Joining EPHT Data to GIS Layers

Joining EPHT data to a Geographic Information System (GIS) layer allows for creating map visualizations in desktop and web GIS, as well as spatial analysis of the data.

The ADHS Open GIS Data Portal has the following geographies (GIS layers) available for joining downloaded EPHT data:

• Counties
• Primary Care Areas (PCAs; sub-county)
• Public Water System (PWS) Areas
• Groundwater Basins

The following step-by-step instructions walk you through joining a EPHT downloaded data file to the corresponding GIS layer

Step 1: Download the GIS layer

Use the links below to preview and download the shapefiles for the geography layers found in the Arizona EPHT Explorer. Be sure to download the corresponding GIS layer for your downloaded EPHT data.

• States
• Counties
• PCAs (Subcounty)
• Public Water Systems (PWS) Service Areas
• Groundwater Basins

Step 2: Prepare your data

1. Ensure that your shapefile and data table are the same EPHT geography (counties, PCAs, etc) and contain a field called “GeogID”. The “GeogID” field is used for joining the EPHT data to the GIS layer, and contains matching values in both datasets.
2. Save the EPHTdata Excel file (.xlsx) found in the EPHTdatadownload folder as a CSV file (.csv).

Step 3: Open your desktop GIS software (ArcGIS Pro, QGIS, etc)

Step 4: Create a new project or open an existing one

Start a new project or open an existing project.

Step 5: Add the shapefile to a map

ArcGIS Pro: In the Contents pane, right-click on "Map" and select "Add Data." Browse to the location of your folder and add the EPHT geography shapefile to the map.

Step 6: Add the CSV file to the map

ArcGIS Pro: In the Contents pane, right-click on "Map" and select "Add Data." Browse to the location of the CSV file you downloaded from Arizona EPHT Explorer and add it to the map. *Note that CSV files can be added as tables.

Step 7: Check the attribute table of both layers

ArcGIS Pro: Ensure that both the feature class and the CSV file (table) are visible in the Contents pane. Right-click on each layer, select "Open Attribute Table," and verify that the common field “GeogID” exists and contains matching values.

Step 8: Perform the join

Now, we will perform the actual join between the shapefile and the CSV file. The following instructions are for ArcGIS Pro:

1. Right-click on the geography layer (shapefile) in the Contents pane.
2. From the context menu, select "Joins and Relates" > "Add Join."
3. The Join Data dialog box will appear. Choose the following options:
• Join Table: Select the CSV file (table) you want to join with the feature class.
• Input Join Field: Choose the field in the feature class that corresponds to the common field in the CSV file. In this case, choose “GeogID”.
• Join Table Field: Choose the field in the CSV file that corresponds to the common field in the feature class. In this case, choose “GeogID”.
• Enable: ✔️ Keep All Target Features
4. Click "OK" to close the Join Data dialog box.

Step 9: Verify the join

To verify that the join was successful:

1. Open the attribute table of the feature class layer by right-clicking on the layer and selecting "Open Attribute Table."
2. The attribute table should now contain additional fields from the CSV file, indicating that the join was successful.

Step 10: Save the joined data (optional)

If you want to save the joined data as a shapefile, you can export the data:

1. Right-click on the joined layer in the Contents pane.
2. From the context menu, select "Data" > "Export Features."
3. In the Export Features dialog box, choose the location, name, and format for the new feature class.
4. Click "Save" to export the joined data as a new feature class.

That's it! You have successfully performed a join. The resulting attribute table will contain combined information from both datasets, based on the “GeogID” field.