2013 update spokane valley-rathdrum prairie aquifer water demand forecast update rob lindsay water...

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2013 UPDATE Spokane Valley-Rathdrum Prairie Aquifer Water Demand Forecast Update Rob Lindsay Water Resources Manager Spokane County Utilities Spokane River Forum Conference March 27, 2013

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2013 UPDATE

Spokane Valley-Rathdrum Prairie AquiferWater Demand Forecast Update

Rob LindsayWater Resources Manager

Spokane County Utilities

Spokane River Forum ConferenceMarch 27, 2013

Spokane Valley-Rathdrum Prairie AquiferWater Demand Forecasts

Presented by:

Mike HermansonWater Resources Specialist

Spokane County Utilities

Spokane River Forum ConferenceMay 23, 2011

Presentation Overview

• Review Spokane County Water Demand Model (2010) and 2012 Updates

• Idaho Future Demand Study• Summary

History

• 2010– Idaho Future Demand Study Draft Results

presentation– Spokane County Water Demand Model presentation

of project goals, objectives, concepts. • 2011

– Spokane County presented results of Water Demand Model, compared two studies

• 2013– Spokane County performed updates to the Water

Demand Model

Background

• Project funded by Washington Dept. of Ecology

• A county-wide, multi-WRIA project• Performed by CDM, supported by

local advisory committee

Background• Evaluations based on:

– Use Sectors (public supply, agricultural, industrial, self supply)

– Geographic Location (SRTC, TAZ)– Population (current census, STRC forecasts)– Variable Weather – Variable Conservation Scenarios– Time

Spokane County Water Demand Model

County Forecast

PublicSupply

Self Supply Residential

Self SupplyIndustry

Agricultural

CommercialIndustrial

UrbanIrrigation

Public-SupplyAgriculture

Single Family

Multi-Family

Non RevenueWater

Residence& Yard

SmallAgriculture

ThermoelectricPower

Golf Courses

Large Industry

Livestock

IrrigatedAcres

• Segregated by Water Use Sector– each subsector has a unique submodel, or way of calculating

water demand

Spokane County Water Demand Model

Total daily water use per single family

residence

Indoor water use

Outdoor water use

Indoor consumptive

use

Indoor non-consumptive

use

Onsite septic

Sanitary sewer

Water use per ft2 of irrigated

landscape

Outdoor consumptive

use

Outdoor non-consumptive

use

% Consumptive area of irrigated landscape

ET RateReturn Flow

• UPDATE - Residential Consumptive/Non Consumptive Segregation

Spokane County Water Demand Model 2010

– 2000 census– 2008 SRTC forecast– 487 separate forecast

units ( aka TAZ; transportation analysis zone)

2012– 2010 census– 2010 SRTC forecast– +/- 500 TAZs

A unique water demand calculation is done for each forecast unit

• Demand from SVRP Aquifer from Spokane CountySpokane County Water Demand ModelSpokane County Water Demand Model

Sector Modeled Reported RPD

Total Production 41,895 41,530 0.88 %

Single Family Residential 15,920 15,617 1.92%

Multi Family Residential 3,996 4,102 -2.62%

Total Residential 19,916 19,719 0.99%

Commercial/Industrial 9,528 9,798 -2.79%

Total Non Residential 10,758 10,118 6.13%

Non Revenue 3,433 3,500 -1.92%

Annual Public Water System Use: Modeled vs. Reported

Reported in millions of gallons per year

Spokane County Water Demand Model

• Monthly Demand from SVRP Aquifer from Spokane County

0

100

200

300

400

500

600

700

2010

2040

CFS(

cubi

c fee

t pje

r sec

ond)

SVRP Aquifer Monthly Water Demand 2010 & 2040

156 CFS difference

Spokane County Water Demand Model

Spokane County Water Demand Model

Year 2008 SRTC Forecast 2010 SRTC Forecast

2010 162,661 157,330

2020 179,812 174,074

2030 199,472 195,845

2040 219,132 207,270

• UPDATE - Comparison of 2008 & 2010 SRTC Forecast of Single Family Dwelling Units

• Conservation and Weather– Conservation efforts can be

masked by changes in weather

Spokane County Water Demand Model

-

5

10

15

20

25

30

35

40

2010 2015 2020 2025 2030 2035 2040

2005 weather

2006 weather 5% conservation

20 year average weather

2006 weatherBillio

ns o

f Gal

lons

per

year

Forecast Year

Comparison of Conservation and Weather on Water Demand

-

5

10

15

20

25

30

35

40

2010 2015 2020 2025 2030 2035 2040

2005 weather

2006 weather 5% conservation

20 year average weather

2006 weatherBillio

ns o

f Gal

lons

per

year

Forecast Year

Comparison of Conservation and Weather on Water Demand

no conservation

no conservation

no conservation

Idaho Future Demand Study• Includes an estimate of current and future use by water use

sector on an annual basis:– Public Water Systems– Self Supplied Domestic– Self Supplied Commercial & Industrial– Agriculture

• Separates Irrigation and Non-Irrigation Use

• Evaluates consumptive vs. non consumptive use

• Range of population & employment growth scenarios

• Detailed analysis of conservation scenarios• Evaluation of potential climate change impacts

Idaho Future Demand Study

• Aquifer Total Demand to 2040– Washington +/- 33 %; Idaho +/- 40%

WA & ID Demand

-

20

40

60

80

100

120

2010 2015 2020 2025 2030 2035 2040

Idaho Demand

Washington Demand

SVRP Aquifer Total Annual Water Demand Projections

Idaho scenario – medium growth & no conservation

Updated Model Applications• Model Applications

– Support local agencies in regional planning/forecasts– Recent updates now support analyses to asses impacts

of inter-basin water transfers, including SVRP to Latah Creek, west plains and the Little Spokane River

– Updates will support and inform the proposed hydrogeologic model development in the Little Spokane River basin

– Evaluates scenarios to assess potential impacts from climate change

Spokane County Water Demand Model

Thank You

Questions?

• Impact of weather on water use

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City of Spokane

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Whitworth Water District

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Spokane County Water Demand Model