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

2 out of 4 primary indicators were rated as PASS.

"Primary" are nutrient related (Chl, N, P) and bacteria (B) parameters.

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

Greyed out values indicate no data for the report year.

  • Size: 473 acres
  • Location: Central Sarasota County
  • Discharges into: Little Sarasota Bay

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

View county-wide water quality trends »

Elligraw Bayou

Water Chemistry Ratings

Monitoring data is analyzed to determine stream health based on State water quality standards. Official determination of impairment or attainment of the water quality standards is performed by FDEP and is based on at least three years and up to seven and a half years of data. Information on approximately 17 different parameters are collected at stream sites, but only total nitrogen, total phosphorus, chlorophyll a, dissolved oxygen (percent saturation), and bacteria are assessed according to established water quality criteria mandated by the Clean Water Act. Additionally, the floral and faunal communities (SCI) are assessed at some sites to determine whether waters support a healthy aquatic community.

The "pass/fail" conditions presented here do not indicate impairment as determined by the official Florida Department of Environmental Protection Impaired Waters Rule assessment but, rather, give an indication of stream condition in a particular year in relation to the set regulatory numeric limits. Streams receive an annual "PASS" rating for each parameter if the mean value is below the regulatory value and a "FAIL" rating if the mean value exceeds the regulatory value. Not all water quality parameters have an established numeric criterion, so only some of the graphs below show the regulatory limit, represented by a horizontal red line.

Chart Legend
  • Monthly Average
  • Threshold
  • Annual Mean

The graphs here illustrate results over the past five years. Data from sites monitored within a single waterbody identification basin (WBID) are combined to determine water quality status for each WBID, and the annual geometric mean of sample results is indicated on the graph for the most recent year. The table to the left of the graph gives the annual and historic range of values for the indicator.

Click the graph to view a larger image and to download the full dataset.

Freshwater Portion of the Creek

Data for the following WBIDs is averaged when compiling the data below:
  • 1975E
Other Measures of Creek Health:

Tidal Portion of the Creek

Data for the following WBIDs is averaged when compiling the data below:
  • 1975
  • 1975F
Caution

Chlorophyll a

Score: Caution
Units: µg/l Year
2020
Historical
period of record
High 75.4 120.0
Mean 24.6042 15.8035 19.98094
Low 2.52 0.25
No. of Samples 12 304
  • Monthly Average
  • NNC 11.00 ug/l
  • Annual Mean
Pass

Nitrogen, Total

No trend was observed after performing a trend analysis.
Score: Pass
Units: mg/L Year
2020
Historical
period of record
High 1.8 4.2
Mean 1.4317 1.2785 0.43794344
Low 1.145 0.0022
No. of Samples 12 308
  • Monthly Average
  • Annual Mean
Caution

Phosphorus, Total

Trend analysis shows a weak increasing trend.
Score: Caution
Units: mg/L Year
2020
Historical
period of record
High 0.6 1.6
Mean 0.37 0.3569 0.19874877
Low 0.209 0.064
No. of Samples 12 352
  • Monthly Average
  • Annual Mean
Caution

Dissolved Oxygen Saturation

Note: Dissolved oxygen saturation percentages above the regulatory threshold meet established water quality targets.
Score: Caution
Units: percent (%) Year
2020
Historical
period of record
High 92.8 167.7
Mean 54.07 50.91 26.106
Low 34.90 2.10
No. of Samples 14 416
  • Monthly Average
  • NNC 56.00 percent (%)
  • Annual Mean

BOD, Biochemical oxygen demand

Units: mg/l Year
2020
Historical
period of record
High 5.6 14.8
Mean 2.45 2.24 1.81189
Low 1.00 0.50
No. of Samples 12 277
  • Monthly Average
  • Annual Mean

Color

Units: PCU Year
2020
Historical
period of record
High 130.0 220.0
Mean 89.06 69.21 23.81495
Low 60.00 20.00
No. of Samples 12 421
  • Monthly Average
  • Annual Mean

Enterococcus Group Bacteria

Units: MPN/100ml Year
2020
Historical
period of record
High 119.0 119.0
Mean 100.57 100.57 24.04163
Low 85.00 85.00
No. of Samples 2 2
  • Monthly Average
  • Annual Mean

Nitrogen, Ammonia + Ammonium as N

Units: mg/L Year
2020
Historical
period of record
High 0.2 0.7
Mean 0.02 0.02 0.09520005
Low 0.008 0.00
No. of Samples 12 419
  • Monthly Average
  • Annual Mean

Nitrogen, Kjeldahl

Units: mg/L Year
2020
Historical
period of record
High 1.8 4.2
Mean 1.4 1.24 0.43584213
Low 1.11 0.05
No. of Samples 12 403
  • Monthly Average
  • Annual Mean

Nitrogen, Nitrite + Nitrate as N

Units: mg/L Year
2020
Historical
period of record
High 0.2 0.5
Mean 0.02 0.02 0.0890826
Low 0.004 0.00
No. of Samples 12 358
  • Monthly Average
  • Annual Mean

pH

Units: None Year
2020
Historical
period of record
High 8.4 8.8
Mean 7.61 7.65 0.32715
Low 7.1243 6.33
No. of Samples 14 465
  • Monthly Average
  • Annual Mean

Salinity

Units: PSS Year
2020
Historical
period of record
High 0.6 31.0
Mean 0.42 0.71 5.75947
Low 0.2695 0.00
No. of Samples 16 412
  • Monthly Average
  • Annual Mean

Specific conductance

Units: µmho Year
2020
Historical
period of record
High 1,096.0 52,000.0
Mean 822.11 1517.25 10667.36406
Low 552.168 0.871
No. of Samples 14 488
  • Monthly Average
  • Annual Mean

Temperature, water

Units: °F Year
2020
Historical
period of record
High 65.3 93.2
Mean 65.21 73.64 8.71529
Low 65.12 47.408
No. of Samples 2 390
  • Monthly Average
  • Annual Mean

Turbidity

Units: NTU Year
2020
Historical
period of record
High 35.0
Mean 3.12 4.00228
Low 0.61
No. of Samples 0 369
  • Monthly 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

Impervious Features

Elligraw Bayou is located within the Little Sarasota Bay Watershed. View details about the Little 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.

31% of the land area within the Elligraw Bayou Basin is covered by impervious surfaces

Impervious Surface Coverage by Type

Land Use / Land Cover

Elligraw Bayou is located within the Little Sarasota Bay Watershed. View details about the Little 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 Elligraw Bayou Basin
Land Use Classification 1990 1995 1999 2005 2011 2014 2017 2020 2023 Trend
Urban & Built-up 41287.2% 40485.6% 40886.3% 40886.3% 40886.4% 39182.7% 40886.4% 40886.4% 41186.9% Land Use Trend Sparkline
Upland Forests 142.9% 143% 132.8% 132.8% 132.8% 163.3% 132.8% 132.8% 112.3% Land Use Trend Sparkline
Water 286% 336.9% 377.8% 347.1% 367.6% 367.6% 367.6% 367.6% 367.6% Land Use Trend Sparkline
Wetlands 102.2% 122.5% 51% 81.7% 51.1% 102.1% 51.1% 51.1% 51.1% Land Use Trend Sparkline
Transportation and Utilities 91.8% 102.1% 102.1% 102.1% 102.1% 204.2% 102.1% 102.1% 102.1% Land Use Trend Sparkline
Land Use Chart