Top – Pump House, lower dam
#2 – Lower lake, shallow from silt
#3 – Outflow from upper lake
#4 – Upper lake
#5 – Fishing on upper lake
Newport Public Works Director Tim Gross had some troubling news for his city councilors today – news that could very dramatically change Newport’s overall method to provide water to the town. In preparation for putting the finishing touches on the new water treatment plant it was learned that its water intake system, as originally planned, won’t work. That’s because the pump house (in the top photo) is built on pilings that are basically sunk in mud, not in bedrock or concrete and therefore cannot support the much larger, heavier pumps required by the new plant.
But it doesn’t stop there.
Gross told the council that the dam was constructed over 50 years ago in a way that would not pass muster today, that is, with much higher dam construction standards. Gross said that the dam is probably in the same condition it was decades ago, but it can’t support the system that the new water treatment plant intake system demands. Gross said he’s not predicting the dam is going to fail anytime soon, but that based on their core drillings, the dam is rather “mushy.” A federal dam inspection team just recently said as much. Gross said he can’t guarantee that the dam wouldn’t fail in a sizeable earthquake.
What to do?
Gross said the engineering company that’s building the water treatment plant is also an internationally renown authority on certain kinds of dams. Gross said HDR will be doing a more detailed analysis on Newport’s lower and upper dams to help him and others present an understandable range of options to the city council; options like fortifying the dam, replacing the dam, removing the dam altogether, among others. Gross said one option could be to remove the dam, drain the lake and rely just on the upper reservoir for the city’s drinking water. Gross said although it would seem that the community couldn’t stand to lose the water from the lower lake, he says the lower lake is so silted-up that there’s nowhere near the water it had back when it was created. He said it’s never been dredged, as far as he knows, because the lake is a “fishing lake.” To dredge a fishing lake runs afoul of Oregon Department of Fish and Wildlife rules and regulations because dredging harms fish habitat.
Fish or drinking water?
Big Creek Reservoirs are rather odd ducks as water sources go because ODFW stocks it with fish and people fish for them. But as drinking water reservoirs go, 99% of them are usually fenced off and protected from contamination, mainly from humans. So there’s some bureaucratic turf issues looming on the horizon, not to mention the wrath of the fishing community.
The long and the short of it, according to Gross, is that he wants to ensure that despite an earthquake, he wants to have the best possible chance to continue to supply water to Newport. He said he can’t do that if the lower dam fails. So he says one option that may rise to the top is to simply drain the bottom lake and lay a pipe the half-mile between the upper lake and the water treatment plant. Gross said the upper dam appears to be a better built structure than the lower one, or at least a better bet during a strong earthquake. But he says, “only after HDR takes a detailed look at both dams will we know enough to consider our options. From there, it’s up to the city council.”
By the way, Gross said that they can erect a temporary feed system from the lower lake (for the time being) into the new water treatment plant quickly enough to bring the new plant on line as scheduled…likely in late January or early February. But the permanent solution is still drifting around out there in the option ether.
The council was hearing much of what you just read here, during the council meeting Monday night.