September 28, 2022
Watershed Index Online (WSIO) Web Service Guide
1 Introduction
Watershed Index Online (WSIO) is a free, publicly available data library of watershed indicators and a
decision-support tool developed by EPA to assist resource managers, citizens, and other users with
comparing and prioritizing watersheds for restoration and protection. The indicators in the WSIO
measure a wide variety of watershed characteristics (e.g., percent forest cover, number of impaired
waters, or area of protected lands). Indicator data can be accessed by downloading Microsoft Excel or
ESRI geodatabase files from the WSIO website or through the WSIO web service.
Web services provide users with access to data without needing to download and store the dataset on a
laptop or desktop computer. Web services are particularly useful for web-based applications, such as
mapping or data analysis tools. These applications can be programmed to retrieve targeted pieces of a
dataset using web services and then format and display the data according to the needs of users.
The following sections are intended to support users that are interested in accessing watershed
indicator data through the WSIO web service:
• Section 2 - The Basics provides basic information about the WSIO web service.
• Section 3 - Getting Started: Viewing the HUC12 Feature Layer is primarily intended for beginner-
level users of web services and provides step-by-step instructions for viewing maps of indicator data
using ArcGIS Online or ArcGIS Pro software.
• Section 4 - Querying the WSIO Web Service is primarily intended for application developers and
contains examples of how to query the WSIO web service to retrieve indicator data.
2 The Basics
The WSIO web service provides access to a database of indicators for 12-digit Hydrologic Unit (HUC12)
subwatersheds in the contiguous United States. HUC12 boundaries are based on topographic drainage
patterns and are delineated by the US Geological Survey (USGS) and Natural Resources Conservation
Service (NRCS) as part of the national Watershed Boundary Dataset1. HUC12s average approximately 35
square miles in size. The WSIO contains indicator data for 82,915 HUC12s and uses the February 2015
version of HUC12s produced for EPA's EnviroAtlas mapping tool.
The WSIO web service is published as a map service on EPA's ArcGIS Server. The base URL for the WSIO
web service is: https://gispub.epa.gov/arcgis/rest/services/r4/wsio/MapServer. The WSIO web service is
comprised of three items: the HUC12 Feature Layer, the Indicator Data Table, and the Indicator
Information Table. A diagram of these components is provided in Figure 1. Key characteristics of each
item are listed below.
1. HUC12 Feature Layer (https://gispub.epa.gOv/arcgis/rest/services/r4/wsio/MapServer/0)
o Includes polygons depicting HUC12 boundaries and an attribute table that stores indicator
values.
1 Refer to the USGS Watershed Boundary Dataset website for additional background information on HUC12
subwatersheds.
-------
September 28, 2022
o Each row of the attribute table contains indicator values for one HUC12. Different indicators
are stored in the table's columns,
o The layer name is "NHDPIusV2_HUC12" and the coordinate system is WGS 1984 Web
Mercator (Auxiliary Sphere), EPSG code 3857.
2. Indicator Data Table (https://gispub.epa.gOv/arcgis/rest/services/r4/wsio/MapServer/l)
o A standalone table of indicator values for HUC12s.
o Contains the same data as the attribute table of the HUC12 Feature Layer.
o The table name is "lndicator_Data".
3. Indicator Information Table (https://gispub.epa.gOv/arcgis/rest/services/r4/wsio/MapServer/2)
o A table of supplemental information for indicators, including the full name of each indicator,
category, subcategory, and description,
o The "Field_ Name" column contains indicator names exactly as they are stored in the HUC12
Feature Layer and Indicator Data Table. Therefore, the "Field_Name" column can be used to
look up supplemental information for specific indicators of interest,
o The table name is "Indicator Info".
HUC12 Feature Layer (Layer Name = NHDPIusV2_ HUC12) - contains HUC12 polygons and an
attribute table with indicator values for each HUC12
HUC12 TEXT
FOREST_PCT_WS
FOREST_DECIDUOUS_PCT_WS
|
010100020101
77 914245
5.930087
29.810915
010100020102
76.699201
16.125776
22.301464
010100020103
80 407811
10.086189
29.902543
Indicator Data Table (Table Name = lndicator_Data) - contains the same data as the HUC12
Feature Layer attribute table
>
HUC12 TEXT
FOREST_PCT_WS
FOREST_DECIDUOUS_PCT_WS
010100020101
77.914245
5.930087
29.810915
010100020102
76.699201
16.125776
22.301464
010100020103
80.407811
10 086189
29.902543
mninnn?nini
Hi 4141ns
11 n?c.ncu
TRA11917
Indicator Information Table (Table Name = lndicator_lnfo) - contains supplemental information
for indicators
Category Subcategory
Ecological
Ecological
Ecological
Ecological
Forest Cover
Forest Cover
Forest Cover
Forest Cover
Field Name
FOREST PCT WS
FOREST_DECDUOUS_PCT_WS
"FOREST EVERGRN PCT WS
FOREST MIXED
cnncc-T rv-T
p4r_ws
TJ
Indicator Name
% Forest in WS (2016)
% Deciduous Forest in WS (2016)
% Evergreen Forest in WS (2016)
% Mixed Forest in WS (2016)
Description
Percent of the HUC12 cla
Percent of the HUC12 cla
Percent of the HUC12 cla
Percent of the HUC12 cla
-x - x 4- L
Field_Names match the column names of the
HUC12 Feature Layer and Indicator Data Table
Figure 1. Diagram of elements in the WSIO web service.
