Estero Llano Grande State Park is a state park in Hidalgo County, Texas, United States. The park opened in 2006 and is managed the Texas Parks and Wildlife Department. Estero Llano Grande is a prime spot for birdwatching with more than 350 species documented.
The land where the parks sits was part of the Llano Grande Land Grant granted to Juan José Hinojosa in 1776 by Charles IV of Spain. In early 2000, the state of Texas pieced together the current park from a variety of separate parcels.
The Arroyo Colorado and Llano Grande Lake border the park on the south.