A strong and knowledgable field partner is essential to be able to have a succesfull LOCUS program.
It is preferable to build on existing coorporation, if your institute has those. To (re)connect with an existing field partner can safe a lot of time.
If cooperation is not available, consulting public information about programs and entities that operate in the area may provide a useful lead. These may themselves want to be partners or propose other ideas.
It is important to assess to what extent the potential field work partner has the necessary knowledge, local presence and organizational sustainability to function in a partnership