Spokane Valley-Rathdrum Prairie Aquifer Augmentation Study Results Mr. Colt Shelton 1, Mr. Matt McDonald 1, Dr. Michael Barber 2, Dr. Akram Hossain 3, Dr. Cara Poor 1 1 Civil and Environmental Engineering, WSU 2 State of Washington Water Research Center, WSU 3 Environmental Engineering, WSU-Tri Cities May 23,

Presentation Outline Problem Overview Project Objective Study/Project Area Discussion of Results MODFLOW EPANET CE-QUAL-W2 ECONOMIC ANALYSIS Conclusions 2

Problem Overview Declining low flows in late summer and early fall and project regional growth in demand. 3

Use bi-state MODFLOW model to investigate alternatives associated with aquifer storage and natural recovery in the SVRP including examining: 1) raw water source, 2) location of extraction and injection points, 3) pipeline routes, and 4) costs with ultimate goal of increasing low flow river conditions.. Project Objective 4

Project Area 5 Lake Pend Oreille

Raw Water Sources Spokane River Spokane Well Field Lake Pend Oreille Well Field Pend Oreille River 6

MODFLOW ANALYSIS Converted model to Visual MODFLOW Conducted 275 runs to examine: Extraction well location Injection well location Pumping rate Pumping duration Impact on river flows (quantity & timing) 7

Extraction/Diversion Location Spokane River 1.Expensive water treatment needed although pipeline costs were less. Overall, too costly. Lake Pend Oreille well field 1.Realistic costs and water supply Spokane River well field 1.Created too big a “hole” and stole water from river 8

MODFLOW Results 9 Location Starting Month Rate (ft 3 /s) Length of Injection (Months) Peak Monthly Return (ft 3 /s) Peak Monthly % Return Average Yearly Return Max Month2nd Highest3rd Highest NR1Jan %47.35%AugustJulyOctober NR1Feb %51.56%AugustOctoberJuly NR1Mar %47.15%OctoberAugustJuly NR1Apr %46.98%OctoberDecemberAugust NR1May %46.88%DecemberN/A NR1Dec %47.40%JulyAugustMay NR1Jan %47.33%AugustJulyOctober NR1Jan %47.37%August October NR1Jan %47.37%JulyAugustOctober NR1Jan %47.34%JulyAugustOctober NR1Jan %47.32%JulyAugustOctober NR1Jan %48.71%JulyAugustOctober

3 Possible Pipeline Routes – NR, PL, SR 11

Close-up of Routes & Injection Points 12

EPANET Analysis Pipeline and Injection Well Size versus Head Loss 13

PL3 Head versus Size Pipe Diameter (inches) Injection Well Diameter (inches) Flow Rate to PL3 Location (ft 3 /s) , , , , ,

Examined Infiltration v. Injection 15 Used HYDRUS2D/3D Model High Hydraulic Conductivity throughout aquifer  very large surface area required for significant lag  monthly time step in MODFLOW resulted in very

Costs Considered 1.Pumping (Extraction) Costs 2.Pumping (Distribution) Costs 3.Treatment (Spokane Surface Water) 4.Pipeline Costs 5.Well Field Costs 6.O&M Costs Neglected 1. Right-of-way Costs 17

Example of Annual Costs Injection Rate 100 ft 3 /s200 ft 3 /s300 ft 3 /s Scenario Aug Aug, Sep, & Oct Aug Aug, Sep, & Oct Aug Aug, Sep, & Oct LPO-NR May – 1 m 788 $11, $4, $10, $3,616 LPO-NR May – 2 m 1531 $7, $2,496 LPO-NR May – 2 m 1531 $6, $2, $5, $1,969 LPO-NR April – 3 m 2266 $5, $1,846 LPO-NR April – 3 m 2266 $4, $1, $4, $1,473 LPO-NR April – 4 m 2949 $4, $1,481 LPO-NR April – 4 m 2949 $3, $1, $3, $1,175 18

Construction v. O&M Scenario Construction Costs Annual Operation Cost per Extraction Period (days) LPO-NR $70,427,417$5,032,000$5,647,000$6,243,000$6,858,000 LPO-NR $87,630,000$6,733,000$7,985,000$9,197,000$10,449,000 LPO-NR $73,813,000$4,937,000$5,233,000$5,519,000$5,815,000 LPO-NR $166,676,000$13,067,000$15,719,000$18,285,000$20,937,000 LPO-NR $122,041,000$9,099,000$10,557,000$11,967,000$13,425,000 LPO-PL $198,393,000$15,516,000$18,634,000$21,651,000$24,769,000 SR-PL $464,299,000$12,391,000$13,008,000$13,606,000$14,223,000 19

Ancillary Benefits Possible Increased Hydropower Production  5 dams in study area Water Quality Improvement  Lower instream temperatures  Reduced algal growth at Long Lake 20

Ancillary Benefits Dam Scenarios A.1A.2A.3A.4 Upriver 3,9274,0054,0724,139 Upper Falls 2,8033,1303,4553,754 Monroe Street* ,2831,702 Nine Mile 3,6364,1394,5685,009 Long Lake 8,674 9,13010,351 TOTAL Revenue $1,510,000$1,617,000$1,751,000$1,941,000 Incremental power production (MWh) and additional annual hydropower revenue. Power generated only from March 15 to October 31 of 2001 Based on retail energy cost of $0.078/kWh *Potential turbine flow used 21

Ancillary Benefits: CE-QUAL-W2 Methodology  Visual MODFLOW output Pumping/Injection flow rate of 300 cfs Well field: NR5  CE-QUAL-W2 surface water model Ecology’s Scenario A (background inputs) Altered only the groundwater flow files Examined water entering Long Lake 22

Ancillary Benefits Results Changes in stream flow entering Long Lake increase with longer pumping/injection durations –No significant changes in P, N, DO concentrations or temperature** Scenario Average Increase over Scenario A (cfs)First Increase A.125Sept. 21 A.253July 9 A.387June 29 A.4118June 19 Parameter Scenario AA.1A.2A.3A.4 Dissolved Oxygen (mg/L) Phosphorus (mg/L) Nitrogen (mg/L) Temperature ( o C)

A few key final observations : It appears technically feasible to use Lake Pend Oreille water to enhance SVRP and Spokane River It is not viable to extract Spokane River water due to excessive water treatment costs NR and PL lines most promising – others possible Direct injection is preferable to infiltration Cost rather than technical concerns Discussions with stakeholders, exploratory field work, and model refinement is needed Conclusions 24

Report Availability Spokane Regional Ecology Office Spokane Regional Ecology Office –John Covert or Guy Gregory 25

Questions? 26