FISRTLY I WOLD LIKE TO POINT OUT THAT YOU MAYBE BREAKING A BYE LAW BYE SWIMMING IN YOUR LOCAL RIVER,as it may be a protected part of the system, it could be privately owned/council/syndicate/fishery protected,what worked for me was i agreed to do a fish quota check in a south west water river in a limited stretch of water for a limited time only, 2 weeks in total but i could only report on what i saw depending on volume,clarity & time of day, not exactly accurate i know but never the less exciting. ps. have good back up if you drift cos it can be cold,do yourself a recce & make a positive marker for an extraction point