Tulalip Tribes 11/9/2016 - Laserfiche WebLink

TECHNICAL MEMORANDUM (CONTINUED) Based on the above criteria, water projections were generated for 2, 3, 5, and 7 percent annual increases in demand. See ADD projections,Figure 2-2, and MDD projections,Figure 2-3. The 2 percent projection correlates with the population growth estimate made by Snohomish County. The 3 and 5 percent projections reflect a range of actual increased usage in the last 6 years based on TU and QCV meter data. The 7 percent projection is presented to correlate with the steep increase in actual water usage for 2010 to 2012. Once a range of water demand projections was made, an evaluation was done to select the best projection for water system planning. The 2 percent annual increase did not reflect observed water use increases and so it was not selected. The steep increase in demand shown in the 2010 to 2012 data from the 88th Street meter was not considered a likely assumption for long-term projections. This increase was possibly due to a recovery from the 2008 recession and gradual discontinued use of the tribal wells. As an additional evaluation step, the water use data collected from the TU and QCV water meters was trended from 2007 to 2012. Water use for this longer time frame only increased 4 percent per year.This data provided a more plausible basis for future growth projections. Daily Demand at 88 St. Meter 2.5 an E 2 %. a v 0 1/2/2010 7/2/2010 1/2/2011 7/2/2011 1/2/2012 7/2/2012 Month-Year Figure 2-1. Daily Demand at 88th Street Meter The Tulalip Tribes 216-1598-057(01) Tulalip Water Demand Projections Compared to Water Supply 4 August 14,2013 Options