Dike
Dike
Dike, Levee or Dam; whatever you want to call it; it is the Flood Water Barrier that extends 1.6 miles along the south shore of the lake.
The Barrier is made of native peat soils . The channel behind the barrier was the source of the dike material.
The designed top elevation of the floodwater barrier is 2129.0′. This allows for 2 foot of freeboard over 100-year lake elevation of 2127.0′.
Status
The peat material the dike was constructed with has degraded and lowered in elevation in a few locations along the span of the dike, as this material is known to do over time.
When the county was determining how to raise the dike levels back to the original buildout they were told that peat cannot be used for that purpose. Even though that is what the original structure used. In today’s world that material is not allowed.
This brought the NL dike to the attention of Washington State Dam Safety and Natural Resources Conservation Service (NCRS). Who have classified the Newman Lake Peat Dike as a class I Dam.
The solution for bringing the dike levels up to the original has been modeled and discussed multiple times between all agencies and is still ongoing to determine the solution.
The current modeling proposed has a solution to cut a spillway for x many feet, with multiple options within that modeling. Which would still cost a lot of money but not as much as a concrete dam.
Spokane County is currently exploring different funding options to mitigate the economic impact this creates via capital budget requests and grants.
In conclusion, for the moment, nothing has been determined on the solution to bring the peat dike up to it’s original constructed height. It is not a risk in its current condition, all of the modeling is using a 100 year flood that would take 5 days to reach Trent! It is still an ongoing back and forth process between multiple agencies to determine the final solution. This has been going on for years! The community will be notified when something of substance can be brought forward publicly.