Although the sewage collection system of the Evergreen Metropolitan District was still functional on Monday morning, it was running at peak levels, according to an EMD status report.
Residents whose homes are connected to the system have been asked to limit water use to avert backups in the overtaxed system, said Gerry Schulte, EMD general manager.
"Since the lines are flooded, people can expect backups," he said. "The main line is flooded."
The drinking water supply is safe, Schulte said. As a precaution, the district has increased the amount of chlorine added to the system. While there may be an odor or taste of chlorine in the water, it is safe for drinking.
There are flooded manholes in the Upper Bear Creek area, which Schulte said need maintenance when the road leading to the area is reopened. The extra water from the flooded manholes is further stressing the system, he said.
Because of high levels of rainfall on Friday, water from Bear Creek was flowing into the a discharge pipe at the disinfection room of the treatment plant, making it inoperable, Schulte added. However, the room has been pumped out, and wastewater disinfection resumed Saturday.
On Monday, the flow in Bear Creek above Evergreen Lake was 1,110 cubic feet per second, an amount substantially above the average flow of 20 cfs that usually occurs this time of year, Schulte said.
The peak flow rate for the creek from Sunday's rainfall was 1,250 cfs at 11 p.m., according to the EMD report published Monday. Streamflows were continuing to decrease Monday.
Schulte said that he wanted to reassure residents about the stability of the Evergreen Lake Dam, which he said was not in danger of failing.
"There's a lot of people who called and were fearful about the dam," he said.
"Evergreen Dam is a solid, concrete dam," Schulte said. "There's just no pressure on it."
The spillway of the dam is 196 feet wide and 6 feet high and can accept a lot of water flow, he said.
"The stream flows over the dam 365 days a year," he remarked.
The dam is designed to withstand a 30-foot wall of water flowing over it in a 500-year flood, Schulte said. It was substantially reinforced in the 1980s, as directed by the Army Corps of Engineers.
"We put in steel cables 20 feet into the bedrock below the dam," which are capable of withstanding 800,000 pounds of pressure, he noted.
While assessing last week's flooding in Evergreen, Schulte said it was a 25-year event, which last occurred in 1965.
Because a "whole heck of a lot of water" was flowing, district staff were working around the clock at the water and wastewater treatment plants, Schulte said.
As of Monday, Evergreen Lake was closed for recreational use because of logs and other debris that was washing down from Upper Bear Creek, he said. Also, the land around the lake was flooded, he added.
With dry weather predicted this week, Schulte is hopeful that the water levels in the creek and the rate of flow will continue to drop.
"We're looking for it to to dry up a bit," he said.
Contact Sandy Barnes at firstname.lastname@example.org or call 303-350-1042.