Rathdrum Prairie Future Water Demand Study
Presented by Neeley Miller
Water Resource Planner, Senior
April 22, 2014
IDAHO Water Resource Board
Future Water Demand
• Regional water-demand projected as part of Comprehensive Aquifer Management Plan (CAMP) Process – 50 year planning horizon – Demand projected to evaluate
adequacy of future supply – Evaluate potential impacts of
climate variability and conservation on water demand and supply
RATHDRUM PRAIRIE AQUIFER
WATER DEMAND PROJECTIONS
Prepared for:
Idaho Water Resource Board Idaho Water Center 322 East Front St P.O. Box 83720
Boise, ID 83720.0098
Idaho Department of Water Resources Idaho Water Center 322 East Front St. P.O. Box 83720
Boise, ID 83720.0098
Prepared by:
SPF Water Engineering, LLC 300 East Mallard, Suite 350
Boise, ID 83706
John Church, Idaho Economics P.O. Box 45694
Boise, Idaho 83711
AMEC Earth and Environmental 1002 Walnut Street, Suite 200
Boulder, CO 80302
Taunton Consulting 300 East Mallard, Suite 350
Boise, ID 83706
July 2010
ame
Rathdrum Prairie Aquifer Water-Demand Projection Area
Approach to Projecting Water Demand • Review historic population trends • Estimate current water demand (by sector ~2009) • Review climate projections • Evaluate conservation potential • Project future population and employment growth • Project future water demand
• Developed “water-demand scenarios” to evaluate possible future water-demand outcomes that take into account various population growth rates, levels of water conservation, and the potential impact of climate variability
• Developed water-demand data sets and a forecasting tool (i.e., spreadsheet) for use by IDWR and the IWRB to refine projections as new information becomes available
Review of historic population trends
160,000
County 1970- 1980- 1990- 2000-
134,442 140,000 1980 1990 2000 2007
Growth per decade
I Kootenai 69% 17% 56% 24% 120,000
Bonner 55% 10% 38% 11%
Annual growth 108,685 c 100,000 Kootenai 5.4% 1.6% 4.5% 3.1% 0 ·-.., Bonner 4.5% 1.0% 3.3% 1.6% n,
80,000 -~ C. -<>- Bonner County 0 Q. 60,000 -0-Kootenai County
41,050 40,000
36,835 20,000
24,163 15,667 0
1920 1940 1960 1980 2000 2020
Estimates of current water use (~2009) Sector
Non-irrigation Irrigation Total Use Use (AFA) Use (AFA) (AFA)
Community public water 15,700 18,730 34,430
systems
Self-supplied domestic 2,150 6,650 8,800
Self-supplied commercial 4,220
Assumed 4,220
and industrial negligible
Agriculture Assumed
24,700 24,700 negligble
Estimated total ground 22,070 50,080 72,150
water diversion
Estimated total 3,370 35,060 38,430
consumptive use
ill Excludes an estimated 2,130 AF diverted and re-injected for use in heating and cooling systems. m Consumptive use for non-irrigation is assumed to be 10% for community water systems, 5% for self-supplied domestic, and 40% for self-supplied commercial and industrial. ill Consumptive use for irrigation is assumed to be 70% of total use.
Climate Variability • Water supply and demand are influenced by changes in Climate • Changes in temperature and precipitation are expected to
accelerate from the 20th century trends • More warming in summer than winter • Extreme heat and precipitation events may increase in frequency • Snowpack and precipitation patterns may result in earlier runoff
and more winter precipitation as rain • Summer irrigation requirements may increase:
– Expect up to 6% increase in evapotranspiration per °C increase – Study assumed a 10% increase in future irrigation demand (could range from
5% to 20%)
Water Conservation
1. ~190 gpd/home
2. ~113 gpd/home
3. ~82 gpd/home
The following three future water-demand conditions were used to evaluate potential water savings in the Rathdrum Prairie Aquifer area:
1. No conservation - i.e., no measures or programs are implemented throughout the study period . Continued "status quo" water use was assumed.
2. Intermediate conservation - only voluntary water conservation measures and programs are implemented and continuation of current plumbing codes occurs throughout the study period .
3. Ag1gressive conservation - water conservation progirams are impllemented with government-mandated measures that require maximum efficiency fixtures, appliances and other water saving behaviors (above and beyond current plumbing codes).
Developing Growth Projection Scenarios • External Factors – local policies have limited influence
– Population growth – Economic growth – Climate variability
• Local Factors – local public policy and private incentives can have substantial influence
– Local water-use policy – Water availability – Water conservation
Future Water Demand Scenario Matrix
Low Baseline High Growth Growth Growth
No Scenario Scenario Scenario Conservation 1a 2a 3a
Intermediate Scenario Scenario Scenario Conservation 1b 2b 3b
Aggressive Scenario Scenario Scenario Conservation 1c 2c 3c
Rathdrum Prairie Population Forecast
C: 0 +"' rg -::s C. 0 a. "'C QJ +"' u QJ ·-0 '-a.
