Region K has 25 regular members representing many interest groups, including:
- Electric generating utilities.
- Groundwater districts.
- Groundwater management areas.
- Public interest.
- River Authorities.
- Small businesses.
- Small municipalities.
- Water utilities.
There are three non-voting members from Texas Parks and Wildlife Department, Texas Water Development Board and Texas Department of Agriculture.
Member terms are five years. Members may designate an alternate.