Agenda - Council - 07/28/2015 - Laserfiche WebLink

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be a downward trend in per capita water use for the region, though it is not a significant trend in the data at this point. Communities have reported that per capita water use has continued to decline through 2013 and 2014, and that mandatory tiered rate structures that have been implemented over the last couple of years may be the cause. 200 a 180 ma w 160 Si 140 120 N ro 100 • 80 coN60 I! 40 To 20 v 0 1 Twin Cities Region - Municipal Water Use ■ • Per Capita ■■ ■■■■■■■■■■■ ••'••••••• ••••• ■ ■ ■ ■ •• ■ •• ■Average Daily Water Use Per Capita (gpd) ♦Average Winter Water Use Per Capita (gpd) 1985 1990 1995 2000 2005 2010 2015 Figure 4. Historical Per Capita Water Use, 1990 — 2012, Twin Cities Metropolitan Area Public Water Systems Use of Projections The Metropolitan Council is developing these water use projections in support of the update to the regional Master Water Supply Plan, currently in progress. This information will help us to understand the magnitude and distribution of future water use in the region. The projections also serve as an input to our modeling efforts to predict resource constraints under future scenarios. For the purpose of groundwater flow modeling, an average value of water use is appropriate. This is especially true with steady state modeling scenarios, where annual fluctuations in well pumping are not taken into account. For local water system capacity planning, it is important to plan for higher use conditions in order to avoid water shortages. Therefore, the projections presented in the Master Water Supply Plan generally should not be used for local water system capacity planning purposes. Results The results of the water demand projections for each public water supplier, as calculated by the methods described in this memorandum are attached. The overall demand projection for the region is presented in Figure 5. The light blue dashed lines above and below the projection indicate a +1- 20% uncertainty in our projections. The regional groundwater model will be run with a range of conditions to understand the sensitivity of model results to demand projection inaccuracy.