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20030157 (St. Johns River)
Basin Characterization
16,854.959 km²
Location: latitude 29°58’49.236”, longitude 81°37’15.348”, GPS datum—WGS-1984 Station 20030157 is located on the St. Johns River at the Shands Bridge on State Road 16.
Point Sources: There are no wastewater treatment facilities within a five-mile radius or within the drainage basin of this water quality site.
This site is located on the St. Johns River where State Road 16 crosses the river, just southeast of the city of Green Cove Springs in northeast Florida. There are several public boat ramps in the area for access to the river. The St. Johns River offers many opportunities for the public to enjoy. Whether you are in to fishing, boating, water skiing, or observing nature, you can find it on the St. Johns.
Wildlife is abundant throughout the reaches of the river and gives photographers many chances for sensational photos. The Bayard Conservation Area is located on the western shore of the river and covers over 10,300 acres and provides many recreational activities for the outhoors enthusiast.
The local area of this part of the St. Johns River has a mixture of commercial and private properties. There is a large boat works to the northwest of the sampling site, while the eastern shore has a smattering of private residences. Much of the shoreline is undeveloped due to the presence of wetlands.
Quick Links
All of the maps and charts shown below were created using a customized GIS data summary tool, with the watershed generated by Arc Hydro for this monitoring station. More information about Arc Hydro can be found by clicking on the tab “About Arc Hydro,” which includes a link to SWQM Arc Hydro Development. From that page, a description of the customized GIS data summary tool can be accessed.
Spatial Data Summaries
Download Spatial Data Summaries as an Excel file 
2000 population density
Population data is collected by the Census Bureau every 10 years and is used to show the distribution of population in a number of ways. Population density has a direct impact on land use, which effects water quality in areas around or near water bodies. This map displays the 2000 population density per square kilometer within this surface water catchment. The legend shows the area for each class in square kilometers and the percentage of area in descending order. More complete metadata can be found by clicking on the metadata link for the 2000 population density.
General land use 2000
Land use, which is usually derived from aerial photography by photo interpreters, shows the distribution of land and how it is used. Land use affects the water quality of water bodies through water runoff within a surface water catchment. This map displays the distribution of eight categories of general land use within this surface water catchment. The legend shows the area for each category in square kilometers and the percentage of area in descending order. More complete metadata can be found by clicking on the metadata link for general land use 2000.
Geology
The geology of the state of Florida was delineated by the Florida Geological Survey. Water quality is impacted by the underlying geology of streams and lakes. This map displays the underlying geological formations within this surface water catchment. The legend shows the area for each type of formation in square kilometers and the percentage of area in descending order. More complete metadata can be found by clicking on the metadata link for geology.
Physiographic divisions
Physiography describes the earth’s exterior physical features. These are divided into general groups and then subgroups containing features such as uplands, hills, ridges, plains, valleys, karst, etc. Water quality is affected through water runoff by physiography. This map displays the more detailed physiographic subdistricts within this surface water catchment. The legend shows the area for each subdistrict in square kilometers and the percentage of area in descending order. More complete metadata can be found by clicking on the metadata link for physiographic divisions.
2004 rainfall
Rainfall data comes from radar imaging as well as rainfall gauge surveys. Rainfall affects water quality through runoff within the surface water drainage basins. This map displays the total daily rainfall in inches for each pixel for 2004 within each surface water catchment. The legend shows the area for each rainfall range in square kilometers and the percentage of area in descending order. More complete metadata can be found by clicking on the metadata link for 2004 rainfall.
SJRWMD and other public lands
The St. Johns River Water Management District (SJRWMD) purchases lands that are in environmentally sensitive areas to protect the water resources on, beneath or adjoining the property. Water quality is affected in water bodies adjacent to these protected lands. This map displays the lands owned, jointly owned, being considered for purchase, or lands through which SJRWMD has an easement. The legend shows the area of these lands in square kilometers and the percentage of area in descending order. More complete metadata can be found by clicking on the metadata link for SJRWMD and public lands.
Soils drainage
Soils drainage characteristics can also impact surface water runoff, a source of nonpoint pollution for adjacent water bodies, which effects water quality. This map displays water bodies and soil drainage characteristics. The legend shows the area of these soils in square kilometers and the percentage of area in descending order. More complete metadata can be found by clicking on the metadata link for soils drainage.
5-foot elevation-DEM
Land elevation influences rainfall runoff, which effects the surface water quality, as water moves through the landscape to the rivers, streams, and lakes. This map with accompanying legend displays the maximum (MAX), minimum (MIN), range, standard deviation (STD) and mean of 5-foot elevations within the surface water drainage area (watershed). More complete metadata can be found by clicking on the metadata link for 5-foot elevation-DEM (Digital Elevation Model).
Recharge 1995
In some areas of SJRWMD, the Floridan aquifer is at or near land surface and is vulnerable to pollutants that threaten our drinking water supply. It is especially important to preserve surface water quality in these areas. This map displays recharge to the Floridan aquifer in inches per year (in/yr) within this surface water drainage catchment. Discharge, where the potentiometric surface is greater than the land surface elevation, is also shown. The area for each class is shown in square kilometers and the percentage of area in descending order. More complete metadata can be found by clicking on the metadata link for recharge 1995.
