Arrowrock, Anderson Ranch and Lucky Peak reservoirs hold a total capacity of about 1 million acre-feet of water for irrigation, recreation and other uses. These reservoirs have two purposes — irrigation storage and flood control. If we didn’t have the reservoirs to store our irrigation water and extend the irrigation season we would quickly run out of irrigation water. The result would be crops, lawns and gardens drying up during the hot summer months. If we didn’t have these reservoirs to assist with flood control, the water would simply roar downriver at uncontrollable levels based on when snowmelt and runoff take place. The result would be catastrophic flooding and serious economic loss to the Treasure Valley and its residents.
A lot more water passes through the Boise River Basin’s reservoirs during years where flood control is necessary. Historically, seven out of every 10 years are years where flood control is needed. As of today, over 600,000 acre-feet of water has already been released for flood control from these reservoirs in a well-calculated manner to protect our residents and to prevent significant flooding of the Treasure Valley.
It is currently estimated that only 25 percent of our total snowpack has melted this year. That leaves close to 2 million acre-feet of additional runoff that has not yet come into the reservoirs to be sent down the Boise River (not including any potential rainstorms that may be in our forecasts). The bottom line — flooding could get a lot worse for Treasure Valley residents as warmer temperatures emerge. The current near-record water flow levels on the Boise River are not only causing flooding, they are responsible for road and Greenbelt closures. They are also costing homeowners and local governments enormous financial losses.
As you watch the historic 2017 high flood flows of the Boise River this spring you need to know that this is water that we are not able to store for future use. This is water going downriver into the ocean never to be seen again. Since the Boise River Basin’s three reservoirs can only store about 25 percent of the total amount of water that fills and passes through them, perhaps it is time to once again address the critical need for additional water storage in the Treasure Valley.
Additional storage is not a new topic and one that really needs more than just a study on — it needs to happen. First of all, additional storage would help prevent flooding of the Treasure Valley, since we would be able to capture more water and allow less to pass through or be released downriver for flood control. Secondly, additional storage would provide more water for urban and rural irrigation uses. As our population expands in the Valley there will be more of a demand for irrigation water from all interests. Lastly, additional storage would provide more opportunity for recreation and wildlife habitat.
Clinton C. Pline is president of Treasure Valley Water Users Association, a regional organization developed to address the need for coordinated collaboration among water delivery entities for the mutual benefit of their respective water users within the Boise River Basin.