This chapter is not intended to apply to Reelfoot Lake or Big Hatchie River and the waters of such lake or river, or to authorize their draining, and this chapter shall not be construed in any way to authorize the draining of such lake or river or its bottom lands; provided, that dredge boats may be permitted to excavate as far north as, but no farther than, what is known as “Three Bridges” in the fifth civil district of Obion County and the fourth civil district of Lake County.