This chapter is applicable to water rights in the Rio Grande Basin below Fort Quitman, and water rights in that portion of the Nueces-Rio Grande Coastal Basin in Starr, Hidalgo, Willacy, and Cameron Counties whose source of water is the Rio Grande, excluding the Pecos and Devils watersheds. All other rules, regulations, or orders promulgated or issued by the commission relating to water rights are also applicable to these water rights unless expressly stated otherwise or in conflict with the provisions of this chapter, in which event this chapter shall govern.