-------
September 28, 2022
3 Getting Started: Viewing the HUC12 Feature Layer
3.1 Viewing the HUC12 Feature Layer with ArcGIS Online
This section is provided for beginner users of web services that may be interested in viewing the WSIO
indicator data with ArcGIS Online and creating basic maps. Note that the ArcGIS Online Map Viewer
provides limited options to symbolize, filter, or otherwise interact with WSIO indicator data. Desktop GIS
software, such as ArcGIS or QGIS, offers expanded options for creating maps using the WSIO indicator
data. Section 3.2 of this guide describes how to add the HUC12 Feature Layer to ArcGIS Pro software.
3.1.1 How to Open the ArcGIS Online Map Viewer
Click the ArcGIS Online Map Viewer link at the top of the WSIO web service landing page to open the
HUC12 Feature Layer in ArcGIS Online (Figure 2).
4r O https://gispub.epa.gov/arcgis/rest/services/r4/wsio/MapServer
ArcGIS REST Services Directory
Home > services > r4 > wsio (MapServer)
JSON | SOAP
r4/wsio
View In: ArcGIS JavaScriptp^I^nHn^aiwIewe^ArcGIS Earth ArcMap ArcGIS Pro
View Footprint In: ArcGIS Online Map Viewer
Service Description:
Map Name: wsio
Figure 2. Link to the ArcGIS Online Map Viewer on the WSIO web service landing page.
The Contents pane of the Map Viewer displays the HUC12 Feature Layer from the WSIO web service (the
layer name is "NHDPIusV2 HUC12"). The Indicator Information Table and the Indicator Data Table are
also shown in the Contents pane (Figure 3).
^ Q wsio
Q NHDPIusV2 HUC12
~ @ Topographic
IS wsio - Indicator Info
51 wsio - Indicator Data
SI U| | •••
0 A arcgis.com/home/webmap/viewer.html?url=https%3A%2F%2Fgispub.epa.gov%2Farcgis%2Frest%2Fservices%2Fr4%2Fwsio%2FMapServer&source=sd
ArcGIS ^ My Map Open in new Map Viewer Mod
[¥1 Details j aiBasemap | ^ Print| ^ Measure Find address or place
o m i= «
Figure 3. Initial view of the HUC12 Feature Layer in the ArcGIS Online Map Viewer with the Contents
pane highlighted.
-------
September 28, 2022
3.1.2 How to Create an Indicator Map in the ArcGIS Online Map Viewer
The steps below can be used to create a basic map of indicator data within the ArcGIS Online Map
Viewer.
1. In the Contents pane, click on the symboiogy button
for the HUC12 Feature Layer to display the "Change
Style" menu.
2. Use the drop-down menu to pick an indicator of
interest. Note: a description of the available
indicators can be viewed by opening the Indicator
Information Table from the Contents pane.
3. Pick a symboiogy method. The "Counts and
Amounts (Color)" option is recommended.
4. Click the "Options" button to customize the
color scheme and select other display options. Or
skip this step to use the default color scheme.
5. Click "Done" to view a national map of the
selected indicator.
Contents
4 Q wsio
~ NHDP,
UC12
¥ I "•
Change Style
wsio ¦ NHDPIusV2 HUC12
AG CDLNLCD16 PCT WS
Select a drawing style
Set default style
Counts and Amounts (Size)
Location (Single symbol)
¦¦
]QjU
mmmnnz
mm si
Types (Unique symbols)
DONE
CANCEL
-------
September 28, 2022
Figure 4 contains an example map created from the steps described above. The map displays values of
the percent agricultural cover indicator. Refer to the ArcGIS Online help page for style settings for more
information on customizing the display of a map.
