Wednesday, September 08, 2010 11:34 AM
Sam Chapman
Lake Austin Flooding
Tropical Storm Hermine moved over central Texas and dropped a huge amount of rain last night. The Colorado River at Austin rose around 20 feet overnight because of the massive amount of water flowing into it.
I live in Apache Shores, which is around a mile below Mansfield Dam on Lake Austin. I went to the waterfront park in the neighborhood today and saw what happened as our neighborhood measured around 10 inches of rain just overnight.
There is a small creek that flows down a valley in Apache Shores. It dumps into Lake Austin by the park. A bridge near the park had huge logs jammed against the guard rail. The creek, which normally has less than a foot of water in it, must have come up over 15 feet last night. Considering this little creek drains a valley around a mile long, a huge amount of rain must have fallen in a short amount of time. I saw evidence of water over roads in 4 different places. Large rocks and logs had been washed onto many areas of the streets as well.
The LCRA rain gage at Mansfield measured over 2.25 inches of rain between 11:10 PM and 12:10 AM. That included a 1.13 inch downpour in just 14 minutes. That was a rainfall rate of almost 5 inches per hour. It also recorded almost 3 inches of rain between 12:55 AM and 1:40 AM.
Looking out over what is normally a very blue Lake Austin, all I saw was muddy, brown water and debris. There was a very large white object floating in the water – perhaps a shed from someone’s property. I counted over a dozen large logs and much more smaller debris.
The funny thing was that even in the absence of significant wind, the debris was moving upstream. This tells me that there was still so much water rushing into the lake that even with floodgates open 21 miles downstream, the lake was still filling up.
The following photos will illustrate what I saw today.
This shows the muddiness of the water in Lake Austin after a flood.
Lake Austin flood debris. This clearly shows why the lake is closed to boat traffic for several days after a flood.
This is what Lake Austin normally looks like. I took just a few days ago this on Labor Day.
Apache Shores flood debris. Debris showed that the water was clearly over the road.
Rocks and dirt that washed over the road in Apache Shores.
Update on Christmas Eve: we haven't seen rain since this flood event, but it looks like we will get some today. As a result of the dryness, there are burn bans in most counties.
