To ensure the integrity of water well construction and prevent potential pollution of state groundwaters, the OWRB supervises the licensing of water well drillers and pump installers. This program is guided by comprehensive standards developed in cooperation with the Well Drillers Advisory Committee. Licensed drillers are required to submit well logs online or by mail within sixty days of the completion of a new well or plugging or reconditioning of an existing well.Well Driller Licensing Fact Sheet

Known locations of water wells within Ohio. This information was supplied to the Ohio Department of Natural Resources (ODNR) by water well contractors per the Ohio Revised Code 1521.05. Water well data was first submitted to the state back in the late 1940's. This dataset is a small subset of all the water well records maintained ODNR-Division of Water Resources. This application is intended to illustrate water wells within the State of Ohio, by status and type. These data are derived from multiple sources and the positional quality may be varied. Locations may require additional research and/or professional surveying to achieve desired accuracy. Less than 55% of the well records in the ODNR well record database have latitude and longitude values and thus only those records with known coordinates will show up on this map.

This digital dataset is comprised of three separate data files that contain total dissolved solids, well construction, and well identifying information for 3,546 water wells used to map salinity in and around 31 southern and central California oil fields. Salinity mapping was done for 27 fields located in the southern San Joaquin Valley of Kern County (North Belridge, South Belridge, Canfield Ranch, North Coles Levee, South Coles Levee, Cymric, Edison, Elk Hills, Fruitvale, Greely, Jasmin, Kern Bluff, Kern Front, Kern River, Lost Hills, Mount Poso, Mountain View, Poso Creek, Rio Bravo, Rosedale, Rosedale Ranch, Round Mountain, San Emidio Nose, Tejon, Ten Section, Wheeler Ridge, and Yowlumne), 3 fields in the LA Basin of Los Angeles County (Montebello, Santa Fe Springs, and Wilmington), and 1 field in the central coast area of Santa Barbara and San Luis Obispo Counties (Santa Maria Valley). Unlike petroleum wells, water wells both within and adjacent to oil fields of interest were used for salinity mapping. Water wells within an area (buffer) of 2-miles from the administrative field boundaries, with the exception of the Wilmington oil field with a buffer of 1-mile, were used for salinity mapping. Water wells located within overlapping buffer areas of adjacent oil fields were assigned to multiple fields for the purpose of being able to map salinity on a field-by-field basis. The dataset includes total dissolved solids (TDS) analyses from 1927 to 2016. Many of the analyses represent TDS concentrations that were calculated, as part of the salinity mapping, from specific conductance (SC) in lieu of reported TDS concentrations. Approximately 30 percent of the mapped water wells are wholly or partially derived from SC. In addition, approximately 50 percent of the water wells have TDS or SC analyses from more than one unique sample date. For wells having multiple analyses TDS represents the median value for the entire period of record, irrespective of whether it is from reported, calculated, or a combination of both TDS types. This dataset also includes ancillary data in the form of bottom perforation depth, well depth, or hole depth, land-surface elevation at the well head, and well _location and identifier information. Bottom perforation depth was missing for about 65 percent of all water wells used for salinity mapping and were assigned a alternative value for plotting purposes. Where available, well depth or hole depth were used in lieu of bottom perforation depth. For water wells lacking bottom perforation, well depth, or hole depth (40 percent), the bottom perforation was estimated based on screen length when available (5 percent), or when the median bottom perforation or median well depth for all wells associated with an individual field is provided as an approximation for the purpose of vertical plotting (35 percent). Summary data about each well used for salinity mapping is contained in the file called Water_Wells_Summary_Data. Detailed information about all individual TDS values including those used for determining median TDS values, are contained in the file called Water_Wells_All_Data. Data used for the development of linear regression equations for calculating TDS from specific conductance in lieu of reported TDS values are contained in the file called Water_Wells_Regress_Data.

