Water Quality Surfaces of the Upper Floridan Aquifer

*** Metadata updated 06.24.2010 by jstokes@sjrwmd.com ***
 
Water quality monitoring of the Floridan aquifer provides useful information for water resource protection and water supply planning. Water quality monitoring provides information to evaluate groundwater resources on regional and subregional scales, detect long-term trends, identify potential problem areas, and provide information to determine the effectiveness of water management programs. The major focus of SJRWMD groundwater quality monitoring is the Floridan aquifer system, which is the primary source of water for public supply and other uses in most areas. 

The chemical composition of water and the physical properties of water in an aquifer represent the net effect of the processes that have dissolved, altered, or precipitated the chemical constituents. These datasets depict chloride (Cl), sulfate (SO4) or total dissolved solids (TDS) concentration variability in the Upper Floridan Aquifer.

The major focus of SJRWMD groundwater quality monitoring is the Floridan aquifer system (FAS), which is the primary source of water for public supply and other uses in most areas. Regional groundwater quality conditions in the FAS are the result of regional hydrogeologic features, climatic conditions, and long-term water use trends. Data analysis from a regional perspective allows for network optimization by minimizing monitoring wells and sampling frequency in areas that have shown insignificant variability, allowing for additional monitoring in areas where significant variability has been documented or is projected to occur. 

Subregional monitoring assesses groundwater quality related to localized hydrogeologic features and stresses to the aquifer system, such as water withdrawals. The data are used to describe localized spatial variability, temporal water quality changes, and water quality variability with depth in an aquifer. The monitoring well network includes increased well coverage and sampling frequency in areas that have increasing trends in water quality variables, in areas near the potable and nonpotable groundwater interface, in areas of seawater intrusion along parts of the Atlantic coast, and in areas with projected water level drawdowns. 

Most network wells monitor the Upper Floridan aquifer, with additional wells monitoring the Avon Park permeable zone and the Lower Floridan aquifer. Monitoring well clusters provide information on the characteristics of the hydrostratigraphic units with depth.

Chloride (Cl) concentration variability in the Upper Floridan aquifer is of primary concern in the use of water from the Floridan aquifer for public supply. The secondary drinking water standard for chloride is 250 milligrams per liter.

Sulfate (SO4) concentration variability in the Upper Floridan aquifer is of primary concern in the use of water from the Floridan aquifer for public supply. The secondary drinking water standard for sulfate is 250 milligrams per liter.

Total dissolved solids (TDS) concentration variability in the Upper Floridan aquifer is of primary concern in the use of water from the Floridan aquifer for public supply. The secondary drinking water standard for TDS is 500 milligrams per liter.

The Upper Floridan chloride concentration map was originally produced in 2001 using median chloride concentration data from SJRWMD monitoring well water quality sampling and knowledge of the hydrogeologic system. The median chloride concentration data were input into a geostatistical computer program (Isatis) and a kriged chloride surface was estimated. Next, the chloride contours were checked and edited using the chloride data values. The chloride concentration contours were then smoothed by taking into account Floridan aquifer recharge and discharge areas, proximity to saltwater bodies, and comparing the contours with previously published water quality maps.

The Upper Floridan chloride concentration map was refined in June 2010 using updated median chloride data from water quality sampling through October 2009, in additional to chloride data from new monitoring wells. Manual digital editing of the contour line features was performed by GIS Analyst, according to the groundwater quality expertise of Dr. David Toth. The range of median chloride concentration values used as input to this update was 2 mg/L to 16,600 mg/L. The chloride contour interpretations were keyed to the number of observations, with wells sampled 3 or more times given more weight than wells with only one or two samples. 

The chloride concentration is divided into 4 zones (field: CL2_ZONE) which corresponds to a concentration range (field: MGL_RANGE). 
 
CL2_ZONE        MGL_RANGE (mg/L)
 1                      0-50
 2                      50-250
 3                      250-1000
 4                      Greater than 1000

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The Upper Floridan sulfate concentration map was originally produced in 2001 using median sulfate concentration data from SJRWMD monitoring well water quality sampling and knowledge of the hydrogeologic system. The median sulfate concentration data were input into a geostatistical computer program (Isatis) and a kriged sulfate surface was estimated. Next, the sulfate contours were checked and edited using the sulfate data values. The sulfate concentration contours were then smoothed by taking into account Floridan aquifer recharge and discharge areas, proximity to saltwater bodies, and comparing the contours with previously published water quality maps.

The Upper Floridan sulfate concentration map was refined in June 2010 using updated median sulfate data from water quality sampling through October 2009, in additional to sulfate data from new monitoring wells. Manual digital editing of the contour line features was performed by GIS Analyst, according to the groundwater quality expertise of Dr. David Toth. The range of median sulfate concentration values used as input to this update was 0.2 mg/L to 2,000 mg/L. The sulfate contour interpretations were keyed to the number of observations, with wells sampled 3 or more times given more weight than wells with only one or two samples. 

The sulfate concentration is divided into 4 zones (field: SO4_ZONE) which corresponds to a concentration range (field: MGL_RANGE).
 
SO4_ZONE        MGL_RANGE (mg/L)
 1                      0-100
 2                      100-250
 3                      250-1000
 4                      Greater than 1000

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The Upper Floridan TDS concentration map was originally produced in 2001 using median TDS concentration data from SJRWMD monitoring well water quality sampling and knowledge of the hydrogeologic system. The median TDS concentration data were input into a geostatistical computer program (Isatis) and a kriged TDS surface was estimated. Next, the TDS contours were checked and edited using the TDS data values. The TDS concentration contours were then smoothed by taking into account Floridan aquifer recharge and discharge areas, proximity to saltwater bodies, and comparing the contours with previously published water quality maps.

The Upper Floridan TDS concentration map was refined in June 2010 using updated median TDS data from water quality sampling through October 2009, in additional to TDS data from new monitoring wells. Manual digital editing of the contour line features was performed by GIS Analyst, according to the groundwater quality expertise of Dr. David Toth. The range of median TDS concentration values used as input to this update was 59 mg/L to 26,000 mg/L. The TDS contour interpretations were keyed to the number of observations, with wells sampled 3 or more times given more weight than wells with only one or two samples. 

The TDS concentration is divided into 4 zones (Attribute:TDS_ZONE) which correspond to a concentration range (Attribute) MGL_RANGE (MGL = Milligrams per liter).
 
TDS_ZONE       MGL_RANGE (mg/L)           
1                      0-500
2                      500-1000
3                      1000-3000
4                      Greater than 3000