Meeting Utah’s Future Water Needs January 21, 2016 By Todd Adams and Candice Hasenyager

Overview  Understanding Water Demand  Water Demand Projections Past Current Future

River Basins

Water Suppliers

Utah’s Water Budget

Depletions vs Diversions 200 cfs 100 cfs 80 cfs 180 cfs Diversion Depletion (amount consumed) 20 cfs Return Flow

Use of Diverted Water

Public Community Systems 2010 per Capita Use (gpcd) (Includes Potable and Secondary Water) (105 gpcd) 44% Residential Indoor (60 gpcd) 25% Institutional Outdoor (25 gpcd) 10% Institutional Indoor (5 gpcd) 2% Commercial Outdoor (15 gpcd) 6% Commercial Indoor (25 gpcd) 10% Industrial (5 gpcd) 2% Residential Outdoor (95 gpcd) 40% Outdoor (145 gpcd) 60% Indoor Total Use: 240 gpcd Culinary Use: 185 gpcd Secondary Use: 55 gpcd Utah Division of Water Resources (2014). “Municipal and Industrial Water Supply and Use Study Summary 2010.” Utah Division of Water Resources, Salt Lake City, Utah.

Water Demand

Future Population Projections Utah GOMB 2012 Baseline Projections

Water Resource Models  Wasatch Front Water Demand / Supply Model  Per Capita (GPCD) Model  The future??

Wasatch Front Water Demand/Supply Model  Aimed at modeling 4 counties along the Wasatch Front  Land use model  Forecast demands and supply Water system pressure zone Spatial distribution Demand function Water supply database

Per Capita Model  Models down to potable and secondary  Modeled at the water supplier level but controlled to the basin level  Using the 2010 GPCD as base number  Governor’s population projections  25% conservation by 2025

GPCD Model Pros  Relatively simple approach  Easy to develop  Other states around us have implemented similar models Cons  Use categories were lumped together  Limited scenarios were able to be developed  Modifications to model were painful  “Per Capita Water Use Issue”

Per Capita Water Use Issues Residential Institutional Commercial Total Water Use 180 g/d/h indoor x2/6 360 g/d/h outside x2/6 540 g/d/h Total 10g/d indoor 20g/d outdoor 30g/d/c Total /6 5g/d indoor 1g/d outdoor 6g/d/s Total /6 Per Capita Use 60gpcd 120gpcd 180gpcd 5gpcd 1gpcd Residential Institutional Commercial 540 g/d/h x3/9 30 g/d/c /9 6g/d/s /9 180gpcd 3.3gpcd 0.7gpcd

New Water Demand Model  Project demand by use category to 2060 by water supplier  Scenarios Various population distributions Conservation scenarios based on regional location Use variable changes (e.g., pph, lot size, ET) Climate Cost of water

Indoor Water Use Mayer, P. W., DeOreo, W.B. (1999). “Residential End Uses of Water.” American Water Works Association Research Foundation, Denver, Co.

Utah Division of Water Resources (2009). “2009 Residential Water Use” Utah Division of Water Resources, Salt Lake City, Utah.

Outdoor Water Use Efficiency # of households ASCE (2005). “The ASCE Standardized Reference Evapotranspiration Equation.” American Society of Civil Engineers, Reston, Va.

Commercial, Industrial, Institutional Water Use

Challenges…  Population distributions and projections  Commercial, industrial and institutional water use projections  Current and future water supply  Climate change scenarios Supply Side?? Demand Side??

Lets Put it into Practice…