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: 47,518 acres
  • Location: North and central Sarasota County, south Manatee County
  • Discharges into: Dona Bay

The hydrologic boundary of the Cow Pen Slough Basin is indeterminate in many areas due to the flat topography and undefined drainageways. Drainage from the basin is conveyed through 14 miles of improved channel. There are two operational flood control structures on the channel which were designed to provide grade control and water conservation. At present the Cow Pen Slough Basin is primarily rural in nature, with the majority of the land uses being classified as rangeland, crop and pastureland, orchards and groves, and upland forests. There are localized areas that are primarily urban in nature around Bee Ridge and north of Venice, with the majority being classified as residential. For basin details see: Cow Pen Slough Basin Master Plan (USDA Report, 1997)

Cow Pen Slough

Cow Pen Slough

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:
  • 1924
  • 1924B
  • 1987
  • 1994
  • 1996
  • 2004
Chart Legend
  • Trend Line
  • Annual Mean
  • Threshold
Pass

Chlorophyll a

Score: Pass
Units: mg/l Year
2013
Historical
period of record
High 0.0617 0.243
Mean 0.0092 0.0109 0.02144097
Low 0.0014 0.0006
No. of Samples 74 533

Five-year Rolling Average

  • Annual Mean
Pass

Nitrogen, Total

Score: Pass
Units: mg/l Year
2013
Historical
period of record
High 1.791 2.73
Mean 1.034 0.9744 0.44258065
Low 0.508 0.15
No. of Samples 24 343

Five-year Rolling Average

  • Annual Mean
Pass

Phosphorus, Total

Score: Pass
Units: mg/l Year
2013
Historical
period of record
High 0.356 1.19
Mean 0.1559 0.1782 0.16935593
Low 0.057 0.02
No. of Samples 72 583

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
2013
Historical
period of record
High 144.70 227.16
Mean 67.52 72.15 31.84271
Low 17.40 2.381
No. of Samples 68 805

Five-year Rolling Average

  • Annual Mean

BOD, Biochemical oxygen demand

Units: mg/l Year
2013
Historical
period of record
High 4.52 13.90
Mean 1.71 1.74 1.66367
Low 0.50 0.00
No. of Samples 72 541

Five-year Rolling Average

  • Annual Mean

Color

Units: PCU Year
2013
Historical
period of record
High 650.00
Mean 85.82 87.0036
Low 10.00
No. of Samples 0 274

Five-year Rolling Average

  • Annual Mean

Escherichia coli

Units: cfu/100ml Year
2013
Historical
period of record
High 230.00
Mean 117.47 120.20815
Low 60.00
No. of Samples 0 2

Five-year Rolling Average

  • Annual Mean

Nitrogen, Ammonia + Ammonium as N

Units: ug/l Year
2013
Historical
period of record
High 142.00 605.00
Mean 18.91 18.61 97.56985
Low 8.00 0.00
No. of Samples 72 680

Five-year Rolling Average

  • Annual Mean

Nitrogen, Kjeldahl

Units: ug/l Year
2013
Historical
period of record
High 1630.00 8400.00
Mean 996.13 987.25 491.42583
Low 502.00 0.00
No. of Samples 72 667

Five-year Rolling Average

  • Annual Mean

Nitrogen, Nitrite + Nitrate as N

Units: ug/l Year
2013
Historical
period of record
High 181.00 2210.00
Mean 17.94 19.62 100.24273
Low 4.00 0.00
No. of Samples 71 591

Five-year Rolling Average

  • Annual Mean

pH

Units: None Year
2013
Historical
period of record
High 8.17 11.50
Mean 7.49 7.59 0.36995
Low 6.87 5.80
No. of Samples 68 3,890

Five-year Rolling Average

  • Annual Mean

Salinity

Units: PSS Year
2013
Historical
period of record
High 31.02 76.50
Mean 1.12 22.95 15.40504
Low 0.12 0.00
No. of Samples 66 3,588

Five-year Rolling Average

  • Annual Mean

Specific conductance

Units: umho Year
2013
Historical
period of record
High 47567.00 59844.40
Mean 2056.37 18387.05 18275.99441
Low 253.00 0.512
No. of Samples 68 3,945

Five-year Rolling Average

  • Annual Mean

Temperature, water

Units: deg F Year
2013
Historical
period of record
High 86.846 92.426
Mean 78.3 77.49 7.62561
Low 65.75 47.372
No. of Samples 46 3,712

Five-year Rolling Average

  • Annual Mean

Turbidity

Units: NTU Year
2013
Historical
period of record
High 6.70 48.00
Mean 3.15 2.88 3.54741
Low 0.45 0.40
No. of Samples 71 734

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:
  • 1924A
Chart Legend
  • Trend Line
  • Annual Mean
  • Threshold

