[kach22i]

Snakes of Louisiana
Snakes of Louisiana | Louisiana Department of Wildlife and Fisheries

Smooth Earth Snake

6-13 inches. Gray, tan, brown or red brown above with tiny black dots on the head; pale yellow to white below; faint pale line may be present down the back; scales smooth or weakly keeled, and in 17 rows.

Or..................

Red-bellied Snake
http://www.wlf.louisiana.gov/serpentes/red-bellied-snake

6-14 inches. Brown or gray above, with two rows of black dots or two or four thin dark lines from head to tail; underside usually red or orange, rarely yellow or dull white; pale spots present on either side of the neck and under each eye; small young have a pale collar; scales keeled and in 15 rows.

Pine Woods Snake
http://www.wlf.louisiana.gov/serpentes/pine-woods-snake

8-15 inches. Reddish brown or tan above, pale yellow below; a distinct dark band passes through the eye, bordered above by a pale line; scales smooth and in 17 rows.

EDIT:

I'm going with the Smooth Earth Snake because of the ridge line on top of the back. The other snakes have no indication of those markings. The one you found it's so pronounced that it could be something not on the two websites I went to.

Louisiana
http://whatsnakeisthat.com/south/louisiana.html?start=40

Common Name Smooth Earth Snake
Scientific Name Virginia valeriae
Total Body Length 39cm
Reproduction Live
Number of Offspring 7
Venom Non-venomous
Distribution MW, S, NE, SE
Notes