The park features a large 4,500-acre (18 km2) reservoir on the Pecos River, created in 1939 by the Sumner Dam of the United States Bureau of Reclamation.

The reservoir is home to various fish species including largemouth bass, catfish, crappie and walleye.

[2] With its campground, expansive views of the sky, and its distance from other cities, Sumner Lake State Park has a low level of light pollution, which makes the state park a great potential place for amateur astronomy.

[3] The park is home to the Sandia hairstreak (Callophrys mcfarlandi), New Mexico's state butterfly.

One-seed juniper, honey mesquite, and spiny cholla dominate the landscape of the park.