Arc Hydro model
The map below contains selected features from the St. Johns River Water Management District (SJRWMD) Arc Hydro geodatabase. The introduction of the SJRWMD Arc Hydro geodatabase made the creation of these fact pages possible, by providing improved geographic information system (GIS) data that has been combined into a GIS network. This hydrologically based network does for water resources what the commonly used mapping Web sites (such as MapBlast, MapQuest and GoogleMaps) have done for travel planning, except that instead of interstates, highways and roads, this hydrologic network shows streams, rivers, lakes and wetlands. Similar to transportation mapping sites, information about water resources has been related, or linked, to the GIS network and can be easily accessed. The legend to the right of the map includes the Arc Hydro network, Arc Hydro Polygon Feature Classes and HydroPoints. The features included in the Arc Hydro Network exist to establish relationships based on surface water flow. The lines (HydroEdges) may represent streams or rivers, which are commonly displayed as lines on maps. The lines may also represent, in a “shorthand” way, the concept of surface water flow through a lake or a wetland, which are not routinely displayed as lines. The features in the Arc Hydro Polygon Feature Classes and HydroPoints represent some of the water resources information that has been linked to the Arc Hydro GIS network. HDS refers to the District’s Hydrologic Data Services program and NWIS refers to the National Water Information System, which is part of the United States Geological Survey (USGS). See Technical Background for a more detailed explanation of the SJRWMD Arc Hydro technology and its features.
Clicking on the Methodology tab will direct you to information about how water quality samples were collected, analyzed, and summarized for this fact page. To access the most recent SJRWMD Surface Water Quality Status and Trends report, click here.
Water Quality
Download Water Quality Data as an Excel file
The St. Johns River is sampled near the State Road (SR) 16 bridge, also known as the Shands Bridge. The site is sampled monthly, under contract with FDEP. The St. Johns River at SR 16 is considered to be more estuarine than riverine, due to tidal influence. The river is about 5.4 meters deep at the site, with a typical temperature range. Conductivity and major ion concentrations are lower than typically found in estuaries, but are high enough to result in hard water at the site. The median dissolved oxygen concentration is above the FDEP standard for Class 3 surface waters. The water is moderately buffered and slightly alkaline. When compared to other estuarine sites, total suspended solids, chlorophyll, and coliforms concentrations are lower than typically found. Total organic carbon, total nitrogen, and total phosphorus are elevated. However, Secchi depth is low. The river at this site has poor water quality, according to the trophic state index.
| Analytes | Data Yrs | n Data | Min | Q1 | Median | Q3 | Max | Range |
|---|---|---|---|---|---|---|---|---|
| water temperature (degrees C) | 7 | 75 | 7.60 | 17.91 | 23.00 | 28.50 | 32.20 | mid |
| Secchi disc transparency (meters) | 7 | 74 | 0.20 | 0.60 | 0.65 | 0.85 | 1.40 | low |
| specific conductance field (uhmhos/cm@25°C) | 7 | 75 | 479.00 | 725.00 | 882.00 | 1243.00 | 10240.00 | low |
| sampling station depth (meters) | 7 | 75 | 0.30 | 0.50 | 0.50 | 0.50 | 3.05 | mid-hi |
| dissolved oxygen analysis by probe (mg/L) | 7 | 75 | 3.90 | 6.44 | 7.48 | 8.60 | 10.78 | mid-hi |
| pH (standard units) | 7 | 75 | 6.93 | 7.42 | 7.65 | 7.81 | 8.17 | mid-lo |
| total alkalinity (mg/L as CaCO3) | 7 | 71 | 38.00 | 58.00 | 68.00 | 73.50 | 83.50 | mid |
| total nonfiltrable residue (mg/L) | 7 | 74 | 4.00 | 6.00 | 9.00 | 13.00 | 24.00 | mid-lo |
| total nitrogen (mg/L as N) | 7 | 68 | 0.86 | 1.10 | 1.26 | 1.45 | 2.32 | mid-hi |
| total phosphorus (mg/L as P) | 7 | 71 | 0.05 | 0.07 | 0.09 | 0.11 | 0.50 | mid |
| total organic carbon (mg/L as C) | 7 | 69 | 10.00 | 15.00 | 16.00 | 20.00 | 29.00 | mid-hi |
| tsi | 7 | 65 | 55.09 | 59.77 | 62.39 | 65.71 | 75.73 | high |
| total calcium (mg/L as Ca) | 7 | 75 | 28.10 | 39.10 | 46.50 | 55.50 | 117.00 | mid-lo |
| total magnesium (mg/L as Mg) | 7 | 75 | 8.80 | 13.40 | 16.30 | 26.40 | 263.00 | mid-lo |
| total sodium (mg/L as Na) | 7 | 75 | 50.90 | 85.40 | 99.40 | 174.00 | 2120.00 | mid-lo |
| total potassium (mg/L as K) | 7 | 74 | 2.90 | 4.00 | 4.50 | 6.60 | 75.80 | mid-lo |
| total chloride (mg/L) | 7 | 75 | 87.00 | 150.00 | 180.00 | 330.00 | 3800.00 | mid-lo |
| total sulfate (mg/L as SO4) | 7 | 74 | 24.00 | 49.00 | 69.00 | 100.00 | 570.00 | mid-lo |
| fecal coliform (MF M-FC broth 44.5°C) | 7 | 72 | 1.00 | 1.00 | 2.50 | 7.00 | 200.00 | mid-lo |
| total filtrable residue (mg/L dried at 180°C) | 7 | 72 | 295.00 | 422.50 | 490.50 | 708.50 | 6800.00 | mid-lo |
| sample site depth (meters) | 7 | 75 | 2.60 | 5.10 | 5.40 | 5.60 | 6.40 | high |
| hardness (mg/L Ca+Mg) | 7 | 75 | 108.48 | 152.64 | 186.16 | 245.95 | 1375.18 | mid-lo |
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