HOW TO READ LAKE CONDITIONS UPDATES

This guide explains how to read the Lake Conditions Update, which summarizes current water quality data from SSEA’s three key lake monitoring station types: Inland Lakes – Nearshore, Inland Lakes – Deepest Point and Severn Sound Open Water. Each report offers a snapshot of conditions at specific sampling locations, with nearshore data based on averaged readings taken approximately one meter apart. An explanation of the update format is also provided to help interpret the information clearly and accurately.

For each lake monitoring station type, an example Lake Conditions Update figure is provided along with identification numbers which correspond with the text explanation. 

Nearshore areas
Inland lakes
Deepest Point
Inland Lakes
Open Water
Severn Sound

Inland Lake – Nearshore Areas

HOW TO READ THE 2025 LAKE CONDITIONS UPDATE (nearshore areas)

Each report provides a snapshot of current water conditions at specific sampling locations (nearshore areas). Three readings were taken approximately 1 metre apart nearshore, and the average was calculated and reported. 

Explanation Figure for LAKE CONDITIONS UPDATE - Nearshore Areas

Key components include:

  1.  SAMPLING LOCATION AND MAP: Shows the exact spot on the lake where data was collected.
  2. SAMPLING DATE: Indicates when the measurements were taken.
  3. WATER TEMPERATURE (°C): Measured in degrees Celsius using a multiparameter sonde (AquaTROLL 700), providing an indication of thermal conditions.
  4. WATER LEVEL: This is a relative assessment of the lake’s water level (high, normal, low) at the sampling location, based on multi-year observations by the SSEA field team. It is a qualitative and subjective evaluation, not a precise measurement.
  5. VISIBLE ALGAL BLOOM: Notes if visible algal blooms are present. For more information on algal blooms, see:  Fact Sheet All About Algae.
  6. BLUE-GREEN ALGAE LEVEL: Qualitatively described using a color-coded indicator (green for low levels, yellow for moderate, red for high levels) based on phycocyanin measurements (the pigment found in blue-green algae) taken with the AquaTROLL 700 sonde*. The current scale is 0–1 RFU for low, 1–10 RFU for moderate, and above 10 RFU for high levels. This scale is still under development and may be adjusted as more lake-specific data become available.
    Since last visit: Increased / Decreased / No change — this indicates how the phycocyanin concentration measured during the current sampling event compares to that recorded during the previous visit.
  7. ALGAE LEVEL: Qualitatively described using a color-coded indicator (green for low levels, yellow for moderate, red for high levels) based on chlorophyll a measurements, which indicate algae concentration (primarily green algae). Measurements are taken using the AquaTROLL 700 sonde*. The current scale is 0–1 RFU for low, 1–10 RFU for moderate, and above 10 RFU for high levels. This scale is still under development and may be adjusted as more lake-specific data become available.
    Since last visit: Increased / Decreased / No change — this indicates how the chlorophyll a concentration measured during the current sampling event compares to that recorded during the previous visit.
  8. OXYGEN LEVEL (mg/L): Determined by dissolved oxygen measurements in mg/L using the AquaTROLL 700 sonde*. Oxygen is essential for the survival of fish and other aquatic organisms. Values above 9 indicate good conditions (green), supporting healthy aquatic life. Levels between 9 and 5 indicate marginal conditions (yellow), which may cause stress to some species. Values from 5 to 2 represent moderate conditions (orange) where oxygen may be limiting for sensitive organisms. Levels below 2 (red) indicate poor conditions with critically low oxygen, which can lead to fish kills and other harmful effects on aquatic ecosystems.
    Since last visit: Increased / Decreased / No change — this indicates how the dissolved oxygen concentration measured during the current sampling event compares to that recorded during the previous visit.
  9. WATER CLOUDINESS: Evaluated based on turbidity measurements taken with the AquaTROLL 700 sonde. Turbidity represents how cloudy the water is due to suspended particles like algae, sediment, or organic matter. High turbidity can reduce light penetration, affecting aquatic plants and fish habitat. Values below 1 NTU indicate good conditions (green), 1–5 NTU marginal conditions (yellow), 5–25 NTU moderate conditions, and above 25 NTU (red) represent poor conditions.
    Since last visit: Increased / Decreased / No change — this indicates how turbidity measured during the current sampling event compares to that recorded during the previous visit.
  10.  GENERAL OBSERVATIONS: Any other relevant comments from the field team.
  11. Short explanation of some water quality parameters used for the report
  12. DISCLAIMER: Reminds readers that this data is for general reference and may change.
  13. Photo from the sampling location taken on the sampling date
    Note: All reported values, except for total depth and Secchi depth, are averages of profile measurements taken at 0.5 m and then at each additional meter of depth.
    *For detailed information on the AquaTROLL 700 multiparameter sonde used, including its specifications, please refer to this document: In-situ’s (Manufacturer) AquaTROLL Specificaion Sheet

Inland Lake – Deepest Points

HOW TO READ THE 2025 LAKE CONDITIONS UPDATE (deepest points of the lake)

Each report provides a snapshot of current water conditions at specific sampling locations. 

