Government Code § 56055

“Member district” means any district which is included, in whole or in part, within another district, a metropolitan water district, or any of the entities enumerated in Section 56036.6, all or any part of the first-mentioned district being entitled, under the provisions of the principal act of the second-mentioned district or entity, to receive or be furnished with any governmental or proprietary service or commodity by the second-mentioned district or entity.