Third-party testing of the pond in Murphy Park determined a massive fish die-off earlier this month resulted from a drop in dissolved oxygen caused by extreme heat.
In addition, the company hired by the city found no chemicals in the water, according to a social-media post by the Taylor Parks and Recreation Department.
The Facebook notification Tuesday noted that testing found a high level of biological oxygen demand, or BOD, which measures how much oxygen is needed to break down organic matter in the water.
A typical pond has a BOD level of 5 milligrams per liter or less. The Murphy Park pond tested at 35 milligrams per liter.
High BOD levels lowering the amount of oxygen in the water can disrupt aquatic life, officials said.
Common causes include decaying vegetation, warm water temperatures and sediment buildup, according to the post.
According to weather reports, the north Austin area has seen some of the highest summer temperatures ever recorded for September.
Parks and Rec brought in a pond management company to assess the situation.
“Fish kills caused by low dissolved oxygen are common during periods of extreme heat,” Parks & Recreation said in the Facebook post. “As water temperatures rise, the water is able to hold less dissolved oxygen.”
The department said oxygen levels are now returning to normal.
The city department said the water testing was conducted “out of an abundance of caution.”
