Welcome to the pipe hobby.
You might look around for a zipper or fold over tobacco pouch on line or at you local shop that would hold several bowls worth to carry down to the river. Separate pouch for separate blends.
The companies that advertise on the site do carry pouches and there may be...
I started donating regularly every 8 weeks at my work place about 10 years ago and now I am retired so I donate with the city every quarter as my wife works at the local library.
A community service that take about 45 minutes.