Where is the divide in the Okefenokee Swamp between the Suwannee and St. Marys River Basins?
Here are some more maps that do not resolve that question.
For better resolution, advice from a qualified hydrologist is needed.
For reaching the likely divide area by water or land, it appears there are no open paths. Which doesn’t mean it can’t be done, just that it would be difficult.
Meanwhile, you can help stop the proposed titanium strip mine far too near the Okefenokee Swamp:
Thanks to Mike Lusk, Manager of the Okefenokee National Wildlife Refuge (ONWR), for sending me the Water Resource Inventory and Assessment: Okefenokee National Wildlife Refuge, USFWS, August 2015.
It contains this interesting map of sub-basins of the Okefenokee Swamp, which shows a small Southeast sub-basin south of Michell Island and Number One Island, and barely including Cross Branch on its west.
It also contains several maps which use the USGS HUC boundaries. Unfortunately, we know the USGS boundary between the Upper Suwannee River HUC 03110201 and the St. Marys River HUC 03070204 is inaccurate, since it includes the Suwannee Canal in the latter, and water flows down that Canal into the Suwannee River.
This map uses HUC10 boundaries: ten-digit detailed Hydrologic Unit Codes (HUCs).
HUC 0307020403 for North Prong St. Marys River includes most of the Southeast Sub-Basin, but does not go as far north on its east side.
That’s about as far as the eye can see in this aerial:
NNE: up St. Marys River to ONWR: Lacys Kountry Store, 2021-01-10, on a Southwings flight for Suwannee Riverkeeper.
There’s a HUC 0307020407 for Cornhouse Creek-Suwannee Canal. The number indicates it is in the St. Marys River Basin, but, as mentioned, the Suwannee Canal actually is in the Suwannee River Basin.
Maybe one way to phrase the question is whether this HUC10 should really be in the Suwannee River Basin. That would require advice from a qualified hydrologist.
On this WWALS map of the Suwannee River Water Trail (SRWT), the HUC boundary between the Suwannee and St. Marys Basins is indicated by shading. The purple line towards the southeast of the Swamp is my attempt to draw where the actual divide may be. It doesn’t really match any of the above, although it’s perhaps closest to the Southeast Sub-Basin.
Perhaps relevant is this map of “Infrastructure affecting water,” which inside the Swamp mostly consists of paddling trails kept cleared, plus the Suwannee River Sill.
Notice the trail extending south from the Suwannee Canal. It goes to Monkey Lake Canoe Shelter. Mike Lusk tells me the trails extending a bit farther south to Gannet Lake and Grand Prairie are open.
W: Monkey Lake Canoe Shelter between struts, on Southwings flight for Suwannee Riverkeeper, 2021-01-10 30.6749830, -82.1998080
The trails are visible from Monkey Lake Canoe Shelter to Monkey Lake in the lower left corner, and to Gannet Lake upwards to the west.
Often keeping an open path like that can encourage water to drain through it. Which, if that is actually happening, might include Gannet Lake and Monkey Lake in the Suwannee River Basin.
But there are no water paths south of Monkey Lake to Number One Island nor south of Gannet Lake to Mitchell Island. He thinks there used to be a trail west to Blackjack Island, but it has grown closed.
Similarly, regarding land passage from Florida north to the islands, Mike Lusk says an old land route to Bugaboo Island has grown closed. That’s quite far north into the center of the Swamp, west of the Suwannee Canal. I’m guessing that used to run from Billys Island, but I don’t know.
Anyway, currently the only ways to reach Blackjack, Number One, or Mitchell Island would seem to involve bushwhacking, whether by water or land.
Number One Island may be visible as the brownish area beyond Coward Lake in this aerial view. If so, Mitchell Island is probably the bigger brownish area beyond that. Monkey Lake is visible towards the upper right.
Determining water flow in an area as flat as that could be interesting.
One more map while we’re at it. This one shows there are many titanium mines on Trail Ridge, but none anywhere near as close to the Okefenokee Swamp as the one proposed by Twin Pines Minerals between Moniac and St. George.
You can help help stop that mine.
-jsq, John S. Quarterman, Suwannee RIVERKEEPER®