Laws about swimming in the Isar

I have been eyeing the Isar for the last month or so waiting for the hot summer (okay, the mildly warm) nights ahead. My questions are: 1) Is it clean enough to swim in? 2) I see people in the river fishing (by Muffathalle) even though there are Verbotten signs around, Can you actually get a ticket for swimming-or is it more that it is your fault if you drown?

I've been in it, and I'm not dead yet, or growing any unidentifiable molds on my body, etc. There have been questionable years though so someone should check about this year.

There are often times of year where the bacteria count is high due to run-off. This is usually after periods of heavy rain eg, spring. Normally though, it's fine for swimming. Don't go too near the weirs though. I usually paddle around south of the Mittlerer Ring, towards the zoo. Anything north could get a bit dicey.

http://www.wasserwirtschaftsamt-muenchen.de/app/baden

Not sure how clean it is after this...