Indicators

Nutrients

Total Nitrogen - Discrete

Scatter plot of monthly average total nitrogen over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only nitrogen values obtained from laboratory analyses (triangles) are included in the plot.
Scatter plot of monthly average total nitrogen over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only nitrogen values obtained from laboratory analyses (triangles) are included in the plot.
Seasonal Kendall-Tau Results for - Total Nitrogen
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median Result Value Tau Sen Intercept Sen Slope P
Lab No significant trend 1022 27 1997 - 2025 0.39995 0.02537 0.36784 0.00117 0.6032

Total nitrogen showed no detectable trend between 1997 and 2025.

Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

Total Phosphorus - Discrete

Scatter plot of monthly average total phosphorus over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only phosphorus values obtained from laboratory analyses (triangles) are included in the plot.
Scatter plot of monthly average total phosphorus over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only phosphorus values obtained from laboratory analyses (triangles) are included in the plot.
Seasonal Kendall-Tau Results for - Total Phosphorus
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median Result Value Tau Sen Intercept Sen Slope P
Lab No significant trend 1560 27 1997 - 2025 0.067 0.02256 0.0589 0.00017 0.5539

Total phosphorus showed no detectable trend between 1997 and 2025.

Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

Water Quality

Dissolved Oxygen - Discrete

Scatter plot of monthly average dissolved oxygen over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only dissolved oxygen values measured in the field (circles) are included in the plot.
Scatter plot of monthly average dissolved oxygen over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only dissolved oxygen values measured in the field (circles) are included in the plot.
Seasonal Kendall-Tau Results for - Dissolved Oxygen
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median Result Value Tau Sen Intercept Sen Slope P
Field Significantly decreasing trend 22657 30 1995 - 2025 6.8 -0.26925 7.31692 -0.03686 0

Monthly average dissolved oxygen decreased by 0.04 mg/L per year.

Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

Dissolved Oxygen - Continuous

Scatter plot of monthly average dissolved oxygen over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Scatter plot of monthly average dissolved oxygen over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Seasonal Kendall-Tau Results - Dissolved Oxygen
Program Location Statistical Trend Sample Count Years with Data Period of Record Median Result Value Tau Sen Intercept Sen Slope P
02231291 Insufficient data to calculate trend 689 3 2014 - 2016 5.70 - - - -
NECI Insufficient data to calculate trend 54461 3 2023 - 2025 6.20 - - - -
NEHM Insufficient data to calculate trend 85227 4 2022 - 2025 5.90 - - - -
NEKD No significant trend 110958 8 2004 - 2011 6.40 -0.04 6.59 -0.02 0.5607
NCBNRCM No significant trend 35477 5 2015 - 2019 5.79 0.05 5.78 0.01 0.797
NENR Insufficient data to calculate trend 31438 3 2009 - 2011 5.80 - - - -
NELC Significantly decreasing trend 95860 7 2005 - 2011 5.60 -0.34 5.93 -0.11 0.0014
NCB19020038 No significant trend 34476 5 2015 - 2019 6.16 -0.03 6.23 -0.03 0.6108
NCBARD16 Insufficient data to calculate trend 7417 2 2015 - 2016 5.08 - - - -

At one program location, monthly average dissolved oxygen decreased by 0.11 mg/L per year. No detectable change in monthly average dissolved oxygen was observed at three locations. There was insufficient data to fit a model for five locations.

Map showing location of dissolved oxygen continuous water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of dissolved oxygen continuous water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

Dissolved Oxygen Saturation - Discrete

Scatter plot of monthly average dissolved oxygen saturation over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only dissolved oxygen saturation values measured in the field (circles) are included in the plot.
Scatter plot of monthly average dissolved oxygen saturation over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only dissolved oxygen saturation values measured in the field (circles) are included in the plot.
Seasonal Kendall-Tau Results for - Dissolved Oxygen Saturation
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median Result Value Tau Sen Intercept Sen Slope P
Field No significant trend 1431 20 2000 - 2025 88 -0.07498 87.98412 -0.08082 0.1877

Dissolved oxygen saturation showed no detectable trend between 2000 and 2025.

Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

Dissolved Oxygen Saturation - Continuous

Scatter plot of monthly average dissolved oxygen saturation over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Scatter plot of monthly average dissolved oxygen saturation over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Seasonal Kendall-Tau Results - Dissolved Oxygen Saturation
Program Location Statistical Trend Sample Count Years with Data Period of Record Median Result Value Tau Sen Intercept Sen Slope P
NEHM Insufficient data to calculate trend 85226 4 2022 - 2025 74.60 - - - -
NECI Insufficient data to calculate trend 54808 3 2023 - 2025 82.40 - - - -
NEKD No significant trend 110983 8 2004 - 2011 89.10 0 87.49 -0.04 0.9338
NENR Insufficient data to calculate trend 31438 3 2009 - 2011 73.20 - - - -
NELC Significantly decreasing trend 95868 7 2005 - 2011 77.90 -0.27 78.93 -1.6 0.0111
NCBNRCM No significant trend 35240 5 2015 - 2019 82.06 -0.05 81.1 -0.14 0.797
NCB19020038 No significant trend 34438 5 2015 - 2019 87.06 -0.16 86.02 -0.6 0.1268
NCBARD16 Insufficient data to calculate trend 7417 2 2015 - 2016 74.44 - - - -

At one program location, monthly average dissolved oxygen saturation decreased by 1.60% per year. No detectable change in monthly average dissolved oxygen saturation was observed at three locations. There was insufficient data to fit a model for four locations.

Map showing location of dissolved oxygen saturation continuous water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of dissolved oxygen saturation continuous water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

Salinity - Discrete

Scatter plot of monthly average salinity over time. If the time series included ten or more years of discrete observations, significant (blue) or non-significant (magenta) trend lines are also shown. Discrete salinity values derived from grab samples analyzed in the field (circles) or the laboratory (triangles) are both included in the plot.
Scatter plot of monthly average salinity over time. If the time series included ten or more years of discrete observations, significant (blue) or non-significant (magenta) trend lines are also shown. Discrete salinity values derived from grab samples analyzed in the field (circles) or the laboratory (triangles) are both included in the plot.
Seasonal Kendall-Tau Results for - Salinity
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median Result Value Tau Sen Intercept Sen Slope P
All No significant trend 22769 30 1980 - 2025 30.5 -0.0506 29.81164 -0.04807 0.1992

Salinity showed no detectable trend between 1980 and 2025.

Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

Salinity - Continuous

Scatter plot of monthly average salinity over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Scatter plot of monthly average salinity over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Seasonal Kendall-Tau Results - Salinity
Program Location Statistical Trend Sample Count Years with Data Period of Record Median Result Value Tau Sen Intercept Sen Slope P
NEHM Insufficient data to calculate trend 88721 4 2022 - 2025 14.40 - - - -
NEKD Significantly increasing trend 118328 8 2004 - 2011 33.20 0.31 30.29 0.52 6e-04
NECI Insufficient data to calculate trend 54462 3 2023 - 2025 29.60 - - - -
NCB19020038 No significant trend 34438 5 2015 - 2019 31.75 -0.06 31.07 -0.11 1
NCBNRCM No significant trend 35411 5 2015 - 2019 30.29 -0.12 30.26 -0.39 0.5483
NENR Insufficient data to calculate trend 31438 3 2009 - 2011 12.40 - - - -
NELC No significant trend 100339 7 2005 - 2011 27.90 0.09 25.3 0.53 0.4397
NCBARD16 Insufficient data to calculate trend 7418 2 2015 - 2016 30.07 - - - -

At one program location, monthly average salinity increased by 0.52 ppt per year. No detectable change in monthly average salinity was observed at three locations. There was insufficient data to fit a model for four locations.

Map showing location of salinity continuous water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of salinity continuous water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

Water Temperature - Discrete

Scatter plot of monthly average water temperature over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only water temperature measurements taken in the field (circles) are included in the plot.
Scatter plot of monthly average water temperature over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only water temperature measurements taken in the field (circles) are included in the plot.
Seasonal Kendall-Tau Results for - Water Temperature
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median Result Value Tau Sen Intercept Sen Slope P
Field Significantly increasing trend 22815 30 1995 - 2025 23 0.12992 22.10918 0.03485 0.0013

Monthly average water temperature increased by 0.03°C per year.

Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

Water Temperature - Continuous

Scatter plot of monthly average water temperature over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Scatter plot of monthly average water temperature over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Seasonal Kendall-Tau Results - Water Temperature
Program Location Statistical Trend Sample Count Years with Data Period of Record Median Result Value Tau Sen Intercept Sen Slope P
02231291 Insufficient data to calculate trend 710 3 2014 - 2016 23.50 - - - -
NEKD No significant trend 118328 8 2004 - 2011 22.10 -0.04 21.88 -0.01 0.8057
NECI Insufficient data to calculate trend 54825 3 2023 - 2025 21.00 - - - -
NEHM Insufficient data to calculate trend 89130 4 2022 - 2025 22.80 - - - -
NCB19020038 No significant trend 34483 5 2015 - 2019 24.78 -0.03 23.32 -0.01 1
NENR Insufficient data to calculate trend 31438 3 2009 - 2011 22.00 - - - -
NELC No significant trend 100343 7 2005 - 2011 22.70 0.05 22.26 0.04 0.7405
NCBNRCM No significant trend 35817 5 2015 - 2019 24.03 0.07 23.26 0.05 0.6681
NCBARD16 Insufficient data to calculate trend 7419 2 2015 - 2016 25.08 - - - -

No detectable change in monthly average water temperature was observed at four locations. There was insufficient data to fit a model for five locations.

Map showing location of water temperature continuous water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of water temperature continuous water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

pH - Discrete

Scatter plot of monthly average pH over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only pH values measured in the field (circles) are included in the plot.
Scatter plot of monthly average pH over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only pH values measured in the field (circles) are included in the plot.
Seasonal Kendall-Tau Results for - pH
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median Result Value Tau Sen Intercept Sen Slope P
Field Significantly decreasing trend 22580 30 1995 - 2025 7.6 -0.14862 7.74068 -0.00518 2e-04

Monthly average pH decreased by 0.01 pH units per year.

Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

pH - Continuous

Scatter plot of monthly average pH over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Scatter plot of monthly average pH over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Seasonal Kendall-Tau Results - pH
Program Location Statistical Trend Sample Count Years with Data Period of Record Median Result Value Tau Sen Intercept Sen Slope P
NECI Insufficient data to calculate trend 52513 3 2023 - 2025 7.70 - - - -
NEHM Insufficient data to calculate trend 87193 4 2022 - 2025 7.10 - - - -
NEKD Significantly increasing trend 113471 8 2004 - 2011 7.90 0.19 7.87 0.01 0.0491
NENR Insufficient data to calculate trend 31438 3 2009 - 2011 7.10 - - - -
NCB19020038 No significant trend 34405 5 2015 - 2019 7.88 -0.01 7.85 0 1
NELC No significant trend 96488 7 2005 - 2011 7.50 0.02 7.51 0 0.9121
NCBNRCM No significant trend 35819 5 2015 - 2019 7.72 -0.01 7.69 0 0.9317
NCBARD16 Insufficient data to calculate trend 6952 2 2015 - 2016 7.66 - - - -

At one program location, monthly average pH increased by 0.01 pH units per year. No detectable change in monthly average pH was observed at three locations. There was insufficient data to fit a model for four locations.

Map showing location of ph continuous water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of ph continuous water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

Water Clarity

Turbidity - Discrete

Scatter plot of monthly average turbidity over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only turbidity values measured in the laboratory (triangles) are included in the plot.
Scatter plot of monthly average turbidity over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only turbidity values measured in the laboratory (triangles) are included in the plot.
Seasonal Kendall-Tau Results for - Turbidity
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median Result Value Tau Sen Intercept Sen Slope P
Lab Significantly increasing trend 1042 27 1997 - 2025 7.1 0.17743 4.03799 0.136 1e-04

Monthly average turbidity increased by 0.14 NTU per year, indicating a decrease in water clarity.

Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

Turbidity - Continuous

Scatter plot of monthly average turbidity over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Scatter plot of monthly average turbidity over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Seasonal Kendall-Tau Results - Turbidity
Program Location Statistical Trend Sample Count Years with Data Period of Record Median Result Value Tau Sen Intercept Sen Slope P
NEHM Insufficient data to calculate trend 83369 4 2022 - 2025 12.00 - - - -
NECI Insufficient data to calculate trend 53689 3 2023 - 2025 14.00 - - - -
NEKD No significant trend 114181 8 2004 - 2011 4.00 0.02 6.06 0.05 0.8697
NCBNRCM No significant trend 34696 5 2015 - 2019 8.64 -0.1 10.09 -0.14 0.6001
NCB19020038 No significant trend 31407 5 2015 - 2019 5.77 -0.01 6.79 0.12 0.7876
NENR Insufficient data to calculate trend 31087 3 2009 - 2011 21.00 - - - -
NELC No significant trend 96153 7 2005 - 2011 15.00 0.16 15.18 0.64 0.1513
NCBARD16 Insufficient data to calculate trend 7385 2 2015 - 2016 12.89 - - - -

No detectable change in monthly average turbidity was observed at four locations. There was insufficient data to fit a model for four locations.

Map showing location of turbidity continuous water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of turbidity continuous water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

Total Suspended Solids - Discrete

Scatter plot of monthly average total suspended solids (TSS) over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only TSS values obtained from laboratory analyses (triangles) are included in the plot.
Scatter plot of monthly average total suspended solids (TSS) over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only TSS values obtained from laboratory analyses (triangles) are included in the plot.
Seasonal Kendall-Tau Results for - Total Suspended Solids
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median Result Value Tau Sen Intercept Sen Slope P
Lab No significant trend 880 26 1997 - 2025 18 0.06226 17.36568 0.14902 0.1986

Total suspended solids showed no detectable trend between 1997 and 2025.

Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

Chlorophyll a, Uncorrected for Pheophytin - Discrete

Scatter plot of monthly average levels of chlorophyll a, uncorrected for pheophytin, over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only laboratory-analyzed chlorophyll a (triangles) is included in the plot.
Scatter plot of monthly average levels of chlorophyll a, uncorrected for pheophytin, over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only laboratory-analyzed chlorophyll a (triangles) is included in the plot.
Seasonal Kendall-Tau Results for - Chlorophyll a, Uncorrected for Pheophytin
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median Result Value Tau Sen Intercept Sen Slope P
Lab No significant trend 379 14 2004 - 2025 6.8 -0.10066 9.16876 -0.05456 0.6

Chlorophyll a, uncorrected for pheophytin, showed no detectable trend between 2004 and 2025.

Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

Chlorophyll a, Corrected for Pheophytin - Discrete

Scatter plot of monthly average levels of chlorophyll a, corrected for pheophytin, over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only laboratory-analyzed chlorophyll a (triangles) is included in the plot.
Scatter plot of monthly average levels of chlorophyll a, corrected for pheophytin, over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only laboratory-analyzed chlorophyll a (triangles) is included in the plot.
Seasonal Kendall-Tau Results for - Chlorophyll a, Corrected for Pheophytin
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median Result Value Tau Sen Intercept Sen Slope P
Lab Significantly increasing trend 699 19 2001 - 2025 5.7 0.13021 4.13929 0.10608 0.0473

Monthly average chlorophyll a, corrected for pheophytin, increased by 0.11 µg/L per year, indicating a decrease in water clarity.

Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

Secchi Depth - Discrete

Scatter plot of monthly average Secchi depth over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Secchi depth is only measured in the field (circles).
Scatter plot of monthly average Secchi depth over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Secchi depth is only measured in the field (circles).
Seasonal Kendall-Tau Results for - Secchi Depth
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median Result Value Tau Sen Intercept Sen Slope P
Field Significantly increasing trend 20402 26 2000 - 2025 -0.7 0.11221 -0.79285 0.00317 0.0085

Monthly average Secchi depth became shallower by less than 0.01 m per year, indicating a decrease in water clarity.

Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

Colored Dissolved Organic Matter - Discrete

Scatter plot of monthly average colored dissolved organic matter (CDOM) over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only laboratory-analyzed CDOM (triangles) is included in the plot.
Scatter plot of monthly average colored dissolved organic matter (CDOM) over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only laboratory-analyzed CDOM (triangles) is included in the plot.
Seasonal Kendall-Tau Results for - Colored Dissolved Organic Matter
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median Result Value Tau Sen Intercept Sen Slope P
Lab Insufficient data to calculate trend 498 6 2020 - 2025 27.0821 - - - -

There was insufficient data to fit a model for colored dissolved organic matter.

Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Nassau River-St. Johns River Marshes Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.