Groundwater in the arid Mountain Home area is vital to agricultural, municipal, industrial and other water users who are concerned about declining groundwater levels. The U.S. Geological Survey, in cooperation with the Idaho Department of Water Resources (IDWR), developed a hydrogeologic framework to provide a conceptual understanding of groundwater resources in the Mountain Home area. As part of the hydrogeologic framework, water-table contour and groundwater-level change maps were produced to describe the occurrence, movement, and change in groundwater. Water-table contours for spring 2023 (March 20 to 24, 2023) and autumn 2023 (November 1 to 7, 2023) were created for the regional aquifer and perched groundwater zone in the Mountain Home area. The well numbers and station names for sites used to create the water-table contours and groundwater-level change and groundwater storage change rasters are provided in this data release. The location, depth to water, and groundwater altitude for these wells can be accessed on USGS National Water Information System (NWIS), IDWR groundwater portal, or an annual water level monitoring report for IDWR permit 61-12090 (HDR, 2024). The interpreted 50-foot contours of the water table are also provided in this data release. The contours are referenced to the North American Vertical Datum of 1988 (NAVD 88). The water-table contours are divided into two water-bearing units - regional and perched groundwater zone - based on well depth and groundwater altitude. The water-table contours ranged from 2,350 to 3,650 feet above NAVD 88. The groundwater-level change at well sites from spring to autumn 2023 were interpolated over the study area and are provided in a raster. Groundwater-level change ranged from 22.01 ft decline to 15.44 ft rise. Groundwater-level change was multiplied by hydrogeologic unit storativity to estimate groundwater storage change from spring to autumn 2023. More information on the generation of the water-table contours, groundwater change maps, and perched groundwater delineation and limitations can be found in the companion report, SIR 2024-5124 (Hydrogeologic framework of the Mountain Home area, southern Idaho by L.M. Zinsser and S.D. Ducar).

The High Plains aquifer extends from approximately 32 to 44 degrees north latitude and from 96 degrees 30 minutes to 106 degrees west longitude. The aquifer underlies about 175,000 square miles in parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. This digital data set contains water-level measurements from wells screened in the High Plains aquifer and measured in both predevelopment (about 1950) and for 2017. There were 2,928 wells measured in both predevelopment (about 1950) and 2017 as well as 63 wells located in New Mexico, which were measured in predevelopment and at least once between 2013 and 2016. These water-level measurements were used to map water-level changes, predevelopment (about 1950) to 2017. The map was reviewed for consistency with the relevant data at a scale of 1:1,000,000.

This dataset provides information submitted by well contractors as prescribed by Regulation 903, and is stored in the Water Well Information System (WWIS). Spatial information for all of the well records reported in Ontario are also provided. Well record map *[WWIS]: Water Well Information System This data is related to: * Well records * Map: Well records * Topic: Drinking water * Law: Reg. 903: Wells Related data: * Petroleum wells

This layer of the Map based index (GeoIndex) shows where water wells exist with data available on transmissivity, storativity and discharge/drawdown. These parameters indicate the physical characteristics of the aquifer which can relate to factors such as possible storage capacities or rate of movement of water through the rock.

This is the 2022 version of the Aquifer Risk Map. The 2021 version of the Aquifer Risk Map is available here.This aquifer risk map is developed to fulfill requirements of SB-200 and is intended to help prioritize areas where domestic wells and state small water systems may be accessing raw source groundwater that does not meet primary drinking water standards (maximum contaminant level or MCL). In accordance with SB-200, the risk map is to be made available to the public and is to be updated annually starting January 1, 2021. The Fund Expenditure Plan states the risk map will be used by Water Boards staff to help prioritize areas for available SAFER funding. This is the final 2022 map based upon feedback received from the 2021 map. A summary of methodology updates to the 2022 map can be found here.This map displays raw source groundwater quality risk per square mile section. The water quality data is based on depth-filtered, declustered water quality results from public and domestic supply wells. The process used to create this map is described in the 2022 Aquifer Risk Map Methodology document. Data processing scripts are available on GitHub. Download/export links are provided in this app under the Data Download widget.This draft version was last updated December 1, 2021. Water quality risk: This layer contains summarized water quality risk per square mile section and well point. The section water quality risk is determined by analyzing the long-tern (20-year) section average and the maximum recent (within 5 years) result for all sampled contaminants. These values are compared to the MCL and sections with values above the MCL are “high risk”, sections with values within 80%-100% of the MCL are “medium risk” and sections with values below 80% of the MCL are “low risk”. The specific contaminants above or close to the MCL are listed as well. The water quality data is based on depth-filtered, de-clustered water quality results from public and domestic supply wells.Individual contaminants: This layer shows de-clustered water quality data for arsenic, nitrate, 1,2,3-trichloropropane, uranium, and hexavalent chromium per square mile section. Domestic Well Density: This layer shows the count of domestic well records per square mile. The domestic well density per square mile is based on well completion report data from the Department of Water Resources Online System for Well Completion Reports, with records drilled prior to 1970 removed and records of “destruction” removed.State Small Water Systems: This layer displays point locations for state small water systems based on location data from the Division of Drinking Water.Public Water System Boundaries: This layer displays the approximate service boundaries for public water systems based on location data from the Division of Drinking Water.Reference layers: This layer contains several reference boundaries, including boundaries of CV-SALTS basins with their priority status, Groundwater Sustainability Agency boundaries, census block group boundaries, county boundaries, and groundwater unit boundaries. ArcGIS Web Application

