This data set represents the extent of the South coast aquifer in Puerto Rico.

This is polygon data of shallowest principal aquifers of Puerto Rico and the United States Virgin Islands, developed as part of the effort to produce a map published at 1:500,000 in Chapter HA 730-N of the "Ground Water Atlas of the United States" series of printed publications. See Other_Citation_Details for publication information. The published map contains base and cultural features not included in this data. The Ground Water Atlas publication also includes information that may be relevant to the use of this data, such as figures showing where an aquifer may extend beyond the area delineated in this data, but be overlain by one or more other aquifers and/or low-permeability material. The areal extent of the aquifers, as shown in this data, represent the area in which a named aquifer is the shallowest of the principal aquifers. These aquifer areas are not necessarily the only area in which ground water can be withdrawn because the aquifers shown may have a larger areal extent than is represented here. The boundaries in this data generally represent an interpretation of the surface location (outcrop), or near surface location (shallow subcrop) of the uppermost principal aquifer for the area. An aquifer may extend beyond the area shown in this data, but be overlain by one or more other aquifers, and/or low-permeability material. These aquifer outcrop and shallow subcrop boundaries represent broad, regional categories and should not be interpreted as site specific. Comments regarding the names of aquifers, or the hydrogeologic interpretation of the aquifers can be can be directed to the USGS Water Resources Division, Office of Ground Water, Roy Sonenshein, sunshine@usgs.gov, (305) 526-2895.

A groundwater level survey and reconnaissance of the hydrologic conditions in the South Coast aquifer in the Santa Isabel area of southern Puerto Rico was conducted during March 31 to April 17, 2014. The field survey included groundwater level measurements at 55 wells and instantaneous streamflow measurements at 15 locations in streams and irrigation canals. A potentiometric surface map of the alluvial aquifer provides an indication of the directions of groundwater flow. The objective of the field survey was to delineate the potentiometric surface of the study area defined as the South Coast aquifer between the Río Descalabrado to the west and the Río Jueyes to the east of the town of Santa Isabel. Instantaneous streamflow measurements were made at selected sites along the Río Coamo, Río Descalabrado, Río Cañas, and the Canal de Juana Díaz to evaluate groundwater and surface-water interactions during the synoptic survey. Potentiometric contours are based on water-level measurements collected at wells during the dry season from March 31 to April 17, 2014. Measured values of the potentiometric surface ranged from -22.80 feet to 185.4 feet above mean sea level. The results of the study indicate a cone of depression in the aquifer near the center of the study area, where the potentiometric surface is below mean sea level.

A groundwater level survey and reconnaissance of the hydrologic conditions in the South Coast aquifer in the Santa Isabel area of southern Puerto Rico was conducted during March 31 to April 17, 2014. The field survey included groundwater level measurements at 55 wells and instantaneous streamflow measurements at 15 locations in streams and irrigation canals. A potentiometric surface map of the alluvial aquifer provides an indication of the directions of groundwater flow. The objective of the field survey was to delineate the potentiometric surface of the study area defined as the South Coast aquifer between the Río Descalabrado to the west and the Río Jueyes to the east of the town of Santa Isabel. Instantaneous streamflow measurements were made at selected sites along the Río Coamo, Río Descalabrado, Río Cañas, and the Canal de Juana Díaz to evaluate groundwater and surface-water interactions during the synoptic survey. Potentiometric contours are based on water-level measurements collected at wells during the dry season from March 31 to April 17, 2014. Measured values of the potentiometric surface ranged from -22.80 feet to 185.4 feet above mean sea level. The results of the study indicate a cone of depression in the aquifer near the center of the study area, where the potentiometric surface is below mean sea level.

These data contain groundwater level measurements at 55 locations, used in construction of the potentiometric map of the South Coast aquifer in the Santa Isabel area of southern Puerto Rico during March 31 to April 17, 2014. Measured values of the potentiometric surface ranged from -22.8 feet to 185.4 feet above mean sea level.

These data contain groundwater level measurements at 55 locations, used in construction of the potentiometric map of the South Coast aquifer in the Santa Isabel area of southern Puerto Rico during March 31 to April 17, 2014. Measured values of the potentiometric surface ranged from -22.8 feet to 185.4 feet above mean sea level.

