Tex. Loc. Gov't Code § 81.026
A county judge or county commissioner may serve on the governing body of or any committee serving an association of counties created or operating pursuant to the provisions of Section 89.002. A county judge or county commissioner may serve as a member of any board of trustees or board of directors or other governing body of any trust or other entity created pursuant to interlocal contract for the purpose of forming or administering any governmental pool, self-insurance pool, insurance pool, or any other fund or joint endeavor created for the benefit of member counties and political subdivisions. In addition, a county judge or county commissioner may serve as a member of the board of directors of any nonprofit corporation that is created and exists solely for the purpose of providing administrative or other services to such trust or other entity. A county judge or county commissioner, acting as a member of any such board or committee, may perform any act necessary or appropriate for the rendition of such service, including the casting of votes and deliberations concerning and execution of contracts or claims with or against any county. A county judge or commissioner may participate in deliberations concerning and cast any vote on any matter before the commissioners court affecting the execution of any contract with or the payment of claims, premiums, dues, or contributions to any such trust, association, nonprofit corporation, or entity or any related matter.
Tex. Loc. Gov't. Code § 81.026