This map provides access to the Board of Water Well Contractors drillers’ reports. Well drillers’ reports are required to be filed with the State Board of Water Well Contractors within 30 days after completion or abandonment of a well.

Constraints:
Not to be used for navigation, for informational purposes only. See full disclaimer for more information

The U.S. Geological Survey (USGS) is providing a compilation of geologic well records (n=221) collected from 2014-2020 within the Binghamton East 1:24,000 quadrangle in south-central Broome County, New York. The well records were obtained from: 1) previous U.S. Geological Survey groundwater investigations, 2) the U.S. Geological Survey’s National Water Information System (NWIS), 3) the New York State Department of Environmental Conservation (NYSDEC) Water Well Contractor Program, and 4) the New York State Department of Transportation (NYSDOT). The dataset is in comma-separated values (CSV) format. A companion report, USGS Scientific Investigations Report 2021-5026 (Van Hoesen and others, 2021; https://doi.org/10.3133/sir20215026) further describes data collection and map preparation.

A well is a hole dug into the ground usually for the purpose of taking water from the ground but also for monitoring groundwater. Most private wells are used for home and farm water supplies are in rural areas. Springs occur where groundwater comes out at the surface. A borehole is a hole drilled into the ground to gain access to groundwater. The hole is usually deep, narrow and round. This map shows the location of the dug wells, springs and boreholes in Ireland. Data was collected by GSI drilling or submitted to the GSI from Local Authorities and other state bodies, Private Well Grants, Drillers, Consultants, Group Water Schemes and Academia. The location accuracy is visually portrayed on the GSI webmapping viewer by the size of the circle displaying the record. It is NOT a comprehensive database and many wells and springs are not included in this database. You should not rely only on this database, and should undertake your own site study for wells in the area of interest if needed. This map is to the scale 1:100,000. This means it should be viewed at that scale. When printed at that scale 1cm on the map relates to a distance of 1km. It is a vector dataset. Vector data portray the world using points, lines, and polygons (areas). The data is shown as polygons. Each polygon holds information on the location of the borehole (X and Y coordinates), Well ID (well identifier), hole details, location details, yield, abstraction ,drilling details.

Water wells in Missouri

The High Plains aquifer extends from about 32 degrees to almost 44 degrees north latitude and from about 96 degrees 30 minutes to 106 degrees west longitude. The aquifer underlies about 175,000 square miles in parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. This digital dataset is comprised of water-level measurements from 7,195 wells measured in both 2017 and 2019, which were used to map water-level changes, 2017 to 2019. The map was reviewed for consistency with the relevant data at a scale of 1:1,000,000.

