Tahoe-Truckee Cloud Seeding Project Water Year 2018 1 DRI Cloud seeding generator: on (Sierra Crest
Tahoe Winter Snowfall - 2015-2018 Lake Tahoe Basin Snow Water Equivalent by Water Year WY2017 WY2016 median WY2018 74% median WY2015
Tahoe Winter 2017-2018 Snow Water Equivalent by Month Median WY2018(74%) - Nov (11%), (9%) - Dec (25%), (2%) - Jan (31%), (11%) - Feb (24%), (4%) - Mar (9%), (48%)* * “Miracle March”
Tahoe Winter 2017-2018 Temperature Anomalies Dec 2017 Feb 2018 Mar 2018 Jan 2018 +2 o F +1 o F +8.5 o F +5 o F O F
Lake Tahoe Depth (Tahoe City Gauge) Top of dam 6,229’ MSL Natural Rim 6,223’ MSL Lake Tahoe surface - 122,200 acres
Cloud seeding to increase mountain snowfall over the Tahoe-Truckee Basin Clouds colder than -5 o C (23F) containing subfreezing water drops Sierra Crest Carson Range Generator
Clouds seeding aerosol - Silver Iodide (AgI) • Naturally occurring • Lattice structure similar to ice, creates ice crystals AgI at warmer temperatures • Safe for the environment
Clouds seeding generator - Silver Iodide (AgI) DRI Remote Controlled Cloud Seeding Generator 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 CSG 10
Tahoe-Truckee Project WY2018 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. 11
Tahoe-Truckee Project Summary WY2018 - 23 cloud seeding events - 524 total generator hours 12
Tahoe-Truckee Project Summary WY2018 Cost/Benefit - 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 13
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<0 o C) liquid water in clouds
WY 2018 Validation Snow T C C T C
Validation Snow Tahoe Winter 2017-2018 Target area Echo Pk SWE (in) Mt Rose SWE (in) Control area 7,653’ MSL 8,800’ MSL March 16.5” March 12.8” CSS SWE (in) Control area Truckee2 SWE (in) Target area 6,894’ MSL 6,509’ MSL March 14.3” March 8.3”
WRWC Gauge Network
WY2019 Nevada State Program Tuscarora Mtns. Santa Rosa Mtns. Ruby Humboldt Mtns Tahoe/Truckee Carson Walker Toiyabe Sierra Nevada Mt Charleston
State Funded Portion - Tahoe-Truckee Project WY2018 – Full Program using 3 generators - 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 19
WRWC Partner with the State Program? - 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 20
WY 2018 Tahoe-Truckee network CSG 21
Budget to operate the Echo and Morattini Flats Generators 22
Thank You ! Any questions/comments? 23
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