Figure 4. Example map of percent agricultural cover in HUC12s created in the ArcGIS Online Map
Viewer with the WSIO web service.
-------
September 28, 2022
3.1.3 How to Filter HUC12s in the ArcGIS Online Map Viewer
The filter option within the ArcGIS Online Map Viewer can be used to display a subset of HUC12s that
meet one or more user-defined selection criteria. To apply a filter, follow the instructions below.
1. In the Contents pane, click the filter button
for the HUC12 Feature Layer to display the
filter menu.
Contents
A ~ wsio
~ NHDPIusV244UC12
11 ' 553
~ ©Topographic
I wsio - Indicator Info
I wsio - Indicator Data
2. The filter menu contains drop-down boxes for creating a filter expression. In this example, the
map will be filtered to only display HUC12s that are located in Arkansas.
In the first drop-down menu, type or select the "STATES2013"column. This column lists the
states that each HUC12 intersects using 2-letter state abbreviations.
3. Select "contains" from the second drop-down box and type "AR" for Arkansas in the third
box.
4. Click the "Apply Filter" button. With these settings, the filter will only display Arkansas
HUC12s on the map by searching for HUC12s that contain "AR" in the "STATES2013" column.
-------
September 28, 2022
Figure 5 contains an example filtered map created from the steps described above. The map displays
values of percent agricultural cover in Arkansas HUC12s, The filter menu can also be applied to only
display HUC12s that meet a numeric expression, such as HUC12s with greater than 25% agricultural
cover. Refer to the ArcGIS Online help page for applying filters for additional details on using the filter
menu.
Flint Hills
Tulsa
Oklahoma City
Dallas
Mississippi
Jackson
Nash
o
Tennes
Birmi
Alabama
1 ""i'i-mJ
Figure 5. Example map of percent agricultural cover in Arkansas HUC12s created in the ArcGIS Online
Map Viewer with the WSIO web service.
-------
September 28, 2022
3.2 Viewing the HUC12 Feature Layer in ArcGIS Pro
ArcGIS Pro software provides users with additional options for creating custom indicator maps. This
section describes steps for adding the WSIO web service to ArcGIS Pro. Depending on internet
connection speed, users may experience long loading times when opening and viewing the HUC12
Feature Layer. In these cases, users may instead download a geodatabase of HUC12 polygons and data
tables from the WSIO website for use in ArcGIS Pro or other GIS software.
In ArcGIS Pro, open the Catalog pane and
select the Project tab. Right-click anywhere
in the grey pane and select "New ArcGIS
Server Connection."
Catalog
Project Portal Favorites
- ? x
SeonrA Project
t> ft Maps
t> @ Toolboxes
t> [gi Databases
t> [§* Styles
t' iS Folders
t> Locators
\m
|©
a
&
>JQ
~~
New Map
New Global Scene
New Local Scene
New Stereo Map
New B a semap
Add Folder Connection
Add Database
New Database Connection
New ArcGIS Server Connection
Add Cloud Storage Connection
New Cloud Storage Connection
Q
IS
{US
In the dialog box, enter the Server URL: https://gispub.epa.gov/arcgis/services and click OK. A
username and password are not required.
Add ArcGIS Server Connection
Server URL:
https://gispub.epa.gov/arcgis/services
Authentication [Optional)
User Name:
Password:
® Save Username / Password to Windows Credential Manager
O Save U semame / Password to connection file
OK
Cancel
-------
September 28, 2022
3. A new "Servers" item will automatically be
added to the Catalog pane. Click the arrow
next to the "services on gispub.epa.gov"
server icon to display a list of folders.
4. Click the arrow next to the "r4" folder to
display a list of map services in the folder.
5. Click the arrow next to the "wsio" service
icon to display a list of layers in the WSIO
web service.
6. Right-click on the "NHDPIusV2_HUC12"
layer and click "Add to Current Map."
Catalog " '
Project Portal Favorites
(y £j Seorch Project P
A il0i Servers
services on gispub.epa.gov.ags
t Hi AgSTAR
t> ii ER_Harvey
t monitor
—~ ' B r4
l> H HCZ
t> ^ RZ
t> j£j WaterMask
I" J ^ W5i0
n lndicator_Data
1111 Indicatorjnfo
NHDPIusV2J-IUC12
+
Add To Current Map
+
Add To New
*
The HUC12 Feature Layer will now appear in the Contents pane and HUC12s will display in the viewer
window. The symbology of HUC12s can be customized to display any indicator and HIJC12s can be
filtered to only display HUC12s that meet user-defined selection criteria. Users can also run
geoprocessing tools on the HUC12 polygons to complete additional analysis.