The data in these six files is derived from Wellogic, the EGLE statewide ground water database. The six files combined contain information on over 575,000 spatially verified water well records. The six files are intended to provide water well information for wells in counties clustered by geographic region: Upper Peninsula, Northern Lower Peninsula, East Central Lower Peninsula, West Central Lower Peninsula, Southwest Lower Peninsula and the South Central – Southeastern Lower Peninsula. The files are constructed to be easily merged, containing the same number and type of attribute fields. Although the derived data in these files represents the best readily available data, the six files do not represent a complete database of all wells or well records in existence. Beginning January 1, 2000 virtually 100% of new wells constructed are accounted for in Wellogic, however for wells older than 2000 the rate of inclusion varies from county to county, and may be considerably lower. Further, there is a quality control check on location that may exclude a limited number of wells from Wellogic from the six files made available on this site. The locational data also has varying degrees of accuracy; ranging from precise GPS point collection to address geocoding, but there may also be erroneous locations regardless of collection method that have not been corrected as of yet. Refer to the METHD_COLL field to determine each individual record’s potential locational accuracy. Field codes described below.------------------------------------------------------------------------------------------Field Definitions:WELLID : Wellogic ID number (unique identifying number, first 2 digits represent county number)PERMIT_NUM : Well permit number as assigned by local health departmentWELL_TYPE : Type of wellOTH = OtherHEATP = Heat pumpHOSHLD = HouseholdINDUS = IndustrialIRRI = IrrigationTESTW = Test wellTY1PU = Type I publicTY2PU = Type II publicTY3PU = Type III publicTYPE_OTHER : Type of well if WELL_TYPE is 'OTH'WEL_STATUS : Status of wellOTH = OtherACT = ActiveINACT = InactivePLU = Plugged/AbandonedSTATUS_OTH : Status of well if WEL_STATUS is 'OTH' WSSN : Water Supply Serial Number, only if public wellWELL_NUM : Individual well number/name, only if public wellDRILLER_ID : Water Well Drilling Contractor Registration Number as assigned by State of Michigan DRILL_METH : Method used to drill the well boreholeOTH = OtherAUGBOR = Auger/BoredCABTOO = Cable ToolCASHAM = Casing HammerDRIVEN = Driven HandHOLROD = Hollow RodJETTIN = JettedMETH_OTHER : Method used to drill if DRILL_METH is 'OTH'CASE_TYPE : Well casing typeOTH = OtherUNK = UnknownPVCPLA = PVC PlasticSTEBLA = Steel-blackSTEGAL = Steel-GalvanizedCASE_OTHER : Well casing type is CASE_TYPE is 'OTH'CASE_DIA : Well Casing Diameter (in inches)CASE_DEPTH : Depth of Casing (in feet) SCREEN_FRM : Depth of top of screen (in feet)SCREEN_TO : Depth of bottom of screen (in feet)SWL : Depth of Static Water Level (in feet)FLOWING : Naturally flowing well (Y or N)AQ_TYPE : Aquifer typeDRIFT = Well draws water from the glacial driftROCK = Well draws water from the bedrockDRYHOL = Dry hole, well did not produce waterUNK = UnknownTEST_DEPTH : Depth of drawdown when the well was developed (in feet)TEST_HOURS : Duration of pumping when the well was developed (in hours)TEST_RATE : Rate of water flow when the well was developed (in Gallons per Minute)TEST_METHD : Method used to develop the wellUNK = UnknownOTH = OtherAIR = AirBAIL = BailerPLUGR = PlungerTSTPUM = Test Pump TEST_OTHER : Method used to develop the well if TEST_METHD is 'OTH'GROUT : Whether the well was grouted or notPMP_CPCITY : Capacity of the pump installed in the well (in Gallons per minute)METHD_COLL : Method of collection of the latitude/longitude coordinates001 = Address Matching-House Number002 = Address Matching-Street Centerline004 = Address Matching-Nearest Intersection012 = GPS Carrier Phase Static Relative Position Tech.013 = GPS Carrier Phase Kinematic Relative Position Tech.014 = GPS Code Measurement Differential (DGPS)015 = GPS Precise Positioning Service016 = GPS Code Meas. Std. Positioning Service SA Off017 = GPS Std. Positioning Service SA On018 = Interpolation-Map019 = Interpolation-Aerial Photo020 = Interpolation-Satellite Photo025 = Classical Surveying Techniques027 = Section centroid028 = TownRange centroid036 = Quarter-Quarter-Quarter centroidELEV_METHD : Method of collection of the elevation003 = GPS Code Measurement Differential (DGPS)005 = GPS Code Meas. Std. Positioning Svc. SA Off007 = Classical Surveying Techniques014 = Topographic Map InterpolationOTH = OtherUNK = UnknownWITHIN_CO: Whether the well is within the stated countyWITHIN_SEC: Whether the well is within the stated land survey sectionLOC_MATCH: Whether the well is within the stated Tier/RangeSEC_DIST: Whether the well point is within 200 feet of the stated land survey sectionELEV_DEM: Elevation in feet above mean sea levelELEV_DIF: Absolute difference, in feet, between ELEVATION and ELEV_DEMLANDSYS: The Land System Group polygon that the well falls withinDEPTH_FLAG:1: WELL_DEPTH = 02: WELL_DEPTH < 25ft or WELL_DEPTH > 1000ftELEV_FLAG:1: ELEVATION (Wellogic Field) =02: ELEVATION (Wellogic Field) < 507ft OR > 1980ft3: ELEVATION (Wellogic Field) < DEM min OR > DEM max4: ELEV_DIF > 20 ftSWL_FLAG:1: SWL = 02: SWL >= WELL_DEPTH in a Bedrock well OR SWL >= SCREEN_BOT in a Glacial well3: SWL > 900ftSPC_CPCITY: Specific Capacity = (TEST_RATE / TEST_DEPTH). Only calculated if TEST_METHD = BAIL, PLUGR or TSTPUMAQ_CODE:N: No Lithology Record associated with the well recordB: Blank (AQTYPE = null) noted among the strataD: Drift (Glacial) WellR: Rock WellU: Unknown Lithology noted among the strata* PROCESSING NOTE – This evaluation reads the [AQTYPE] field for each stratum from the LITHOLOGY table, beginning at the top and looping down to each subjacent stratum. If the previous stratum = ‘R’ AND the bottommost stratum = ‘R’, then [AQ_CODE] is set to ‘R’. If the previous stratum = ‘R’ AND the next stratum = ‘D’, then [AQ_CODE] is set to ‘D’ and [AQ_FLAG] is set to ‘L’. If aType = ‘R’ AND screendepth > 0 R’ AND screendepth <= welldepth, then [AQ_CODE] is set to ‘D’ and [AQ_FLAG] is set to ‘S’. If aType = ‘R’ AND welldepth <= topofrock, then [AQ_CODE] is set to ‘D’ and [AQ_FLAG] is set to ‘D’.

