Is Metal Detecting allowed in Louisiana State parks: NO on any archaeological resources. However I do see that you can have a permit around lakes by the US Army Corps of Engineers. See links below.
You can find a link to the Cultural Resources document of the State Parks HERE:
§303. Park Property and Environment
G. No person may excavate, remove, damage, or otherwise alter or deface any archaeological resource located on any park. The display, possession, and/or use of metal detectors or other devices is prohibited. It is strictly forbidden to dig for or otherwise remove any historical feature, relic or artifact. Persons wishing to excavate and remove historical features by professional archaeological means for research purposes must request a permit from the Louisiana Archaeological Survey and Antiquities Commission. Applications for such permits must be made through the assistant secretary, office of state parks.
However, I did find a metal detecting permit application for the US Army Corps of Engineers in Monroe Louisiana HERE:
The permit application from the US Army Corps of Engineers in Monroe Louisiana states: See link above for more details.
The use of metal detectors will be allowed on beaches or other previously disturbed areas that do not contain or would not reasonably be expected to contain archeological, historical, or paleontological resources.
FMDAC Disclaimer: FMDAC assumes no responsibility for any person who knowingly or accidentally violates any state park regulation. Although FMDAC will try to keep this information current we cannot anticipate how each regulation will be interpreted by a specific park department, park employee or other government employee. It is the sole responsibility of each individual to know and obey the regulations of the park or area they are visiting and or metal detecting.