Contents
ha a /¦
Drawing Order
'f-iMap
- [21 NHDPIusVZ.HUC12
~
[71 Topographic
-------
September 28, 2022
4 Querying the WSIO Web Service
Watershed indicator data can be retrieved by querying the WSIO web service. A query is a string of text
that contains user-supplied search parameters for retrieving data from a dataset. When a web service
receives the query, the data that meet the search parameters are identified and returned to the user.
For example, the HUC12 Feature Layer can be queried to retrieve indicator data for any user-defined
geographic area of interest. The data returned by the query can then be used by application developers
in desktop, mobile, or web-based applications to visualize or analyze HUC12 conditions.
The base URLs for querying the HUC12 Feature Layer, Indicator Data Table, Indicator Information Table
are listed in Table 1. Users of the WSIO web service can develop custom queries to define their desired
outputs and the format of outputs. This section describes commonly used parameters for creating a
custom query and example queries. The ArcGIS reference page for querying a map service contains a full
list of query parameters that are available to map service users and descriptions of each parameter.
The example queries in this section return outputs in "html" format to facilitate viewing in a web
broswer. The output format is specified in the query with the Format parameter (f=html). Readers can
change the Format parameter to view alternative formatting options (for example, f=json will return the
results in JavaScript Object Notation (JSON) format).
Table 1. Base URLs for querying the HUC12 Feature Layer, Indicator Data Table, and Indicator
Information Table.
Item
Base URL
HUC12 Feature Layer
https://gispub.epa.gOv/arcgis/rest/services/r4/wsio/MapServer/0/query
Indicator Data Table
https://gispub.epa.gOv/arcgis/rest/services/r4/wsio/MapServer/l/query
Indicator Information
Table
https://gispub.epa.gOv/arcgis/rest/services/r4/wsio/MapServer/2/querv
-------
DRAFT April 5, 2022
Table 2. Example query parameters for retrieving data from the HUC12 Feature Layer.
Query
Parameter
Description
Example Queries
Where
A clause for filtering the HUC12 Feature
Layer using the layer's attribute table.
Results are returned for any HUC12s that
meet the user-specified criteria.
Query 1. Returns all indicators for a specific HUC12 ID. The HUC12 ID of interest is
020600040203. The query uses the Where parameter and the "HUC12_TEXT" field of the
attribute table to limit the output to the single HUC12 of interest.
https://gispub.epa.gov/arcgis/rest/services/r4/wsio/MapServer/0/querv?where=HUC12 TEXT='
020600040203'&outFields=*&f=html
Input
Geometry &
Geometry
Type
A geographic filter for the query. Results
will only be returned for HUC12s that
meet the geographic filter.
Query 2. Returns all indicators for a HUC12 that intersects a specific point location. The point is
defined using the Input Geometry and Geometry Type parameters. The horizontal (x) coordinate
of the point is -8515000 meters and the vertical (y) coordinate of the point is 4720000 meters.
The geographic coordinates are in the same coordinate system as the HUC12 Feature Layer.
https://gispub.epa.gov/arcgis/rest/services/r4/wsio/MapServer/0/querv?Keometrv=-
8515000,4720000&geometrvTvpe=esriGeometrvPoint&outFields=*&f=html
Query 3. Returns all indicators for HUC12s that intersect a rectangular geographic area of
interest. The rectangular area is defined using the Input Geometry and Geometry Type
parameters. The coordinates of the rectangular area are:
• Minimum horizontal (xmin) coordinate = -8515000 meters
• Minimum vertical (ymin) coordinate = 4720000 meters
• Maximum horizontal (xmax) coordinate = -8510000 meters
• Maximum vertical (ymax) coordinate = 4728000 meters
https://gispub.epa.gov/arcgis/rest/services/r4/wsio/MapServer/0/querv?Keometrv=-
8515000,4720000,-8510000,4728000&geometrvTvpe=
esriGeometrvEnvelope&outFields=*&f=html
Out Fields
A list of fields from the attribute table of
the HUC12 Feature Layer to be included in
the query results. Using an asterisk
(outFields=*) will return all fields.
Query 4. Returns three indicator values for a specific HUC12 ID: the HUC12 name, percent
impervious cover, and percent forest cover in the HUC12. The query uses the Out Fields
parameter to limit the output to the three indicators. The HUC12 ID of interest is
020600040203.
https://gispub.epa.gov/arcgis/rest/services/r4/wsio/MapServer/0/querv?where=HUC12 TEXT='
020600040203'&outFields=NAME HUC12, IMP COV PCT HUC12,FOREST PCT HUC12&f=html
-------
DRAFT April 5, 2022
Table 3. Example query parameters for retrieving data from the Indicator Data Table.
