Hudson Bayou Condition Report for 2021

Pass
Rating icon - Chlorophyll a Rating icon - Total Nitrogen Rating icon - Total Phosphorous Rating icon - Dissolved Oxygen Saturation

4 out of 4 indicators were rated as PASS.

All four indicators must pass for the creek to be rated as PASS.

Learn more about how this report is created

  • Size: 2,406 acres
  • Location: North Sarasota County
  • Discharges into: Sarasota Bay

For more information, please see: Sarasota Bay Water Quality Management Plan (2012)

View county-wide water quality trends »

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Hudson Bayou

Hudson Bayou
Visit the Hudson Bayou water resource page »

Water Chemistry Ratings | Freshwater Portion of the Creek

Creek Conditions Ratings are based on comparing nitrogen, phosphorus, chlorophyll and dissolved oxygen to water quality guidelines or regulations. Florida law defines a maximum allowable concentration of nitrogen, phosphorus, and chlorophyll a, and a minimum allowable concentration of dissolved oxygen in these streams. Learn more about these ratings and how they are calculated »

Data for the following WBIDs is averaged when compiling the data below:
  • 1953A
Chart Legend
  • Trend Line
  • Annual Mean
  • Threshold
Pass

Chlorophyll a

Score: Pass
Units: mg/L Year
2021		 Historical
period of record
High 0.0092 0.1568
Mean 0.0012 0.0012 0.01135948
Low 0.0004 0.0002
No. of Samples 24 549

Five-year Rolling Average

  • Annual Mean
Pass

Nitrogen, Total

Score: Pass
Units: mg/L Year
2021		 Historical
period of record
High 3.69 17.52
Mean 1.1142 0.892 0.95417284
Low 0.738 0.0018
No. of Samples 24 382

Five-year Rolling Average

  • Annual Mean
Pass

Phosphorus, Total

Score: Pass
Units: mg/L Year
2021		 Historical
period of record
High 0.99 4.05
Mean 0.3269 0.415 0.34052779
Low 0.127 0.047
No. of Samples 24 453

Five-year Rolling Average

  • Annual Mean
Pass

Dissolved Oxygen Saturation

Note: Low DO saturation also may be naturally influenced by inflows from nearby wetlands or groundwater sources.
Score: Pass
Units: percent (%) Year
2021		 Historical
period of record
High 489.00 489.00
Mean 60.24 52.9 33.7207
Low 18.00 1.1583
No. of Samples 24 459

Five-year Rolling Average

  • Annual Mean

BOD, Biochemical oxygen demand

Units: mg/l Year
2021		 Historical
period of record
High 3.68 13.10
Mean 1.16 1.03 1.44822
Low 1.00 0.50
No. of Samples 22 421

Five-year Rolling Average

  • Annual Mean

Color

Units: PCU Year
2021		 Historical
period of record
High 260.00 400.00
Mean 76.23 73.58 30.66575
Low 30.00 20.00
No. of Samples 24 526

Five-year Rolling Average

  • Annual Mean

Escherichia coli

Units: MPN/100ml Year
2021		 Historical
period of record
High 9804.00 24196.00
Mean 1409.88 1305.86 3011.6946
Low 181.00 41.00
No. of Samples 24 236

Five-year Rolling Average

  • Annual Mean

Nitrogen, Ammonia + Ammonium as N

Units: mg/L Year
2021		 Historical
period of record
High 0.589 0.65
Mean 0.06 0.05 0.10411913
Low 0.008 0.00
No. of Samples 24 477

Five-year Rolling Average

  • Annual Mean

Nitrogen, Kjeldahl

Units: mg/L Year
2021		 Historical
period of record
High 2.49 13.80
Mean 0.88 0.79 0.95424024
Low 0.517 0.00
No. of Samples 24 452

Five-year Rolling Average

  • Annual Mean

Nitrogen, Nitrite + Nitrate as N

Units: mg/L Year
2021		 Historical
period of record
High 1.20 3.72
Mean 0.18 0.12 0.27362668
Low 0.004 0.004
No. of Samples 24 452

Five-year Rolling Average

  • Annual Mean

pH

Units: None Year
2021		 Historical
period of record
High 7.75 758.00
Mean 7.39 7.46 32.30213
Low 6.96 6.20
No. of Samples 24 540

