The night of heavy rain that took Salt Creek to within a foot of the levee in some areas and backed water into Lincoln's North and South Bottoms Thursday led to an historic event, the highest crest since 1908.
Official records go back to the 1940s and '50s, and this exceeded anything on the record books, Mayor Chris Beutler said Friday.
The water did not top the levee, but since the stream was full, stormwater from 7 inches of rain Wednesday night could not flow into the creek and backed up into the city, Beutler said.
Salt Creek crested in Lincoln about 6 p.m. Thursday but conditions greatly improved overnight, the mayor said during a Friday morning news conference.
The water had gone down significantly and people who voluntarily evacuated homes Thursday in the North and South Bottoms were told they could go home.
As water continued to rise Thursday, the city had to discharge untreated wastewater from the Teresa Street plant into Salt Creek, an emergency move allowed only if the water is about to damage the infrastructure or send more water into nearby homes, according to Miki Esposito, director of the city’s Public Works and Utilities Department.
The untreated sewage was diluted by the rainwater in the system, but city leaders said no one should play or swim in the creek.
The emergency discharge lasted for about 12 hours Thursday, with about 300 gallons of raw sewage per second going into Salt Creek, said Donna Garden, assistant public works director.
As Thursday wore on, police and fire crews handled 445 total incidents and fire crews, with 107 dispatches, were busy all day and all night, said Public Safety Director Tom Casady.
The city encouraged people, particularly those with mobility issues, to evacuate their homes in the North and South Bottoms as the water continued to rise Thursday afternoon and there was concern it might breach the levees.
Three families from the North and South Bottoms spent Thursday night at the F Street Recreation Center, but most people returned to their homes earlier in the evening.
Water would have spilled quite quickly into those neighborhoods had the levees been breached, Casady said. "You would have gone from being OK in your living room to waist-deep very quickly."
The volume of calls taken by Lincoln Fire and Rescue more than doubled from a normal day. Many were calls to help people whose cars had stalled after they drove into swift-moving floodwater, said Fire Chief John Huff.
In one case, water was up to the steering wheel and the driver panicked, he said.
The good news is that the water is going down and will continue to go down as the system drains itself out, said Glenn Johnson, general manager of the Lower Platte South Natural Resources District.
The Salt Creek flood control system includes lakes upstream like Branched Oak, Wagon Train and Stagecoach that capture the rains first and store water.
In Lincoln, the eight miles of open, wooded floodplain at Wilderness Park acts like a huge sponge that fills up with water.
All of the systems functioned as designed, Johnson said.
Forecasters are calling for some rain Saturday afternoon and evening, but that shouldn't be a concern unless it turns into larger storms than predicted, Johnson said.
The magnitude of the rainfall the region saw Wednesday night – "storm after storm after storm -- was fairly unique," he said.
The NRD has studied the cost-benefit ratio of building in protection for a 100-year storm, rather than the current 50-year flood event, Johnson said.
It would require modifying 20 bridges and the "cost benefit ratio has been 10 cents on the dollar, benefit to cost. Not close to an economic return," he said.
Roads in Lancaster County continued to be inundated, County Engineer Pam Dingman said Friday. Nine roads and bridges were still closed Friday afternoon and will not reopen until county staff can inspect them to make sure they are safe, she said.