Forked Creek Condition Report for 2019

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

3 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: 5,863 acres
  • Location: South Sarasota County
  • Discharges into: Lemon Bay

For more information, please see: Forked Creek Drainage Improvements, Preliminary Report Phase I (2000)

View county-wide water quality trends »

Dive Deeper!
Explore Water Quality Trends Watershed Management Plans Water Quality Contour Maps

Forked Creek

Forked Creek
Visit the Forked Creek 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 »

Chart Legend
  • Trend Line
  • Annual Mean
  • Threshold
Water quality data are not available for the freshwater portion of this creek.

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:
  • 2039
Chart Legend
  • Trend Line
  • Annual Mean
  • Threshold
Pass

Chlorophyll a

Score: Pass
Units: ug/l Year
2019		 Historical
period of record
High 19.8 221.0
Mean 7.8064 13.8249 29.04124
Low 1.47 0.25
No. of Samples 37 1,207

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
2019		 Historical
period of record
High 1.2 8.1
Mean 0.7523 1.0535 0.6626771
Low 0.487 0.00
No. of Samples 34 754

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
2019		 Historical
period of record
High 0.8 3.8
Mean 0.1984 0.2891 0.43836023
Low 0.095 0.004
No. of Samples 34 1,296

Five-year Rolling Average

  • Annual Mean
×

Phosphorus, Total

Caution

Dissolved Oxygen Saturation

Note: Low DO saturation also may be naturally influenced by inflows from nearby wetlands or groundwater sources
Score: Caution
Units: percent (%) Year
2019		 Historical
period of record
High 73.8 169.7
Mean 37.44 62.18 30.18884
Low 16.20 0.70
No. of Samples 22 1,027

Five-year Rolling Average

  • Annual Mean
×

Dissolved Oxygen Saturation

Other Measures of Creek Health:

BOD, Biochemical oxygen demand

Units: mg/l Year
2019		 Historical
period of record
High 2.7 16.7
Mean 1.6 2.21 2.01631
Low 1.00 0.50
No. of Samples 24 508

Five-year Rolling Average

  • Annual Mean

Color

Units: PCU Year
2019		 Historical
period of record
High 180.0 400.0
Mean 44.78 50.71 61.69989
Low 15.00 2.50
No. of Samples 34 1,425

Five-year Rolling Average

  • Annual Mean

Enterococcus Group Bacteria

Units: MPN/100ml Year
2019		 Historical
period of record
High 12,997.0 17,300.0
Mean 212.91 146.19 2071.21529
Low 10.00 10.00
No. of Samples 34 125

Five-year Rolling Average

  • Annual Mean

Nitrogen, Ammonia + Ammonium as N

Units: mg/L Year
2019		 Historical
period of record
High 1.5 1.5
Mean 0.13 0.02 0.13180992
Low 0.008 0.00
No. of Samples 24 685

Five-year Rolling Average

  • Annual Mean

Nitrogen, Kjeldahl

Units: mg/L Year
2019		 Historical
period of record
High 1.2 4.3
Mean 0.74 1.05 0.51937088
Low 0.468 0.05
No. of Samples 34 1,359

Five-year Rolling Average

  • Annual Mean

Nitrogen, Nitrite + Nitrate as N

Units: mg/L Year
2019		 Historical
period of record
High 0.1 0.9
Mean 0.02 0.02 0.04885166
Low 0.006 0.00
No. of Samples 34 1,078

Five-year Rolling Average

  • Annual Mean

pH

Units: None Year
2019		 Historical
period of record
High 7.8 9.3
Mean 7.43 7.73 0.42045
Low 7.12 4.90
No. of Samples 22 1,938

Five-year Rolling Average

  • Annual Mean

Salinity

Units: PSS Year
2019		 Historical
period of record
High 29.7 40.7
Mean 18.94 17.54 10.45834
Low 0.6082 0.00
No. of Samples 25 1,838

Five-year Rolling Average

  • Annual Mean

Specific conductance

Units: umho Year
2019		 Historical
period of record
High 45,500.0 55,192.0
Mean 27915.94 17975.88 16986.59434
Low 1208.44 0.941
No. of Samples 19 863

Five-year Rolling Average

  • Annual Mean

Temperature, water

Units: deg F Year
2019		 Historical
period of record
High 90.3 93.9
Mean 79.4 76.37 8.4327
Low 66.4623 50.00
No. of Samples 22 1,574

Five-year Rolling Average

  • Annual Mean

Turbidity

Units: NTU Year
2019		 Historical
period of record
High 60.0 402.0
Mean 4.02 3.29 15.06269
Low 1.60 0.10
No. of Samples 10 1,668

Five-year Rolling Average

  • Annual Mean

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 »

Most Recent Sarasota County Oyster Monitoring Program Data
Icon Site ID Year Dead Live Total % Live
1 FRK1 2016 12 55 67 82
2 FRK1A 2013 96 76 172 44
3 FRK2 2016 31 213 244 87

Impervious Features

Forked Creek is located within the Lemon Bay Watershed. View details about the Lemon 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.

7% of the land area within the Forked Creek Basin is covered by impervious surfaces

Impervious Surface Coverage by Type

Land Use / Land Cover

Forked Creek is located within the Lemon Bay Watershed. View details about the Lemon 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 Forked Creek Basin
Land Use Classification 1990 1995 1999 2005 2011 2014 2017 2020 Trend
Urban & Built-up 1,39423.8% 1,57026.8% 1,88832.2% 1,85931.7% 2,15436.7% 2,15436.7% 2,39340.8% 2,41841.3% Land Use Trend Sparkline
Agriculture 1,05518% 1,08118.4% 1,06418.2% 98816.8% 61910.6% 61910.6% 5339.1% 5138.7% Land Use Trend Sparkline
Rangeland 2324% 68811.7% 3956.7% 5529.4% 72612.4% 72612.4% 58710% 5158.8% Land Use Trend Sparkline
Upland Forests 2,05935.1% 1,32222.5% 1,31322.4% 1,18720.3% 1,03117.6% 1,03117.6% 98216.7% 93515.9% Land Use Trend Sparkline
Water 1392.4% 3906.7% 2374% 2293.9% 2764.7% 2764.7% 3185.4% 3756.4% Land Use Trend Sparkline
Wetlands 90515.4% 74312.7% 90415.4% 94416.1% 94816.2% 94816.2% 94316.1% 93916% Land Use Trend Sparkline
Barren Land 10% 00% 00% 00% 00% 00% 00% 60.1% Land Use Trend Sparkline
Transportation and Utilities 781.3% 681.2% 611% 1031.8% 1071.8% 1071.8% 1081.8% 1612.8% Land Use Trend Sparkline
Land Use Chart