Here are maps of the Suwannee River Basin in the EPA EnviroAtlas, with shadings and boundaries for Hydrologic Unit Codes (HUCs). HUC-8 (eight digits) is big river basins; in this case Little, Withlacoochee, Alapaha, Santa Fe, Upper Suwannee, and Lower Suwannee. HUC-12 is more local.

HUC 8 and 12 150%

What are the odd HUC-12s that are not shaded in? At least some of them, such as around Lake Octahatchee are endorheic basins. ‘An endorheic basin (/ˌɛndoʊˈriː.ɪk/ EN-doh-REE-ik; also endoreic basin and endorreic basin) is a drainage basin that normally retains water and allows no outflow to other external bodies of water (e.g. rivers and oceans); instead, the water drainage flows into permanent and seasonal lakes and swamps that equilibrate through evaporation. Endorheic basins are also called closed basins, terminal basins, and internal drainage systems.”

HUC 8 and 12 100%

Here are the same areas without the HUC shading, making it easier to see the rivers and swamps.

150%

These EPA maps uses the USGS HUC boundaries, which are sometimes incorrect.

100%

The most obvious incorrect boundary in the Suwannee River Basin is in the Okefenokee Swamp, where the Suwannee Canal actually flows into the Suwannee River, and in general, the divide with the St. Marys Basin is farther southeast than USGS shows.

Okefenokee Swamp in the WWALS map of the Suwannee River Water Trail (SRWT)

 -jsq, John S. Quarterman, Suwannee RIVERKEEPER®

You can help with clean, swimmable, fishable, drinkable, water in the 10,000-square-mile Suwannee River Basin in Florida and Georgia by becoming a WWALS member today!
https://wwals.net/donations/

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