Climate Change in Washington - Municipal Water Supply

Municipal Water Supply

Seattle's municipal water systems may hit capacity in 2050. In the October 2005, King County Climate Change Conference, a key topic of discussion was municipal water supply. Experts predict shorter winters and longer summers, which potentially can lead to winter flooding and more severe summer droughts. A recent University of Washington study states that the city of Seattle could see a 14% drop in water supply by 2040. This decrease in the water supply would be equivalent to about 170,000 more people moving into the area. Currently the SPU (Seattle Public Utilities) estimates that it will be able to maintain 171 million US gallons (650,000 m3) per day production for the next 50 years and meet demand which is estimated to maintain itself at 130 million US gallons (490,000 m3) as other cities such as Bellevue begin to use their own water supply. However these number fail to take into account the effects of climate change. It is predicted that by 2040 the water levels will actually decrease to 147 million US gallons (560,000 m3) per day.

With a predicted increase in temperature of 3° by 2040, the region's water supply as a whole is expected to decline. Water supplies come from glaciers and mountain snowpack. As temperatures rise, the elevation at which snow normally falls will increase, and there will be less water available during run-off seasons. Winter and early spring will produce more water than late spring flows, which will decrease the amount of available water during the summer. A lack of water will be problematic for both humans and the region's wildlife. This issue is also concerning because as water levels decrease, there is an expected increase in population in the Puget Sound region. The municipal water supply problem will affect different regions differently depending on the amount of public served by them and the amount of water supply that they can tap into. Everett for example, has a population of 100,000 and the Sultan river provides it with a vast amount of water compared to its population, so global warming will have a minimal effect on the supply of water to it.

The Seattle region currently gets the bulk of its water from the Cedar River and Tolt River watersheds. As the effects of global warming cause water levels to decrease in these watersheds, new water sources must be found. One idea proposed by a utility consortium, Cascade Water Alliance, is to use Lake Tapps, located in Pierce County as a new source of drinkable water. The project is projected to cost 450 million dollars and take decades to complete. These reservoirs are very important to the continued stability of the municipal water supply. Reservoirs hold the early spring melt of snow so that in the summer months it can be released when the snow pack is gone. Reservoirs must be made larger to hold more of the early spring runoff. This will cost millions, if not billions, to the states taxpayers. This, however, will only help slightly. It is projected that by the year 2040 snow pack levels that used to dip to a dangerously low level appeared every 50 years will do so every 5. No matter the size of the reservoir, if there is not enough water to fill them then they will be of little help. The other alternative to curtail water usage would be to increase the price the consumer has to pay for the water.