Water play for a cocker NW of BKK? Where to go please?

We brought our cocker spaniel bitch from the UK last year but have been locked up renovating our first home until now so the poor dog has had little in the way of recreation. We live near Khlong Sam Wa which is located a few miles Northwest of BKK so can easily access Lam Luk Ka and surrounding areas.

Nahkon Nayok is under 2 hours away, Saraburi a little more.

We would like to go with the dog somewhere she can be let off-lead to run and splash in leech-free water, similar to a resort my wife saw on the internet featured in someone's blog, without giving a proper location.

Can anyone advise a place where we can go with our cocker where we can all have a splash, not necessarily deep enough to swim, and where we won't get chased by officialdom for having a dog off-lead. Not too far from a place to park as I cannot walk far.

Thanks all.