One of the Water Division’s responsibilities is providing safe drinking water. In a climate such as ours, you’d think that water would be readily available. However, what you may not realize is that too much rain is a bad thing – in fact, during the fl ood advisories for Sept 6th, Cordova nearly ran out of water!
Huh? Well, when it rains, it provides our three water sources (Orca, Murcheson, & Meals/Heney) ample amounts of water – but that water needs to meet EPA guidelines to be useable. For you scientists, turbidity is one important factor – the measure of relative clarity of a liquid. Controlling turbidity is a required safeguard against pathogens in our drinking water. When it rains hard, sediment is stirred up in our water sources, raising the turbidity beyond safe levels. When that happens, our automatic monitoring systems shut down those water sources and supply residents from our water storage tanks.
That is exactly what happened on the 6th. Working quickly to ensure we had access to safe water, five personnel worked day and night to clean out fi lter baskets and slow the fl ow at our sources as well as manually adjusting chlorine applications to meet disinfection standards associated with the different turbidity levels. If the situation grows beyond the ability of staff to handle, they have to spin up the pumps at the Eyak Filter Plant and switch to Lake water – a costly response due to the electricity needed to power the pumps. Last time the pumps were run, the cost to provide water increased by an average of $10,000 per day! Fortunately, the pumps were not needed this time.
To sum it up, rain is helpful, too much rain is costly.