St. Johns River Water Management District St. Johns River Water Management District St. Johns River Water Management District St. Johns River Water Management District St. Johns River Water Management District St. Johns River Water Management District
St. Johns River Water Management District - www.sjrwmd.com

www.sjrwmd.com

Online tools, GIS, data

19020002 (Nassau River)

Site Photograph

Basin characterization

680.738 km²

Location: latitude 30°34’29.720”, longitude 81°36’31.088”, GPS datum—WGS-1984 Station 19020002 is on the Nassau River at U.S. Highway 17.

Point sources: There are no wastewater treatment facilities upstream within a five-mile radius and within the drainage basin of this site.

Site Photograph

The sampling site is located on the Nassau River at U.S. Highway 17, approximately 4 miles south of Yulee, Fla. There is a private boat ramp located at a fish camp on the north side of the bridge and boaters may use the ramp for a small fee. Highway 17 is an extremely busy roadway and caution is advised when entering or leaving the fish camp.

The area is a coastal marine environment, dominated by salt marsh, and is sparsely populated. It offers great fishing and the local fish camp offers fishing tournaments throughout the year. The city of Fernandina Beach and the resorts of Amelia Island are located approximately 10 miles to the northeast and offer many opportunities for visitors, such as golf, boating, shopping, dining, and the beach.

Site and Watershed Locator Map

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 going to the Technical background page. From that page, a description of the customized GIS data summary tool can be accessed.

Spatial data summaries

Download spatial data summaries Excel Icon

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.

Watershed 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.

Watershed General Land Use

Watershed Geology
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.


Watershed 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.

Watershed 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.

Watershed Rainfall

St. Johns River Water Management District 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 acres 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.

Watershed 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.

Watershed 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).

Watershed 5-Foot Elevation

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.

Watershed Recharge

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 websites (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 in the map legend below refers to the district’s Water Resource Information 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.

Arc Hydro Model Graphic

Clicking on the Methodology link will direct you to information about how water quality samples were collected, analyzed, and summarized for this fact page. View the most recent Water Quality Status and Trends Report.

Water quality

Download water quality data

The Nassau River is sampled monthly at U.S. Highway 17, in northern Duval County, under a Florida Department of Environmental Protection (DEP) contract. The river is about 5.55 meters deep at the sample site and has a typical temperature range. At the sampling site, the river is tidally influenced, and the area exhibits characteristics of an estuary. Although conductivity measurements are a little low for estuaries, the major ion concentrations are high, resulting in very hard water. The median dissolved oxygen value is slightly lower than typically found in district estuaries. The water has fair buffering capacity and a neutral pH. The low Secchi depth is most likely due to elevated concentrations of total organic carbon and color. Concentrations of total suspended solids, turbidity, total nitrogen, total phosphorus, chlorophyll, and coliform counts were all higher than what is typically found in an estuary. The site has fair water quality, according to the trophic state index.x.

Analytes Data Yrs N Data Min Q1 Median Q3 Max Range
Water temperature (°C) 14 137 10.20 16.51 21.79 27.60 30.99 mid-lo
Secchi disc transparency (meters) 13 72 0.20 0.30 0.48 0.60 1.10 low
Color (platinum-cobalt units) 14 135 50.00 100.00 150.00 250.00 600.00 high
Specific conductance (µhmhos/cm @ 25° C) 14 137 134.00 4757.00 15700.00 26660.00 49140.00 mid-lo
Sample collection depth (meters) 14 137 0.30 0.30 0.50 0.50 0.50 mid-hi
Dissolved oxygen analysis by probe (mg/L) 14 136 1.62 4.62 5.99 7.54 11.60 mid-lo
pH (standard units) 14 136 5.11 6.64 6.90 7.08 7.52 low
Total alkalinity (mg/L as CaCO3) 14 134 8.00 33.00 54.00 74.00 115.00 mid-lo
Total nonfiltrable residue (mg/L) 14 136 3.00 16.00 25.00 38.50 300.00 mid-hi
Total nitrogen (mg/L as N) 14 127 0.49 0.99 1.21 1.42 2.23 mid-hi
Total phosphorus (mg/L as P) 14 130 0.04 0.10 0.13 0.18 1.70 high
Total organic carbon (mg/L as C) 14 132 4.80 14.00 20.00 25.45 48.40 high
Total calcium (mg/L as Ca) 13 27 41.37 47.64 55.12 57.20 74.53 mid-hi
Total magnesium (mg/L as Mg) 14 136 5.00 38.45 123.50 220.50 399.00 mid-hi
Total sodium (mg/L as Na) 14 136 3.20 98.30 346.50 661.50 1210.00 mid-hi
Total potassium (mg/L as K) 14 136 16.50 915.50 3005.00 5295.00 9680.00 mid-hi
Total chloride (mg/L) 14 136 1.90 32.15 107.50 194.50 427.00 mid-hi
Total sulfate (mg/L as SO4) 14 136 25.00 1450.00 5330.00 9800.00 19000.00 mid-hi
wqi 14 136 0.43 195.00 675.00 1300.00 2500.00 mid-hi
fecal coliform (MF M-FC broth 44.5° C) 14 125 1.00 18.00 39.00 64.00 5100.00 high
Trichromatic uncorrected chlorophyll-a (µg/L) 14 30 0.01 1.60 7.67 11.00 113.00 mid-hi
Hardness (mg/L Ca+Mg) 14 136 27.29 501.56 1773.48 3272.15 5971.59 mid-hi
Total filtrable residue (mg/L dried at 180° C) 14 134 124.00 2490.00 8640.00 16700.00 32200.00 mid-hi
Lab turbidity (NTU) 14 136 0.20 5.80 8.60 13.00 40.00 high
Sample site depth (meters) 14 134 1.00 3.30 5.55 7.60 11.70 high

Careers

In this section
Highlights
More about
Careers

Search www.sjrwmd.com

Governing Board meetings
Please see agendas for specific meeting times, which may differ monthly.

Lobbyist registration requirements

Other district meetings and notices

Central Florida Water Initiative

Tell us how
we are doing.

Take our survey on
customer service.

By accessing this site, you agree to accept terms and conditions of the district’s liability disclaimer.

Employee Portal

St. Johns River Water Management District
4049 Reid Street, Palatka, FL 32177
(800) 725-5922