Five-year Rolling Average

  • Annual Mean

Salinity

Units: PSS Year
2021		 Historical
period of record
High 1.18 25.30
Mean 0.38 0.37 2.2839
Low 0.2029 0.04
No. of Samples 24 533

Five-year Rolling Average

  • Annual Mean

Specific conductance

Units: umho Year
2021		 Historical
period of record
High 2413.00 54000.00
Mean 788.65 887.52 10081.33477
Low 418.649 0.445
No. of Samples 24 455

Five-year Rolling Average

  • Annual Mean

Temperature, water

Units: deg F Year
2021		 Historical
period of record
High 185.7632 186.6636
Mean 168.76 81.02 30.95009
Low 150.7874 53.87
No. of Samples 24 456

Five-year Rolling Average

  • Annual Mean

Turbidity

Units: NTU Year
2021		 Historical
period of record
High 60.00
Mean 3.72 4.77177
Low 1.00
No. of Samples 0 324

Five-year Rolling Average

  • Annual Mean
Other Measures of Creek Health:

Water Chemistry Ratings | Tidal Portion of the Creek

Creek Conditions Ratings are based on comparing nitrogen, phosphorus, chlorophyll and dissolved oxygen to water quality guidelines or regulations. Florida law defines a maximum allowable concentration of chlorophyll a and a minimum allowable concentration of dissolved oxygen in these streams. Florida has no regulatory thresholds for nitrogen or phosphorus in tidal creeks so trends are used to rate the creeks. Learn more about these ratings and how they are calculated »

Data for the following WBIDs is averaged when compiling the data below:
  • 1951
  • 1953
Chart Legend
  • Trend Line
  • Annual Mean
  • Threshold

Chlorophyll a

Units: mg/L Year
2021		 Historical
period of record
High 0.1
Mean 0.0035 0.01085351
Low 0.0003
No. of Samples 0 108

Five-year Rolling Average

  • Annual Mean
×

Chlorophyll a

The rating for Chlorophyll a is determined by comparing the annual arithmetic mean of its sampled values to fixed target and threshold values. The annual arithmetic mean is shown in the graph at left, as compared to its established target and threshold values.

An arithmetic mean is used for Chlorophyll a for consistency with the Surface Water Quality Standards, Florida Administrative Code 62-302.532, Estuary-Specific Numeric Interpretations of the Narrative Nutrient Criterion.

Nitrogen, Total

We were unable to determine a trend for the data available.
Units: mg/L Year
2021		 Historical
period of record
High 1.9
Mean 0.8553 0.30219187
Low 0.34
No. of Samples 0 131

Five-year Rolling Average

  • Annual Mean
×

Nitrogen, Total

Phosphorus, Total

We were unable to determine a trend for the data available.
Units: mg/L Year
2021		 Historical
period of record
High 1.3
Mean 0.285 0.2334838
Low 0.05
No. of Samples 0 143

Five-year Rolling Average

  • Annual Mean
×

Phosphorus, Total

Dissolved Oxygen Saturation

Note: Low DO saturation also may be naturally influenced by inflows from nearby wetlands or groundwater sources
Units: percent (%) Year
2021		 Historical
period of record
High 128.7
Mean 44.99 26.00298
Low 0.70
No. of Samples 0 208

Five-year Rolling Average

  • Annual Mean
×

Dissolved Oxygen Saturation

BOD, Biochemical oxygen demand

Units: mg/l Year
2021		 Historical
period of record
High 5.4
Mean 1.87 1.08906
Low 0.50
No. of Samples 0 83

Five-year Rolling Average

  • Annual Mean

Color

Units: PCU Year
2021		 Historical
period of record
High 125.0
Mean 29.1 22.59603
Low 5.00
No. of Samples 0 206

Five-year Rolling Average

  • Annual Mean

Nitrogen, Ammonia + Ammonium as N

Units: mg/L Year
2021		 Historical
period of record
High 0.9
Mean 0.02 0.13400805
Low 0.00
No. of Samples 0 191

Five-year Rolling Average

  • Annual Mean

Nitrogen, Kjeldahl

Units: mg/L Year
2021		 Historical
period of record
High 1.9
Mean 0.73 0.30108917
Low 0.16
No. of Samples 0 189