New York State registered water well drillers are required to submit completion reports documenting where wells have been drilled, the specifications of those wells, and any subsequent work performed on those wells. Data regarding water wells has been collected since April 2000 as required by ECL 15-1525. Completion reports for the wells are added as they become available. Historical wells are added as the wells are mapped. Well locations are generally accurate to the parcel scale but may not represent the exact location on the property.Service layer is updated annually, and last updated 02/18/2025.For more information see https://dec.ny.gov/environmental-protection/water/water-quantity/water-well-contractor-program1. The NYS DEC asks to be credited in derived products.2. Secondary Distribution of the data is not allowed.3. Any documentation provided is an integral part of the data set. Failure to use the documentation in conjunction with the digital data constitutes misuse of the data.4. Although every effort has been made to ensure the accuracy of information, errors may be reflected in the data supplied. The user must be aware of data conditions and bear responsibility for the appropriate use of the information with respect to possible errors, original map scale, collection methodology, currency of data, and other conditions.

Data from more than 75,000 community public supply wells were acquired from national and state agencies. Using the information provided by the agencies, along with surficial and bedrock geologic maps, the wells were assigned to a national Principal Aquifer (PA) as defined in USGS (2003) or a Secondary Hydrogeologic Region (SHR) as defined in Belitz et al. (2018). Collectively, both PAs and SHRs are referred to as Hydrogeologic Regions (HRs). The HR identifies the primary source of water for the well. The locations of the wells were generalized so that they plot in the center of a 2 kilometer square grid. The county information provided identifies the county the well is located within based on it’s actual location, not the generalized location. A total of 76,354 wells were assigned to an HR, 41 wells were assigned to "basement" or "bedrock" because there was not enough information to assign to a specific HR.

The Aquifer Risk Map Web Tool contains all archived maps, including this 2023 Aquifer Risk Map.The Aquifer Risk Map is developed to fulfill requirements of SB-200 (Monning, 2019) and is intended to help prioritize areas where domestic wells and state small water systems may be accessing groundwater that does not meet primary drinking water standards (maximum contaminant level or MCL). In accordance with SB-200, the map is made available to the public and updated annually starting January 1, 2021. This web map is part of the 2023 Aquifer Risk Map. The Fund Expenditure Plan states the risk map will be used by Water Boards staff to help prioritize areas for available SAFER funding.