Chlorophyll a

Units: mg/l Year
2013
Historical
period of record
High 0.0
Mean 0.0104 0.00359453
Low 0.004
No. of Samples 0 15

Five-year Rolling Average

  • Annual Mean

Nitrogen, Total

Units: mg/l Year
2013
Historical
period of record
High 2.2
Mean 1.0972 0.44363338
Low 0.16
No. of Samples 0 42

Five-year Rolling Average

  • Annual Mean

Phosphorus, Total

Units: mg/l Year
2013
Historical
period of record
High 0.6
Mean 0.1913 0.11036761
Low 0.043
No. of Samples 0 39

Five-year Rolling Average

  • Annual Mean

Dissolved Oxygen Saturation

Units: percent (%) Year
2013
Historical
period of record
High 122.5
Mean 73.4 14.47615
Low 48.1012
No. of Samples 0 128

Five-year Rolling Average

  • Annual Mean

BOD, Biochemical oxygen demand

Units: mg/l Year
2013
Historical
period of record
High 1.2
Mean 1.2
Low 1.20
No. of Samples 0 1

Five-year Rolling Average

  • Annual Mean

Color

Units: PCU Year
2013
Historical
period of record
High 300.0
Mean 72.04 68.50301
Low 10.00
No. of Samples 0 112

Five-year Rolling Average

  • Annual Mean

Nitrogen, Ammonia + Ammonium as N

Units: ug/l Year
2013
Historical
period of record
High 203.0
Mean 1.03 27.60433
Low 0.00
No. of Samples 0 85

Five-year Rolling Average

  • Annual Mean

Nitrogen, Kjeldahl

Units: ug/l Year
2013
Historical
period of record
High 2,163.0
Mean 1032.51 432.97307
Low 50.00
No. of Samples 0 75

Five-year Rolling Average

  • Annual Mean

Nitrogen, Nitrite + Nitrate as N

Units: ug/l Year
2013
Historical
period of record
High 250.0
Mean 46.62 66.63103
Low 0.00
No. of Samples 0 45

Five-year Rolling Average

  • Annual Mean

Oysters

Units: Year
2013
Historical
period of record
High 635.0
Mean 63.46
Low 122.00
No. of Samples 502 3,908

Five-year Rolling Average

pH

Units: None Year
2013
Historical
period of record
High 8.6
Mean 7.61 0.3315
Low 6.80
No. of Samples 0 160

Five-year Rolling Average

  • Annual Mean

Salinity

Units: PSS Year
2013
Historical
period of record
High 33.5
Mean 11.59 8.63974
Low 0.00
No. of Samples 0 77

Five-year Rolling Average

  • Annual Mean

Specific conductance

Units: umho Year
2013
Historical
period of record
High 51,300.0
Mean 14280.55 15826.70882
Low 19.00
No. of Samples 0 335

Five-year Rolling Average

  • Annual Mean

Temperature, water

Units: deg F Year
2013
Historical
period of record
High 93.2
Mean 75.64 9.15805
Low 51.80
No. of Samples 0 248

Five-year Rolling Average

  • Annual Mean

Turbidity

Units: NTU Year
2013
Historical
period of record
High 11.0
Mean 2.82 1.74921
Low 1.00
No. of Samples 0 109

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 SKC4 2013 312 190 502 38

Impervious Features

Cow Pen Slough 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.

2% of the land area within the Cow Pen Slough Basin is covered by impervious surfaces

Impervious Surface Coverage by Type

Land Use / Land Cover

Cow Pen Slough 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 Cow Pen Slough Basin
Land Use Classification 1990 1995 1999 2005 2011 2014 Trend
Urban & Built-up 4,5089.5% 6,03812.7% 8,97518.9% 11,00123.2% 11,73024.7% 11,97425.2% Land Use Trend Sparkline
Agriculture 13,32028% 14,16429.8% 14,11229.7% 14,34730.2% 13,51228.4% 13,22727.8% Land Use Trend Sparkline
Rangeland 7,04114.8% 6,16813% 4,0568.5% 2,4485.2% 2,3074.9% 2,4885.2% Land Use Trend Sparkline
Upland Forests 11,44524.1% 10,05921.2% 8,50317.9% 7,48315.7% 7,37615.5% 7,30915.4% Land Use Trend Sparkline
Water 8161.7% 1,3452.8% 1,5213.2% 1,6443.5% 1,7633.7% 1,8173.8% Land Use Trend Sparkline
Wetlands 10,03521.1% 9,31019.6% 9,36719.7% 9,47119.9% 9,50720% 9,39719.8% Land Use Trend Sparkline
Barren Land 160% 50% 20% 490.1% 1100.2% 770.2% Land Use Trend Sparkline
Transportation and Utilities 3370.7% 4300.9% 9822.1% 1,0752.3% 1,2132.6% 1,2302.6% Land Use Trend Sparkline
Land Use Chart