Query
Parameter
Description
Example Queries
Where
A clause for filtering the Indicator Data
Table. Results are returned for any
HUC12s that meet the user-specified
criteria.
Query 5. Returns all indicators for a specific HUC12 ID. The HUC12 ID of interest is
070900020702. The query uses the Where parameter and the "HUC12_TEXT" field to limit the
output to the single HUC12 of interest.
https://gispub.epa.gov/arcgis/rest/services/r4/wsio/MapServer/l/querv?where=HUC12 TEXT=
'070900020702'&outFields=*&f=html
Query 6. Returns all indicators for HUC12s in Wisconsin. The query uses the Where parameter
and the "STATE_MAJ" field to limit the output to HUC12s that have the majority of their area in
Wisconsin.
https://gispub.epa.gov/arcgis/rest/services/r4/wsio/MapServer/l/querv?where=STATE MAJO
RITY='WI'&outFields=*&f=html
Input
Geometry &
Geometry
Type
Not used in queries of the Indicator Data Table. The Indicator Data Table is not linked to HUC12 polygons.
Out Fields
A list of fields from the Indicator Data
Table to be included in the query results.
Using an asterisk (outFields=*) will return
all fields.
Query 7. Returns three indicator values for a specific HUC12 ID: the HUC12 name, the county
where the HUC12 is located, and percent protected lands in the HUC12. The query uses the Out
Fields parameter to limit the output to those three indicators. The HUC12 ID of interest is
070900020702.
https://gispub.epa.gov/arcgis/rest/services/r4/wsio/MapServer/l/auerv?where=HUC12 TEXT=
'070900020702'&outFields=NAME HUC12, COUNTY MAJORITY HUC12,
PROT LAND PCT HUC12&f=html
Query 8. Returns HUC12 IDs in the contiguous US with at least 75% natural land cover. The
query uses the Out Fields parameter to limit the output to the HUC12 ID and percent natural
land cover fields. The Where parameter is used to limit the output to HUC12s with at least 75%
natural land cover.
https://gispub.epa.gov/arcgis/rest/services/r4/wsio/MapServer/l/auerv?where=N INDEX PCT
HUC12>75&outFields=HUC12 TEXT.N INDEX PCT HUC12&f=html
-------
DRAFT April 5, 2022
Table 4. Example query parameters for retrieving data from the Indicator Information Table.
Query
Parameter
Description
Example Queries
Where
A clause for filtering the Indicator
Information Table. Results are returned
for any indicators that meet the user-
specified criteria.
Query 9. Returns the entire Indicator Information Table. The query uses the Where parameter
and the "OBJECTID" field to return all rows.
https://gispub.epa.gov/arcgis/rest/services/r4/wsio/MapServer/2/querv?where=OBJECTID>0&
outFields=*&f=html
Query 10. Returns all columns for a specific indicator of interest: road density in the HUC12.
The query uses the Where parameter and the "Field_Name" column to limit the output to the
road density indicator.
https://gispub.epa.gov/arcgis/rest/services/r4/wsio/MapServer/2/querv?where=Field Name='
ROADS ALL DENSITY HUC12'&outFields=*&f=html
Query 11. Returns all columns for indicators in the "Ecological" category. The query uses the
Where parameter and the "Category" column to limit the output to Ecological indicators.
https://gispub.epa.gov/arcgis/rest/services/r4/wsio/MapServer/2/querv?where=CATEGORY='E
cological'&outFields=*&f=html
Input
Geometry &
Geometry
Type
Not used in queries of the Indicator Information Table. The Indicator Information Table is not linked to HUC12 polygons.
Out Fields
A list of fields from the Indicator
Information Table to be included in the
query results. Using an asterisk
(outFields=*) will return all fields.
Query 12. Returns indicator names and descriptions for all indicators. The query uses the Out
Fields parameter to limit the output to the name and description fields.
https://gispub.epa.gov/arcgis/rest/services/r4/wsio/MapServer/2/querv?where=OBJECTID>0&
outFields=lndicator Name,Description&f=html
Query 13. Returns indicator names and descriptions for indicators in the "Forest Cover"
subcategory. The query uses the Out Fields parameter to limit the output to the name and
description fields. The Where parameter is used to limit the output to indicators in the Forest
Cover subcategory.
https://gispub.epa.gov/arcgis/rest/services/r4/wsio/MapServer/2/querv?where=SUBCATEGOR
Y='Forest Cover'&outFields=lndicator Name,Description&f=html
------- |