These data contain the estimated locations of potentiometric contours of the South Coast aquifer in the Santa Isabel area of southern Puerto Rico during March 31 to April 17, 2014.

This data set represents the extent of the Texas coastal uplands aquifer system in Texas.

This data set represents the extent of the Texas coastal uplands aquifer system in Texas.

The data set pp1773_extents contains polygon datasets that represent the areal extents of each of the 16 hydrogeologic units of the of the Atlantic Coastal Plain of North and South Carolina. [The total areal extent includes a small area in southeastern Virginia, the Atlantic Coastal Plain within North Carolina and South Carolina, and a region in southeast Georgia within the Atlantic Coastal Plain.] Each hydrogeological unit is referred to as its model layer number as represented in the report PP1773. For clarity, they are listed below along with the aquifer unit or confining unit name in North Carolina and its correlated unit name in South Carolina. L1 Surficial aquifer L2 Yorktown confining unit / Upper Floridan confining unit L3 Yorktown aquifer / Upper Floridan aquifer L4 Castle Hayne - Pungo River confining unit / Middle Floridan confining unit (To be referred to as "Castle Hayne / Middle Floridan confining unit" in this document) L5 Castle Hayne - Pungo River aquifer / Middle Floridan aquifer (To be referred to as "Castle Hayne - Middle Floridan aquifer" in this document) L6 Beaufort confing unit / Gordon confining unit L7 Beaufort aquifer / Gordon aquifer L8 Peedee confining unit / Crouch Branch confining unit L9 Peedee aquifer / Crouch Branch aquifer L10 Black Creek confining unit / McQueen Branch confining unit L11 Black Creek aquifer / McQueen Branch aquifer L12 Upper Cape Fear confining unit / Charleston confining unit L13 Upper Cape Fear aquifer / Charleston aquifer L14 Lower Cape Fear confining unit / Gramling confining unit L15 Lower Cape Fear aquifer / Gramling aquifer L16 Lower Cretaceous confining unit and aquifer Spatial data set pp1773_layer1_extent represents the extent of the top of the surficial aquifer, which is Layer 1 in the groundwater model used to simulate the aquifer system described in PP 1773. The surficial aquifer is the uppermost aquifer. It is an unconfined aquifer that is uniformly present except where it is incised by streams. The top of the surficial aquifer is equivalent to the land surface. The extent was derived primarily by geologic and hydraulic properties, as the surficial aquifer is an unconfined layer primarily composed of sediments of Quaternary age, plus some older sediments in areas due to a different stratigraphic position of the first underlying confining layer. Spatial data set pp_1773_layer_2 is the Yorktown/Upper Floridan confining unit. It is not composed of a single unit because the unit's series of clay and silt beds vary greatly in stratigraphic position. Spatial dataset pp1773_layer3_extent represents the extent of the Yorktown/Upper Floridan aquifer. The Yorktown aquifer is present only in the northern half of the North Carolina Coastal Plain. Outliers exist in Robeson, Bladen and Dublin counties, but are not separated from the surficial aquifer by a confining unit, and not considered a distinct aquifer in these areas. The Upper Floridan aquifer extent covers a southern portion of South Carolina and southern portion of Georgia. Spatial dataset pp1773_layer4_extent represents the extent of the Castle Hayne/Middle Floridan confining unit. The Castle Hayne confining unit consists of beds of clay and silt that vary in stratigraphic position and are absent in a number of areas in the central and southern North Carolina Coastal Plain. The Middle Floridan confining unit extends from South Carolina to southern Georgia. It is not continuous with the Castle Hayne confining unit. Spatial dataset pp1773_layer5_extent represents the extent of the Castle Hayne/Middle Floridan aquifer. The Castle Hayne aquifer is located in the central and southern North Carolina Coastal Plain; the Middle Floridan aquifer is more south, in southern South Carolina and southern Georgia. Spatial dataset pp1773_layer6_extent represents the extent of the Beaufort/Gordon confining unit. The Beaufort confining unit is located in northeastern North Carolina and southeastern Virginia. It is best developed in