This web map includes the following layers:Water Quality Risk: water quality risk estimates per square mile section for all contaminants with an MCL. Water quality risk is listed as “high” (average or recent concentration in section is above MCL for one or more contaminants), “medium” (average or recent concentration in section is between 80% - 100% of MCL for one or more contaminants), “low” (average or recent concentration in section is less than 80% of MCL for all measured contaminants) or “unknown” (no water quality data available in section).Individual Contaminant Risk: water quality risk estimates for nitrate, arsenic, 1,2,3-trichloropropane, hexavalent chromium, and uranium per square mile section.State Small Water Systems (DDW): state small water systems (5-14 connections) location from the Division of Drinking Water joined with water quality risk section estimates from the 2023 Aquifer Risk Map.Domestic Well Records (OSWCR): the approximate count and location of domestic well completion reports submitted to the Department of Water Resources. This is used as a proxy to identify domestic well locations.Public Water System Boundaries (DDW): the approximate boundaries of public drinking water systems, from the Division of Drinking Water. For reference only.Census Areas: Census block groups and census tract boundaries containing demographic information from the 2021 American Community Survey (B19013 Median Household Income and B03002 race/ethnicity) joined with summarized water quality risk estimates from the 2023 Aquifer Risk Map (count of high risk domestic wells and state small water systems per census area).Reference Boundaries: Various geographic boundaries including counties, basins, GSA’s, CV-SALTS basin prioritization status, Disadvantaged Community (DAC) status, and legislative boundaries. For reference only.CalEnviroScreen 4.0: CalEnviroScreen scores from OEHHA. For reference only.Groundwater Level Percentiles (DWR): Groundwater depth in various monitoring wells compared to the historic average at that well. For reference only.

The water quality risk is based on depth-filtered, de-clustered water quality results from public and domestic supply wells. The methodology used to determine water quality risk is outlined here. For more information about the SAFER program, please email SAFER@waterboards.ca.gov. For technical questions or feedback on the map please email GAMA@waterboards.ca.gov.

The King County Groundwater Protection Program maintains a database of groundwater wells, water quality and water level sampling data. Users may search the database using Quick or Advanced Search OR use King County Groundwater iMap map set. The viewer provides a searchable map interface for locating groundwater well data.

The exported ESRI point shapefile 'allwells' was made using Arc Map 8.2 on a Win2000 pc The points were created from a download of the informix data base in June, 2002. Source of the location of the points varies. All State Plane Coordinates were entered by the applicant as the location of his well, usually from looking at a 1:24k USGS topographical map. A UTM coordinate is calculated to the center of the third quarter, or the smallest quarter of a section of land within the Public Land Survey System (PLSS). These quarters were also identified by the applicant as the location of the well. If no quarter was given, the UTM coordinate is calculated to the center of the section. The Bureau of Land Management's GCDB *.lx files were used to plot the wells in the database that are entered by section, quarter, quarter, quarter description. Points that were originally located in the State Plane Coordinate system were projected using ArcInfo to UTM Zone 13, NAD83. The final data set is projected in UTM Zone 13, NAD83. Attributes found with this coverage are downloaded from the OSE WATERS database with the exception of X-coord, y-coord which were calculated. Accuracy of well informatioin will be greatly enhanced when the entire state has been abstracted.

This release of data includes the chloride concentration of water samples provided by the USGS or other organizations that were used for this mapping effort. The inland extent of saltwater at the base of the Biscayne aquifer in the Model Land area of Miami-Dade County, Florida, was mapped in 2011. Since that time, the saltwater interface has continued to move inland. The interface is near several active well fields; therefore, an updated approximation of the inland extent of saltwater and an improved understanding of the rate of movement of the saltwater interface are necessary. A geographic information system was used to create a map using the data collected by the organizations that monitor water salinity in this area. A rate of saltwater interface movement of 140 meters per year was estimated by dividing the distance between two monitoring wells (TPGW-7L and Sec34-MW-02-FS) by the travel time. The travel time was determined by estimating the dates of arrival of the saltwater interface at the wells and computing the difference. This estimate assumes that the interface is traveling east to west between the two monitoring wells. Although monitoring is spatially limited in this area and some of the wells are not ideally designed for salinity monitoring, the monitoring network in this area is improving in quality and spatial distribution. The approximation of the inland extent of the saltwater interface and the estimated rate of movement of the interface are dependent on existing data. Improved estimations could be obtained by installing uniformly-designed monitoring wells in systematic transects extending landward of the advancing saltwater interface.