The suddenly unplugged culvert in Fryer Creek near MacArthur Street has opened more than a just a hole under the creek bed.
Neighbors, who awakened on the morning of July 24 to discover the creek level had drastically dropped behind their homes, continue to express dismay over the incident and to revisit long-held concerns about the Sonoma County Water Agency.
A few, including Greg Percival, who lives at Second Street West and MacArthur Street, have even suggested that the water agency may have caused the culvert to become unplugged a few months ago due to drill-work occurring near the hole – located just north of MacArthur Street where it crosses over the creek.
“I would bet that they loosened it,” Percival said.
Bruce Griggs, who lives on MacArthur next to the creek, recalled a moment earlier this year when two environmental engineers knocked on his door to talk about work planned by the water agency, which maintains the creek. They invited him to a community meeting, Griggs said, and spoke of plans for modifying the waterway in case of flood.
Soon after their visit, Griggs said, a machine was seen taking drill samples near where the hole is now. He said he did not know if the two events were related, or whether the workers drilled at the exact spot where the hole opened up.
But two water agency officials said there was no known connection, with Principal Engineer Kent Gylfe saying, “We don’t think that’s what has occurred out there at all.”
In his opinion, as well as that of Jon Niehaus, the agency’s stream maintenance coordinator, the “low-flow culvert” located there – an 18-inch pipe channeling water north-to-south underneath MacArthur – had become plugged by silt several years ago and stopped functioning as it was supposed to.
No one noticed, and during the summer the waters of Fryer Creek grew higher, warmer and more sluggish than engineers had intended. Then last week, late Wednesday night or early Thursday morning, for unknown reasons, the plugged culvert opened up.
“We’re still uncertain why it unclogged,” Gylfe said. “But it is the way that the system originally was designed.”
Gylfe acknowledged that drilling did occur there in late January or early February, as water agency contractors conducted “geotechnical boring” as part of the agency’s City Watersheds Project.
The $4 million proposal includes planned changes to the MacArthur overcrossing – which water agency officials call a “box culvert” – and “as part of that project, our consultants went out … and did one, maybe two drills,” Gylfe said.
At that time, the crew “Brought a drill rig out to drill a hole down” in the creek bed, he said, adding that no more than two drills were conducted, six inches wide and about 30 feet deep.
Gylfe said he could not immediately verify where the holes were drilled – but he emphasized that when it comes to water flow in Fryer Creek, “The way it’s been operating for the last many years is not the way it was designed to function.”