The council urged the district to take prompt action with the removal process, believing that the sediment accumulation is the cause of rising water levels and poses flooding concerns.

According to Beau Goldie at the water district, the gravel accumulated under the Comer Drive Bridge within the past 14 years is a result of both natural erosion occurring upstream and a backup of sediments caused by the Comer debris basin.

Currently, the bridge is four feet away from flooding. Based on neighbors' observations, the distance between the bottom of the bridge and the creek water used to be 10 feet.

"I used to be able to walk under the bridge," said Marj Ottenburg, a resident on Foothill Lane. "Now I have to crawl on my hands and knees."

Prior to 1992, the district annually removed upstream sediments to stabilize the creek after it constructed the basin and a 12-foot high dam in 1973. The structures were originally designed to capture gravel and debris flowing downstream from the Cocciardi Quarry, which is not in operation now. According to Goldie, the sediments were thought to plug culverts, or drainage pipes, and thereby increase potential for flooding. However, the district ceased maintenance of the basin in 1992 when it discovered that cutting off the supply of upstream sediments caused the creek's bottom below the basin to erode. This occurred because, without gravel to decrease the velocity of the water's flow, water traveled with more force, loosening and capturing nearby objects such as rocks and trees.

The basin, a 20-foot-deep bowl-like structure, and the dam are currently being considered by the water district for possible removal, but they must first undergo a comprehensive study to determine the impacts removing them will have on the creek itself, as well as on abutting properties. The study, which is expected to begin next year, is included in the district's long-term flood-protection program. Goldie said that the public process and actual planning and design phase will not begin until 2014, due to funding.

Residents who are in favor of seeing the dam and basin removed said that the creek would be able to restore itself, although it would never reach the same natural state it was in prior to construction of the basin.

Bob Wallace is one of several residents whose property is directly affected by the structures. He said that the portion of the creek that faces his backyard has lost 3 feet of gravel over the past several years.

Wallace, who takes frequent walks along the creek with his dog, said that the dam and basin are obsolete and should be removed, giving wildlife wider access to go upstream. He added that the gravel should be left behind and redistributed along the creek, not only for aesthetic purposes but for environmental reasons as well. Based on quotes he received from a contractor, he said this option would cost $75,000—$515,000 to $1.1 million less than the district's estimate.

"We need to replenish the creek with gravel and allow Mother Nature to take its course," he said.

John Hulme, another advocate for the removal of the dam, said he is not directly affected by the structure, but is concerned about his neighbor's property, which lost two large oak trees due to the creek's erosion.

"It's very likely that another large oak tree near the dam will be lost if nothing is done in the near future," Hulme said.

Larry Clifford, who lives farther down from Hulme near the dam, said he supports the idea of removing it if the district can ensure that new erosion would not occur. He anticipated that he could lose 20 to 30 feet of embankment if the district does not take preventative measures once the dam is taken out.

According to Goldie and Clifford's analysis, if the dam were removed, water would shoot down from a high elevation and at a high speed, causing part of the embankment to erode and cave in.

"This is exactly what we don't want to happen," Goldie said. "That's why we need to study the issue carefully. We're not exactly sure what the impacts would be to those properties along both ends of the creek."

However, Wallace and Hulme, both former engineers, said they disagree with this theory. Wallace said that instead of the embankment sliding off, sediments collected at the basin would flow down and eventually level out. In the process of leveling out, the velocity of the water would decrease, lowering the potential for the embankment to erode.

Another problem that Goldie cited was urban development. He said that in contrast to natural soil, which allows water to trickle down to the creek at a low velocity, developments such as roads increase the velocity of water going down and contributes to further erosion.

The district is considering four alternatives, mentioned in a feasibility report. Two of the options consist of removing the entire dam and regrading the slope of the channel. Another alternative is to take out the upper level of the dam. Some of the alternatives entail building steps to decrease the velocity of the water.