AUSTIN (KXAN) — A classic October rainstorm fueled by tropical moisture from Hurricane Otis led to over 8 inches of welcome rainfall in parts of the Hill Country Wednesday night. But with the rain falling on drought-stricken soil, how much of an impact will it make on our lake levels?

Rain totals were as high as 8.34″ on the San Saba/Llano County line, and 7.41″ near Castell in western Llano County. Heavy rain falling in a short period of time briefly boosted the Llano River into a minor flood stage Thursday morning.

All of that water flows from the Llano River into Lake LBJ, which the Lower Colorado River Authority (LCRA) defines as a ‘pass-through lake’, maintaining a relatively stable level. This led the LCRA to open one floodgate partially on Wirtz Dam and two floodgates at downstream Max Starcke Dam. This is dumping more than 100,000 gallons of water per second directly into Lake Travis.

“This is a good slug of water that is going into [Lake] Travis,” hydrologist Dr. Jordan Furnans, vice president of LRE Water, said. “But it’s not going to change [Lake] Travis water levels very much at all.”

Furnans’ data and official lake level projections from the LCRA only forecast a total rise of 1-2 feet on both Lake Travis and Lake Buchanan when all is said and done. Lake Travis is 54 feet lower than its full elevation.

The benefit of the recent rain, however, is that the exceptionally dry soil is now saturated in the Hill Country, so the next round of rainfall will yield more runoff into the rivers and lakes.

“We’ve definitely saturated the sponge,” Furnans said. “The question is, how long between now and the next storm will that sponge stay saturated enough to generate the runoff that we need.”

KXAN asked Furnans how many more rain events like this one it would take to fill the lakes.

“If it happened twice over the next two days, that might do it,” Furnans said. “But if it happens twice over the next two months, that’s not going to come anywhere close. So it really is a timing and frequency question.”

Rains bring optimism to some in Llano County

Residents in Kingsland, Texas, gathered around one of the flooded areas Thursday, where storm water completely engulfed a road. But instead of fearing the rushing water, many marveled at what it could mean for some of the historically low lakes along the Lower Colorado River.

“It’s pretty amazing. We’ve needed it for so long, and it looks great,” one Kingsland resident told KXAN. 

Tim Jones, who has lived in the area for decades, said it is not uncommon for the road – called Slab Road – to flood when there are sizable rains. 

“This happens all of the time – I mean when it rains… It just hasn’t been raining,” Jones said.