Tahoe-Truckee Cloud Seeding Project

1

DRI Cloud seeding generator: on (Sierra Crest

Water Year 2018

Tahoe Winter Snowfall - 2015-2018 Lake Tahoe Basin Snow Water Equivalent by Water Year

WY2018 74% median

WY2017

WY2016

WY2015

median

Tahoe Winter 2017-2018

Median WY2018(74%) - Nov (11%), (9%) - Dec (25%), (2%) - Jan (31%), (11%) - Feb (24%), (4%) - Mar (9%), (48%)*

* “Miracle March”

Snow Water Equivalent by Month

Tahoe Winter 2017-2018 Temperature Anomalies

Dec 2017 Jan 2018 Feb 2018 Mar 2018

OF

+5oF +8.5oF +2oF +1oF

Lake Tahoe Depth (Tahoe City Gauge)

Natural Rim 6,223’ MSL

Top of dam 6,229’ MSL

Lake Tahoe surface - 122,200 acres

Cloud seeding to increase mountain snowfall over the Tahoe-Truckee Basin

Sierra Crest Carson Range Generator

Clouds colder than -5oC (23F) containing subfreezing water drops

Clouds seeding aerosol - Silver Iodide (AgI)

• Naturally occurring

• Lattice structure similar to ice, creates ice crystals at warmer temperatures

• Safe for the environment

AgI

DRI Remote Controlled Cloud Seeding Generator

Clouds seeding generator - Silver Iodide (AgI)

Fall installation

Tahoe-Truckee Cloud Seeding WY2018 Project Summary

Smaller-scale project for WY 2018 using the unused cloud seeding solution remaining from WY2017. (Cloud seeding project was suspended in early January 2017 due to deep snowpack and forecasts of heavy precipitation). Primary Sponsor – Western Regional Water Commission ($100,000) Additional Sponsor – Mt Rose Ski Resort ($2,500)

WY 2018 Tahoe-Truckee network

10

CSG

Tahoe-Truckee Project WY2018

11

October and November 2017 - All cloud seeding generators were visited. The cloud seeding equipment was tested

and made fully operational, Barker Pass generators reinstalled per USFS permit. - All installed WRWC gauges were visited and serviced for the Water Year

measurements. December 2017 – Began informally watching the weather for seedable storms, Mt Rose joined the program. January – February 2018 – Official 24/7 forecasting and equipment maintenance occurred. - Daily Forecast Discussions - Weekly equipment testing - Field maintenance when required - 24/7 cloud seeding operations when required March 2018 – Official program extended for one month at no additional cost to sponsor April – June 2018 – End of season generator maintenance and equipment removal from field. Data analysis of weather data and seeding operations, equipment reliability, and calculations of cloud seeding SWE increases.

Tahoe-Truckee Project Summary WY2018

12

- 23 cloud seeding events

- 524 total generator hours

Tahoe-Truckee Project Summary WY2018 Cost/Benefit

13

- Calculated additional SWE

(9,628 acre-feet (AF))*

- Cost/benefit $10.65 acre-ft**

• *3.3 billion gallons (if all added to river, enough for ~24,000 Truckee Meadows Households) • ** Seeding solution cost not included in WY2018 project costs

Validation WY2018

• Cloud Seeding operational efficiency (89%) – Winds favorable to

deliver cloud seeding plume into target area

– Temperatures in cloud favorable for successful cloud seeding

– Supercooled (T

WY 2018 Validation Snow

C T C

C

T

Validation Snow Tahoe Winter 2017-2018

Mt Rose SWE (in) 8,800’ MSL

Echo Pk SWE (in) 7,653’ MSL

CSS SWE (in) 6,894’ MSL Truckee2 SWE (in)

6,509’ MSL

March 16.5” March 12.8”

March 14.3” March 8.3”

Target area

Target area Control area

Control area

WRWC Gauge Network

Sierra Nevada

Ruby Mtns

Toiyabe

Tahoe/Truckee

Carson

Walker

Mt Charleston

Tuscarora Mtns.

Humboldt

Santa Rosa Mtns.

WY2019 Nevada State Program

State Funded Portion - Tahoe-Truckee Project WY2018 – Full Program using 3 generators

19

- Purchase consumables 3 gen. (silver iodide, etc.)

- Preseason site visits to fill generators and to make equipment operational

- Install Barker dual generators - Nov 1 – May 15 – 24/7 weather

forecasting/cloud seeding operations - Full time generator maintenance and servicing - Project data analysis, SWE increase estimates,

final report preparation - End of season site takedown - Pull Barker dual generators off site for summer

storage

*Potential for about 11,000 acre-ft SWE on average winter

WRWC Partner with the State Program?

20

- Adopt 2 Tahoe generators - Site preparation - All consumables - Parts (repairs) - Servicing trips - Data

collection/management - Communications - End of season take down.

- $25K per generator

- Potential to increase SWE by

more than 7,000+ acre-ft at cost of $7 acre-ft to WRWC with State Program in place

WY 2018 Tahoe-Truckee network

21

CSG

Budget to operate the Echo and Morattini Flats Generators

22

Cost Category

Echo site

Morattini Flats site

Cloud Seeding Solution (AgI)

$10.500

$10,500

Truck/Snowmobile/Fuel

$1,050

$1,050

Generator Parts (repair)

$1,000

$1,000

Propane/Nitrogen

$1,000

$1,000

Communications /modems

$2,500

$1,500

Site Permits

$500

$500

Total Labor (field/shop)

$8,540

$9,450

====================

==============

=================

Total Costs

$25,000

$25,000

Thank You !

23

Any questions/comments?

Tahoe-Truckee Cloud Seeding ProjectTahoe Winter Snowfall - 2015-2018 Tahoe Winter 2017-2018 Tahoe Winter 2017-2018 Temperature AnomaliesLake Tahoe Depth (Tahoe City Gauge)Cloud seeding to increase mountain snowfall over the Tahoe-Truckee BasinClouds seeding aerosol - Silver Iodide (AgI) Tahoe-Truckee Cloud Seeding WY2018 Project SummaryWY 2018 Tahoe-Truckee networkTahoe-Truckee Project WY2018 Tahoe-Truckee Project Summary WY2018 Tahoe-Truckee Project Summary WY2018�Cost/Benefit Validation WY2018WY 2018 Validation SnowValidation Snow Tahoe Winter 2017-2018 WRWC Gauge NetworkWY2019 Nevada State Program�State Funded Portion - Tahoe-Truckee Project WY2018 – Full Program using 3 generators WRWC Partner with the State Program? WY 2018 Tahoe-Truckee networkBudget to operate the Echo and Morattini Flats Generators Thank You !