Explanation Figure for LAKE CONDITIONS UPDATE - Deepest Point

Key components include:

  1.  SAMPLING LOCATION AND MAP: Shows the exact spot on the lake where data was collected.
  2. SAMPLING DATE: Indicates when the measurements were taken.
  3. WATER TEMPERATURE (°C): Measured in degrees Celsius using a multiparameter sonde (AquaTROLL 700), providing an indication of thermal conditions.
  4. DEPTH (m): The total depth in meters at the sampling site.
  5. VISIBLE ALGAL BLOOM: Notes if visible algal blooms are present. For more information on algal blooms, see:  Fact Sheet All About Algae.
  6. BLUE-GREEN ALGAE LEVEL: Qualitatively described using a color-coded indicator (green for low levels, yellow for moderate, red for high levels) based on phycocyanin measurements (the pigment found in blue-green algae) taken with the AquaTROLL 700 sonde*. The current scale is 0–1 RFU for low, 1–10 RFU for moderate, and above 10 RFU for high levels. This scale is still under development and may be adjusted as more lake-specific data become available.
    Since last visit: Increased / Decreased / No change — this indicates how the phycocyanin concentration measured during the current sampling event compares to that recorded during the previous visit.
  7. ALGAE LEVEL: Qualitatively described using a color-coded indicator (green for low levels, yellow for moderate, red for high levels) based on chlorophyll a measurements, which indicate algae concentration (primarily green algae). Measurements are taken using the AquaTROLL 700 sonde*. The current scale is 0–1 RFU for low, 1–10 RFU for moderate, and above 10 RFU for high levels. This scale is still under development and may be adjusted as more lake-specific data become available.
    Since last visit: Increased / Decreased / No change — this indicates how the chlorophyll a concentration measured during the current sampling event compares to that recorded during the previous visit.
  8. OXYGEN LEVEL (mg/L): Determined by dissolved oxygen measurements in mg/L using the AquaTROLL 700 sonde*. Oxygen is essential for the survival of fish and other aquatic organisms. Values above 9 indicate good conditions (green), supporting healthy aquatic life. Levels between 9 and 5 indicate marginal conditions (yellow), which may cause stress to some species. Values from 5 to 2 represent moderate conditions (orange) where oxygen may be limiting for sensitive organisms. Levels below 2 (red) indicate poor conditions with critically low oxygen, which can lead to fish kills and other harmful effects on aquatic ecosystems.
    Since last visit: Increased / Decreased / No change — this indicates how the dissolved oxygen concentration measured during the current sampling event compares to that recorded during the previous visit.
  9. WATER CLOUDINESS: Evaluated based on turbidity measurements taken with the AquaTROLL 700 sonde. Turbidity represents how cloudy the water is due to suspended particles like algae, sediment, or organic matter. High turbidity can reduce light penetration, affecting aquatic plants and fish habitat. Values below 1 NTU indicate good conditions (green), 1–5 NTU marginal conditions (yellow), 5–25 NTU moderate conditions, and above 25 NTU (red) represent poor conditions.
    Since last visit: Increased / Decreased / No change — this indicates how turbidity measured during the current sampling event compares to that recorded during the previous visit.
  10.  GENERAL OBSERVATIONS: Any other relevant comments from the field team.
  11. Short explanation of some water quality parameters used for the report
  12. DISCLAIMER: Reminds readers that this data is for general reference and may change.
  13. Photo from the sampling location taken on the sampling date
    Note: All reported values, except for total depth and Secchi depth, are averages of profile measurements taken at 0.5 m and then at each additional meter of depth.
    *For detailed information on the AquaTROLL 700 multiparameter sonde used, including its specifications, please refer to this document: In-situ’s (Manufacturer) AquaTROLL Specificaion Sheet

FARLAIN LAKE WATER LEVEL UPDATE

HOW TO READ FARLAIN LAKE WATER LEVEL UPDATE

Each report provides a snapshot of current water level at Farlain Lake gauge.

How to Read the Farlain Lake Water Level Update

Key components include:

  1. Date: Indicates when the measurements were taken.
  2. Current water level: The water level measurements are reported as depths relative to the gauge. These values are not absolute elevations but are intended to illustrate the fluctuations and patterns observed in Farlain Lake’s water levels.
  3. Water level gauge location: Shows the exact spot on the lake where the gauge is located and where the data was collected.
  4. Photo: Image of water level gauge
  5. Indication of changes in water level since the last visit
  6. Plot showing changes in water level in 2025
  7. Indication of how the water level on the selected date compares to the monthly average (2019–2024). This shows whether the water level on a given date is higher, lower, or about the same as the typical level for that month, based on historical data from 2019 to 2024.
  8. Plot showing average annual water level (2019–2024). The chart shows the average water level in meters for each year, with the numbers above each bar indicating the exact value.
  9. Plot showing average monthly water level (2019–2024). The chart shows the average water level in meters for each month. The blue shaded area represents the typical range of water levels, the black vertical bars show how much levels can fluctuate each month, and the blue horizontal dashed line represents the overall average water level.
  10. Short explanation of annual and monthly plots
  11.  

