A woman walks her dog next to the caution tape which remains where the tree was uprooted.
A woman walks her dog next to the caution tape that blocks off the area where the tree was uprooted. Credit: Bonnie Arbittier / San Antonio Report

A tree that fell onto the River Walk Friday toppled of natural causes after reaching a ripe old age for its species, according to City officials.

By Saturday night, contractors working for the City had removed the tree, which had keeled over a stone wall enclosing a planter bed near the Houston Street Bridge over the San Antonio River. It blocked pedestrian and boat traffic for some time before being removed over the weekend.

City Arborist Mark Bird said in an email that the tree was an Arizona ash, more than 35 years old, and hefty, with a trunk of around 38 inches in diameter.

“Looking at the tree you would not know there were any obvious concerns with the overall health,” Bird said. “The canopy looked full with healthy green leaves and no visible signs of decline or decay on the trunk or limbs.”

Arizona ash are a fast-growing tree species native to parts of the Southwestern U.S. and northern Mexico. They grow fast but die relatively young, with some sources saying they can start to decline as early as 20 years old.

Workers gather to clear the fallen Arizona ash tree from the San Antonio Riverwalk Credit: Courtesy / Jack Ballantyne

Bird attributed the ash’s downfall to its species, age, size, and the small area it was growing in. Recent rains “do not appear to have had any affect on the trees overall health and stability,” he said.

Though it stopped traffic on Friday, the tree’s fall caused no injuries or damage to private property, according to Center City Development and Operations officials.

The ash was a bit player in the full cast of River Walk trees. For most visitors, the towering trees that draw the gaze upwards are bald cypresses, some of them probably hundreds of years old.

Chief among those is Ben Milam bald cypress, also known as the Geronimo tree. According to legend, a Mexican sniper scaled the tree during the Seige of Bexar in 1835 and fatally shot Milam, considered a hero of the Texas Revolution.

Nowadays, roughly 11.5 million people per year are estimated to visit the River Walk, according to a 2014 study. The area presents “unique challenges to tree care professionals,” said Michael Shannon, director of the City’s Development Services Department.

In an email, Shannon said that that contractors regularly maintain trees along the River Walk, pruning them for “for health, aesthetic purposes, and to provide adequate clearances for buildings, bridges, and walkways.”

“Time of day, day of week, time of year, events, and conventions are all considered when scheduling their maintenance,” Shannon said. “We take extra measures to ensure the safety of the public, like securing the pruned limbs with ropes so they are safely lowered to the ground. This also helps in preventing damage to buildings, landscapes, and other structures.”

Brendan Gibbons is a former senior reporter at the San Antonio Report. He is an environmental journalist for Oil & Gas Watch.