Five-year Rolling Average

  • Annual Mean

Nitrogen, Nitrite + Nitrate as N

Units: mg/L Year
2021		 Historical
period of record
High 0.7
Mean 0.06 0.13489466
Low 0.00
No. of Samples 0 151

Five-year Rolling Average

  • Annual Mean

pH

Units: None Year
2021		 Historical
period of record
High 8.4
Mean 7.7 0.43838
Low 6.38
No. of Samples 0 210

Five-year Rolling Average

  • Annual Mean

Salinity

Units: PSS Year
2021		 Historical
period of record
High 34.7
Mean 19.12 9.4904
Low 0.35
No. of Samples 0 198

Five-year Rolling Average

  • Annual Mean

Specific conductance

Units: umho Year
2021		 Historical
period of record
High 53,000.0
Mean 35681.85 11577.84158
Low 46.582
No. of Samples 0 291

Five-year Rolling Average

  • Annual Mean

Temperature, water

Units: deg F Year
2021		 Historical
period of record
High 94.2
Mean 75.47 8.35351
Low 51.80
No. of Samples 0 216

Five-year Rolling Average

  • Annual Mean

Turbidity

Units: NTU Year
2021		 Historical
period of record
High 42.0
Mean 4.66 4.45724
Low 0.27
No. of Samples 0 205

Five-year Rolling Average

  • Annual Mean
Other Measures of Creek Health:

Oysters

Because they are immobile and will tolerate a fairly wide salinity range, eastern oysters (Crassostrea virginica) are valuable as an indicator of the relative health of aquatic ecosystems in the tidally-influenced portions of coastal creeks. Sarasota County has established an oyster monitoring program to track the location, types, and status of oyster reefs. Data from this monitoring program is shown below. Learn more about Oysters »

Loading oyster site map...
Most Recent Sarasota County Oyster Monitoring Program Data
Icon Site ID Year Dead Live Total % Live
1 HUD2 2021 50 147 197 74

Impervious Features

Hudson Bayou is located within the Sarasota Bay Watershed. View details about the Sarasota Bay Watershed »

Rain that falls on land that is in a natural state is absorbed and filtered by soils and vegetation as it makes it way into underground aquifers. However, in developed areas, "impervious surfaces" impede this process and contribute to polluted urban runoff entering surface waters. These surfaces include human infrastructure like roads, sidewalks, driveways and parking lots that are covered by impenetrable materials such as asphalt, concrete, brick and stone, as well as buildings and other permanent structures. Soils that have been disturbed and compacted by urban development are often impervious as well. Learn more about Impervious Features »

The Sarasota County Stormwater Environmental Utility (SEU) mapped impervious surfaces in the County in 2013. A map showing impervious surfaces can be viewed using the Water Atlas Map Viewer tool.

47% of the land area within the Hudson Bayou Basin is covered by impervious surfaces

Impervious Surface Coverage by Type

Land Use / Land Cover

Hudson Bayou is located within the Sarasota Bay Watershed. View details about the Sarasota Bay Watershed »

Land use within a creek's watershed has a major effect on its water quality. In general, less development means better water quality. Land Cover/Land Use classifications categorize land in terms of its observed physical surface characteristics (e.g. upland or wetland), and also reflect the types of activity that are taking place on it (agriculture, urban/built-up, utilities, etc.). Florida uses as its standard a set of statewide classifications which were developed by the Florida Department of Transportation. Learn more about Land Use and Land Cover »

Acreage and Percentage within each Land Use / Land Cover Category for Hudson Bayou Basin
Land Use Classification 1990 1995 1999 2005 2011 2014 2017 2020 Trend
Urban & Built-up 2,22492.4% 2,24493.3% 2,24393.2% 2,26093.9% 2,26093.9% 2,24993.5% 2,26093.9% 2,25993.9% Land Use Trend Sparkline
Upland Forests 160.7% 90.4% 90.4% 00% 00% 00% 00% 00% Land Use Trend Sparkline
Water 241% 251% 261.1% 261.1% 271.1% 271.1% 271.1% 271.1% Land Use Trend Sparkline
Wetlands 160.7% 130.5% 130.5% 100.4% 100.4% 100.4% 100.4% 100.4% Land Use Trend Sparkline
Transportation and Utilities 1265.2% 1154.8% 1154.8% 1094.6% 1094.6% 1205% 1094.5% 1104.6% Land Use Trend Sparkline
Land Use Chart