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…