Where two or more county sanitation districts have joined in the purchase, ownership, use, construction, maintenance, or operation of a sewerage system or sewage disposal or treatment plant or a refuse transfer or disposal system, or both, either within or without the districts, or have so joined for any combination of these purposes, as provided in Section 4742, and the districts hold their meetings jointly and such meetings are presided over by a director of one of the districts acting as joint chairman for and on behalf of the joint organization, each district so participating may pay the joint chairman the same compensation as a director of such district is

paid.