Severn Sound – Open Water

HOW TO READ THE 2025 LAKE CONDITIONS UPDATE (deepest points of the lakes)

Each report provides a snapshot of current water conditions at specific sampling locations. 

Explanation Figure for LAKE CONDITIONS UPDATE - Severn Sound Open Water

Key components include:

  1.  SAMPLING LOCATION AND MAP: Shows the exact spot on the lake where data was collected.
  2. SAMPLING DATE: Indicates when the measurements were taken.
  3. WATER TEMPERATURE (°C): Measured in degrees Celsius using a multiparameter sonde (AquaTROLL 700), providing an indication of thermal conditions.
  4. DEPTH (m): The total depth in meters at the sampling site.
  5. WATER CLARITY: Assessed by the depth (m) at which a Secchi disk disappears when lowered into the water. Higher values indicate clearer water, with 1.2 meters usually considered the minimal acceptable depth unless the water is shallower. For more on Secchi disk methods, see this Secchi Disk Monitoring Guide.
  6. VISIBLE ALGAL BLOOM: Notes if visible algal blooms are present. For more information on algal blooms, see:  Fact Sheet All About Algae.
  7. BLUE-GREEN ALGAE LEVEL: Qualitatively described using a color-coded indicator (green for low levels, yellow for moderate, red for high levels) based on phycocyanin measurements (the pigment found in blue-green algae) taken with the AquaTROLL 700 sonde*. The current scale is 0–1 RFU for low, 1–10 RFU for moderate, and above 10 RFU for high levels. This scale is still under development and may be adjusted as more lake-specific data become available.
    Since last visit: Increased / Decreased / No change — this indicates how the phycocyanin concentration measured during the current sampling event compares to that recorded during the previous visit.
  8. ALGAE LEVEL: Qualitatively described using a color-coded indicator (green for low levels, yellow for moderate, red for high levels) based on chlorophyll a measurements, which indicate algae concentration (primarily green algae). Measurements are taken using the AquaTROLL 700 sonde*. The current scale is 0–1 RFU for low, 1–10 RFU for moderate, and above 10 RFU for high levels. This scale is still under development and may be adjusted as more lake-specific data become available.
    Since last visit: Increased / Decreased / No change — this indicates how the chlorophyll a concentration measured during the current sampling event compares to that recorded during the previous visit.


  9. OXYGEN LEVEL (mg/L): Determined by dissolved oxygen measurements in mg/L using the AquaTROLL 700 sonde*. Oxygen is essential for the survival of fish and other aquatic organisms. Values above 9 indicate good conditions (green), supporting healthy aquatic life. Levels between 9 and 5 indicate marginal conditions (yellow), which may cause stress to some species. Values from 5 to 2 represent moderate conditions (orange) where oxygen may be limiting for sensitive organisms. Levels below 2 (red) indicate poor conditions with critically low oxygen, which can lead to fish kills and other harmful effects on aquatic ecosystems.
    Since last visit: Increased / Decreased / No change — this indicates how the dissolved oxygen concentration measured during the current sampling event compares to that recorded during the previous visit.
  10. WATER CLOUDINESS: Evaluated based on turbidity measurements taken with the AquaTROLL 700 sonde. Turbidity represents how cloudy the water is due to suspended particles like algae, sediment, or organic matter. High turbidity can reduce light penetration, affecting aquatic plants and fish habitat. Values below 1 NTU indicate good conditions (green), 1–5 NTU marginal conditions (yellow), 5–25 NTU moderate conditions, and above 25 NTU (red) represent poor conditions.
    Since last visit: Increased / Decreased / No change — this indicates how turbidity measured during the current sampling event compares to that recorded during the previous visit.
  11.  GENERAL OBSERVATIONS: Any other relevant comments from the field team.
  12. Short explanation of some water quality parameters used for the report
  13. DISCLAIMER: Reminds readers that this data is for general reference and may change.
  14. Photo from the sampling location taken on the sampling date
    Note: All reported values, except for total depth and Secchi depth, are averages of profile measurements taken at 0.5 m and then at each additional meter of depth.
    *For detailed information on the AquaTROLL 700 multiparameter sonde used, including its specifications, please refer to this document: In-situ’s (Manufacturer) AquaTROLL Specificaion Sheet
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