[Statesman] Without Rain, There Would Have Been No Ice

Finally we know where the ice came from!

http://www.statesman.com/news/content/news/stories/local/01/20/20rain.html

Without rain, there would have been no ice

Steady showers before freeze nearly forgotten.

By Asher Price
AMERICAN-STATESMAN STAFF
Saturday, January 20, 2007

As this week's ice storm shut down the city, an earlier force of nature was quickly forgotten: the steady, torrential rains that made all that ice possible.

"The flooding has been lost by the ice storm," said Lynne Lightsey, a spokeswoman for the city's watershed protection and development review department.

Because the rainfall was steady but not often hard, there was little movement of sediment. A hose was tangled in a tree on the banks of Shoal Creek near Town Lake, an area that suffered a little damage.

Only two-thirds through the month, this January is already the third-wettest on record, according to monitors at Austin-Bergstrom International Airport. Nearly 7 inches, 6.84 to be exact, have fallen at Bergstrom; normal January rainfall is 2.21 inches.

And you might not want to put away your galoshes and umbrella quite yet. Forecasts call for more rain today.

The rain has come as a relief to the region suffering through a long-term drought. Dry creek beds flowed with water for the first time in more than a year. At Barton Springs, the flow raced from 30 cubic feet per second on Jan. 12 to 90 cubic feet per second on Jan. 13.

"We needed it," said David Johns, an environmental scientist with the city. "We can certainly stand to have more of these sorts of rains as we get further into the year. I like wet years better than dry ones."

Rain has pluses and minuses for water quality. On one hand, it washes dirt and pollutants into creeks and streams that may feed aquifers. On the other hand, the replenished streams and creeks flush out sediment that had accumulated in the aquifer.

The rain has been heavy, but not always hard, which water quality specialists and parks officials credited with keeping the water relatively clean.

"It wasn't a gully-washer," said Kirk Holland, general manager of the Barton Springs/Edwards Aquifer Conservation District. "The rainfall was fairly steady over a fairly long period of time. You just mobilize less sediment and runoff from the lands, especially disturbed lands."

City parks department reports seem to bear that out. The Town Lake hike-and-bike trail and the banks along Shoal Creek and Walnut Creek suffered little damage, and small teams were working to patch up erosion of the hike-and-bike trail, said Victor Ovalle, a spokesman for the city's parks department. (He also said trees toppled over and some water fountains burst in the ensuing ice storm.)

In a standard post-storm procedure, the U.S. Geological Survey took water samples to test for nutrients, chemicals and pesticides, according to Mike Dorsey, a hydrologic technician with the USGS. The analysis, which tests for runoff into the watershed, won't be finished for several weeks.

The big rains have played some havoc with plans by the Lower Colorado River Authority and the City of Austin to lower the level of Lake Austin to give homeowners and businesses a chance to repair their docks and to expose and kill hydrilla and Eurasian watermilfoil, two invasive plants that plague boaters and swimmers.

Mindful of the drought conditions, the LCRA began a conservative drawdown in early January and had planned to lower lake levels 12 feet by mid-February.

The lake level is down less than 3 feet, however, making an effective drawdown iffy, according to Krista Umscheid, a spokeswoman for LCRA. Because of the drought, the river authority is loath to release its newfound rainwater gains, and dock maintenance or plant exposure typically needs at least an 8-foot drop.

asherprice@statesman.com; 445-3643