtain sufficient precision? This varies from lake to lake and from one water quality variable to another. Without being a stringent constraint, the total phosphorus parameter objective is to achieve a margin of error of within 20% of average value.


Protocols and support documents

English versions available upon request.


RELAIS - Online Service

RELAIS is an online service that allows RSVL participants to access their files, enter and/or change information and dialogue with RSVL managers at the Ministère.

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