Update 2016-03-27: More how to do this.
Update 2016-03-03: Better outline widths and colors.
Update 2016-02-26: Better colors and transparent shaded areas.
Click on this link for an interactive google map of WWALS watersheds.
The images you see here are static screenshots of that google map. Follow the link above for the actual google map.
The watershed outlines are from USDA GDG, https://gdg.sc.egov.usda.gov/, gotten by selecting any state, place Hydrologic, and a numeric HUC code.* I added the separate colors and widths for each watershed.
The watersheds shown are for these Hydrologic Unit Codes (HUCs):
- HUC 03110203: Withlacoochee River
- HUC 03110204: Little River
- HUC 03110202: Alapaha River, including Willacoochee River
- HUC 03110201: Upper Suwannee River
Many other maps are available under Maps on the WWALS website.
Then select under Order Map layers, “8 Digit Watershed Boundary Dataset NRCS Version”. (If you want more precision, select 12 digit, or even more precise numbers.) Click Continue.
Then Select File Format ESRI Shape. And a map projection, probably Geographic NAD83. Then Inclusion Extract, and Delivery Download. Click Continue.
You’ll need to enter an email address and associated parameters. Then click Continue. Finally, click Place Order.
I don’t know any way to select multiple HUCs at the same time. However, you can click on WHERE in the top of the left menu and pick another one to order, until you successively order all the ones you want.
A few minutes later, you’ll get email with where to download your data. Pick up that ZIP file.
You can extract the data from the ZIP file in the usual manner, such as by unzip.
Then you’ll need to convert the shapefile into KML if you want to use it with a google map. For that you’ll need most likely ogr2ogr; follow the link for how.
You can join this fun and work by becoming a WWALS member today!