The brownish staining is likely from the nasty erosion nutrient fed algae of that color, that now coats all the submerged rocks along the shore here in slime, which makes it near impossible to wade regardless of footwear, and smells truly vile when the Lake recedes and it decays. I cant imagine the extant ecosystem we ‘inherited’ appreciates it much either. It wasnt like that even just a few decades back when we moved here. Real-time human caused erosion impacts are not a hoax.