What follows is a response to a posting to the listserve asking for an update on the health of Northwest Pond:
July 8, 2011
lemsgarden [Email address: lemsgarden #AT# gmail.com - replace #AT# with @ ]
Thank you for asking about the update. Below is a statement from Watershed regarding the incident. Aeration pumps would be a terrific and costly solution. (The pumps to meet the need, installation, power source, maintenance etc.) Anyone willing to help with writing up the plan and helping with grant applications, please contact me offlist. (We need the help!) It would be a significant project, and is complicated by the location and configuration of the pond and other environmental factors.
Here is the statement from Watershed Protection:
Between 8 p.m. on July 2 and the morning of July 3, the Watershed Protection Departments Spills Response staff received several calls on their 24-Hour Pollution hotline, 512-974-2550. The calls were reporting dead fish and distressed wildlife at the pond in Northwest District Park. The initial call was from the Texas Commission on Environmental Quality, with subsequent calls from Texas Parks and Wildlife and members of the public.
Staff investigated the complaint and found about 500 dead fish, including about 30 that were more than 12 inches long. The dead fish showed signs that lack of oxygen might be the cause of death. In addition, the water appeared stagnant, and there were no signs of spills or discharges to the pond.
Staff met with Texas Commission on Environmental Quality and Texas Parks and Wildlife Department investigators on the morning of July 3rd. Parks and Wildlife measured the dissolved oxygen in the pond and found it to be low, between 0.4 and 1.4 parts per million. The official conclusion for the mortality was due to a natural drop of the dissolved oxygen influenced by extreme heat, lack of wind, and the large number of fish in the pond. Over the past 10 to 15 years, the Watershed Protection Department has investigated similar incidents at this location, and almost all have been due to the same cause, i.e., weather conditions that promote a dramatic drop in dissolved oxygen levels.
The City of Austins Parks and Recreation Department has removed the dead fish.