seaplane lake

I was preparing to fly my drone over water today. When I was getting ready to take off, I noticed on the Aloft app that I was near an airplane-shaped chart symbol. I was curious as to what it could be, as it was over the water, and when I zoomed in, it turned out to be a floatplane site. It said...

I'm flying on a lake called Mitchell Lake, it's connected to a bigger lake called Big Lake. There's two seaplanes on the other lake that occasionally land and take off, sometimes on Mitchell Lake but most commonly on Big Lake. I understand I'm supposed to give way to manned aircraft and normally...