It is not exactly just an access issue, Pleasant in part of the St Paul water supply chain. Water flows from the Mississippi near Fridley Across town underground and though Charlie, Pleasant etc…. before dumping into Vadnais and down into St Paul from there.
Charles Gilfillan created of the St Paul water company and this water supply system.
https://www.presspubs.com/north_oaks/news/the-gilfillan-north-oaks-years-1878-1883/article_0b013ca8-61d4-11eb-8d83-4370a267eb18.html
Regarding Fishing, it isn’t really just access because it is a water supply. There are strict usage rules that apply, residents can use non motorized boats in it and you can swim in it but they will haul even residents out of there if they are fishing. Trust me I know.
The best way to get a feel for the fish in there is to get connected to local High school kids Instagram accounts…. Thankfully there are still kids sneaking in there and having some fun fishing in very sneaky ways. My barber was in his 70s when he retired, he snuck in there. When he was a kid, I am in my 50’s I snuck in there, my kids the same. All of us got chased out or picked up by the Sheriff at some point. They will take some gear to teach you a lesson.