County to assist in floodplain situation

by Josh McDonald
Staff Reporter | July 31, 2020 11:50 AM

WALLACE — The Shoshone Board of County Commissioners met with Ben Davis with Alta Engineering to discuss and review Kellogg’s flood mapping contracts.

It was released earlier this month that the U.S. Army Corps of Engineers (USACE) has accumulated data over the years that has the potential to change the floodplain maps on the western end of Shoshone County. Over the years homeowners in Kellogg, Smelterville and Pinehurst have existed within a floodplain as designated by the Federal Emergency Management Agency (FEMA), which in turn has forced them to pay for annual flood insurance on their properties.

The new data from USACE shows that in the event of even the most cataclysmic flood, the channeling that currently exists on the west end of the county would do enough to mitigate potential disaster for homeowners.

To get these new numbers reflected on the maps that FEMA follows and lower the amount of money coming from property owners, they need to be certified and that comes with a price.

According to a recent meeting, that number is somewhere between $30,000 and $40,000.

After discussing the situation with Davis, the commissioners agreed to participate monetarily with an amount to be determined as the BOCC works through the budgeting process.

The BOCC also determined that with their participation in helping the west-end communities, if and when the east-end communities decide that they want to participate in a similar process that they will help.

“We agreed that if they are going to assist the river reach from Elizabeth Park to Pine Creek, they will need to assist with future community flood projects, such as the South Fork of the Coeur d’Alene River from Wallace to Elizabeth Park and Pine Creek through Pinehurst,” said Mike Fitzgerald, BOCC chairman.

The mandatory insurance is rooted directly with flood maps from FEMA, where it shows the possibility for 10-, 50-, 100- and 500-year flood events.

The number of years in flood terms are probabilities. The numbers come from historical data including rainfall and stream stage, and represent the probability of a river hitting flood stage within a certain period of time.

For example, a 100-year flood indicates a flood of a certain magnitude that has a 1 percent chance of happening in any year.

In any given year, a 10-year flood has a 10 in 100 chance of occurring, a 50-year flood has a 1 in 50 chance of occurring, a 100-year flood a 1 in 100 chance and a 500-year flood a 1 in 500 chance.

The current maps used by FEMA in Shoshone County are exceptionally dated and utilize projected river flows in cubic feet per second (CFS), and due to their lack of recent information it shows that the 100- and 500-year flood water flows as potentially disastrous to much of the Kellogg, Smelterville and Pinehurst areas, and thus require flood insurance.

The South Fork of the Coeur d’Alene River flows through much of the Silver Valley before converging with the North Fork just south of the Snake Pit in Enaville.

Beginning near Elizabeth Park, the river moves into a deep channel that runs alongside I-90, until it gets through Kellogg where the river banks level out.