Terranate Mud Party preserves piece of Arizona history

In May 2025, the "Mud Party" returned to Presidio Santa Cruz de Terranate, a historic Spanish mission nestled along the San Pedro River within the San Pedro Riparian National Conservation Area near Sierra Vista.

Under the guidance of Bureau of Land Management (BLM) archaeologists Clint Dalton and Ralph Burrillo, along with U.S. Forest Service (USFS) archaeologist Chris Schrager, more than 20 participants came together to apply a fresh layer of mud to the remaining adobe walls. Participants included individuals from the BLM, National Park Service, USFS, Ancestral Lands Conservation Corps, Friends of the San Pedro River, and public volunteers.

This "sacrificial cap" plays a crucial role in protecting the structure, shielding it from erosion caused by wind and rain over the coming months or even years, while ensuring the underlying historic elements remain intact. As the top layer gradually wears away, a new coating is added annually during the Terrenate Mud Party, a tradition that was paused in recent years due to the COVID-19 pandemic.

Originally established in 1775 by Hugo O'Conor, an Irish-born Spanish Army Colonel, the Presidio served as a strategic outpost during conflicts between Spanish forces and Apache groups. However, persistent Apache resistance, corruption within the Spanish administration, and declining morale among soldiers led to the site's incomplete construction. It was ultimately abandoned by 1780, though briefly reoccupied by the U.S. Army about a century later.

Archaeologist Charles DiPeso conducted studies at the site in 1951, suggesting it was built atop the precontact Sobaipuri village of Quiburi. Subsequent research confirmed the presence of an earlier settlement beneath the Presidio that was not the renowned Quiburi villiage, but indicated it was utilized through time by Sobaipuri, Hohokam, and Archaic peoples.

Presidio Santa Cruz de Terranate is the most well-preserved defensive Spanish site among what was once a broader regional network. The mud parties help ensure its longevity, using techniques and materials that closely resemble those employed by the Spanish centuries ago, thereby maintaining the historic authenticity of the site. Sand and dirt for the restoration process were sourced from nearby lands by BLM personnel in the weeks leading up to the event.

Volunteers and partners assist the BLM preserve public lands for present and future generations, helping fulfill essential parts of the BLM's multiple-use, sustained yield mission.

For those interested in participating in the next mud party, contacting the BLM Tucson Field Office or the Friends of the San Pedro River is the best way to get involved.

Ralph Burrillo, Archaeologist