yes there is a fairly good rafting operator with few Australian guides (at least when I went) available at Dandeli. They gave a basic training of rafting and ride was about 9 km among some 6-7 grade II & III rapids. Good fun for first timers. price tag was some 1K odd. I went in April and rafting was only till May. In summers there is too little water while in rainy season there is too much of it making rafting unlikely. Any other time is fine. Overall a nice and calm place to holiday in peace beyond mobile signals!
I went last December. there was a trained group for rafting. I think they operated out of the Kali River Resort (a Karnataka government outfit). They do a fairly good job. Unlike rafting in the Ganga (near Rishikesh), the rapids are more placid and children (but not very small ones) were permitted to go rafting. The location (we were at Hornbill resort) was beautiful, and it was a great vacation