By a lot of hard work from the committee and minimal expenditure!
We apply for any sort of grants we can get - e.g. from local businesses and authorities - try and form good relationships with EA, C&RT, FC, ATr, MBRT and UU - in some cases these are the land-owners - and coordinate work parties with them and their schedules. In some cases their gratitude e.g. with Forestry Commission, leads to them paying for stockings, or helping with other items e.g. Tree clearance, Public Liability Insurance.
A lot of local businesses would rather that local youths were fishing local lakes and ponds, rather than bricking windows, etc. This is not meant as a threat to the businesses - pay for our fishing OR we'll brick your windows!
- but is a natural consequence of "idle hands"!
The local Police and PCSOs have been quite supportive by helping-out on bankside tidy-ups, etc.
Also - by having people on the banks - we are quick to spot pollution incidents and report them to the EA, etc - as well as social media. Some companies having been alerted to this are quite responsive and have subsequently shown their gratitude in terms of contributions to stocking funds, etc.
We've also held a few matches through the summer, with the entry fees going into the stocking fund. Some of the lads have got into the Match scene through this - together with help from Seniors on the bank - and even a Teach-in by Ian Heapes (what a nice man!) - No National Champions yet - but who knows?!
No short answer to your question I'm afraid - but you get the idea!