700,000
600,000
500,000
400,000
300,000
200,000
100,000
0
-
-[}•High Forecast 580,913 -
-~ Low Forecast ,d,,I -:>-Base Forecast ,
rf 403,391 , , 3.0% JJ
" ,o" -
" .-0 . % ~
~ ,ll -I:!: 285,567 - 6 1.~%
99,185
2000 2010 2020 2030 2040 2050 2060
Rathdrum Prairie Household Forecast 300,000 -----------------
250,000
~ 200,000 -0
.s:::. ~ 150,000 ::J 0 ::c
100,000 -
0
-o-High Forecast
~ Low Forecast
-c-Base Forecast
, ,□'
...,[:],
,rr .J] ,
239,639
, ,
d A
, ,
r1' 166,644
2000 2010 2020 2030 2040 2050 2060
Employment Forecast (baseline – Scenario 2)
+,,I
C (1)
E > 0 C. E w
100,000 ~
90,000
80,000
70,000
60,000
50,000
40,000
30,000
20,000
10,000
0
-+- Manufacturing - ~ Min ing
--a- Construction
~ Transporat ion, Commercia l, & Ut ility
· ~ Wholesa le & Retai l Trade
_. Financial, Insurance, and Rea l Estate
~ Services
- Government
---~---
1960 1980 2000 2020 2040 2060 2080
Population Distribution and Density
LJ Rathdrum Prairie Aquifer Boundary
Housing Units per Acre, 2007
LJ Rathdrum Prairie Aquifer Boundary
Housing Units per Acre, 2030
D 0.000000 - o.◄99999
Future Water Demand 220,000 Conservation Level
3: Low ~ High 200,000 0
-0- lb ~ .c ....J - - la --u-- lc
180,000 -~it
2a ~ 2b -n 2c - - ::::, 0 .c -◊ ... D. ._ Ill
> 0 C) ·-
:.::- 160,000 Q.. :z: ◊ 3a -0- 3b .6. 3c
ro -0J VI
140,000 ::, '-0J ...
120,000 ro 3
"'C 0J 100,000 ... u 0J ·- 80,000 0 ... Q.
60,000
40,000
20,000
2010 2020 2030 2040 2050 2060
Consumptive vs. Non-Consumptive Demand
• Consumptive use: water is lost from hydrologic system – Example: Irrigation, manufacturing
• Non-Consumptive use: water is diverted, used, and returned to hydrologic system
– Example: Indoor domestic use
Projected Consumptive Demand
-'->
200,000
180,000
160,000
':;::. ro 140,000 -a, VI
~ 120,000 a, -n,
~ 100,000 "O a, -~ 80,000 ·o '-~
60,000
40,000
20,000
Conservation Level
::: Low ~ High C 0 o .s:. _, --<>-- la ~~i &. ~To --<>-- 2a 0 C, ·
Q.. X 3a
-0- lb --fr- le
-0- 2b --fr- 2c
-:::r 3b 3c
2010 2020 2030 2040 2050 2060
Future Consumptive Use, Scenario 2b
200,000 I ' 0 Institutional irrigation consumptive use (2b}
I- □ Total self-supplied industrial consumptive use {2b}
- □ Base residentia l in-home consumptive use (2b} ... ~ 150,000
i'a -□ Residential! irrigation consumptiive use (2b}
Commercial, iindustria l, and inst iitutional consumptive use (2b} Q) II') I-
□ Agricultural consumptive use (2b) :::J ... Q) 100,000 ... i'a 3:
"'Cl Q) -u Q) ·-e 50,000 ' 0..
0
2010 2015 2020 2025 2030 2035 2040 2045 2050 2055 2060
Future Water Demand-Water Right Implications • Consumptive use represents the impacts to the aquifer
• Water Rights should provide for total diversion (for consumptive
and non-consumptive use), even though portion of water is returned to the hydrologic system
Impact of Climate Variability, Scenario 2b
• Water Supply Planning should anticipate the impacts of Climate Variability
200,000
~ 150,000 -.!. • 0 :;I .. I -! 100,000
~ • ·e-CL
50,000
0
2000
Water demand, 20% increase in precipitation deficit Water demand, 10% increase in precipitation deficit
-o- Water demand, 5% increase in precipitation defid
- o - Consumptive use, 20% increase in precipitation deficit
- • - Consumptive use, 10% increase in precipitation deficit
- on Consumptive use, 5% increase in precipitation deficit
-•
2010 2020 2030 2040 2050 2060 2070
• Future Demand Study completed in 2010
• Rathdrum Prairie Comprehensive Aquifer Management Plan adopted July 2011
• What next steps were identified in the Rathdrum Prairie Comprehensive Aquifer Management Plan?
• Let’s have a look…
CAMP, Future Water Demand, Next Steps
Rathdrun1 Prairie Aquifer < (,111111·L'ih.'tbl\ l' .\quikr \L111,1gcmc11t J>l:rn
\1.non: Provide a S'Uftainabll! source ofhighqualilJ groundw(l]£T for ciuma and {utur€ eco110mi.c, roc.itrl, andemi.ro11111en1al benefin, tl1l1i preserve the exceptUmill qualil}' ana '<Uabilit)' oftJ,e Rmhdrom P,-airi, Aquifrr.
ldal10 Wah:r Rl",oun.·t.· f·k1,1rd Ju ly 20 11
• Action Item #2 – Establish municipal water rights to ensure that they are available for future needs
• Municipal Water Rights – RAFN?
– RAFN application components • Basic water-right elements • Planning area • Planning horizon • Population projections • Water-demand projections • Review of existing water-rights portfolio
CAMP: Objective #1 Meet Future Demand for Water
Four IWRB CAMP Goals
IMPLEME NTATIO N
ADAPTIVE MANAGEMENT
• Action Item #5 – Assess the Rathdrum Prairie Aquifer Water Demand Projections on a regular
basis
• Compare projections with existing conditions • Review assumptions • Update projections • Are there any missing components? • Different Approach needed?
CAMP: Objective #1 Meet Future Demand for Water
Four IWRB CAMP Goals
IMPLEME NTATIO N
ADAPTIVE MANAGEMENT
Discussion…