Sandbags aren't being filled yet, but Estes Park is bracing for flooding for the second straight year.With a snow pack more than double an average one, combined with temperatures expected in the 70s for the high country, scientists and town officials are bracing for the spring runoff to ramp up.It looks like we could see some higher flows at the end of the week and over the weekend," said Kate Rusch, public information officer for Estes Park. "So we have to watch it very carefully, which is what we are doing.Nearly a year ago, town officials handed out sandbags. Residents and businesses stacked more than 1,000 of them to keep the overflowing Big Thompson River at bay. The river breached its banks and caused some nuisance flooding last June.Lake Estes acts as a collection point for much of the snow pack melting in neighboring Rocky Mountain National Park. Also part of the Colorado River is also drawn into the lake as part of the Big Thompson project.Kara Lamb with the Bureau of Reclamation said 98 percent of the water in Lake Estes is collected from the Colorado River and sent to the east side of the Continental Divide via the Alva B. Adams Tunnel.Lamb said if runoff gets to be too much, they can close the tunnel to partially regulate how much water Lake Estes collects."We are anticipating we will do that," Lamb said. "There will be enough water coming down that we can do that."Lake Estes can receive up to 550 cubic feet per second from the tunnel. Lamb said to picture how much that is, imagine a basketball court of water every second.Lamb said they can divert some of the water to bypass Lake Estes and head directly to Carter Lake and Horsetooth Reservoir.But despite being able to regulate some of the waterways, there is only so much officials can do."Everybody was projecting an easy runoff last year," Lamb said. "Every year is different. There is a ton of snow up there, and we dont know how it is going to come down."The Big Thompson River runs from Lake Estes downhill toward Loveland and Larimer County and eventually meets up with the South Platte River.