Lake Chelan Operations

Transcription

1 Lake Chelan Operations IPMA Executive Seminar September 17, 2013 Presented by: Janet Jaspers Chelan County PUD Lake Chelan Hydroelectric Project

2 Today s Discussion Chelan PUD Overview Interesting Facts about Lake Chelan Factors Affecting Lake Operations Snowpack Accumulation Forecasting Inflow Modeling Draft and Refill Cycle 2

3 About Chelan PUD Formed in 1936 First electricity delivered 11 years later Governance Services include energy, local water, wastewater and wholesale fiber-optic Operates three hydro projects 1,826 MW of dependable capacity Average Annual generation ~ 9 million MWh More than 48,000 retail electric customers Average retail residential rate second lowest in nation

4 Interesting Facts about Lake Chelan The name Chelan is a Salish Indian word, Tsi Laan, meaning deep water Lake Chelan is more than 51 miles long and almost 1500 feet deep 25 th deepest lake in the world Third deepest in the U.S. (only Crater Lake and Lake Tahoe are deeper) No one had ever swum the length of Lake Chelan until last year (29 year old Emily Von Jentzen did it in 36 hours). 4

5 Interesting Facts about Chelan Hydro Dam construction at Lake Chelan has been a lesson in perseverance. The current dam was constructed between 1926 and The level of Lake Chelan was raised ~21 feet and provided water for real estate, navigation and power generation. 5

6 Interesting Facts about Lake Chelan Hydro A tunnel carries water from the dam to the powerhouse 14 feet in diameter 2.2 miles long Lined with either concrete or steel Carries water for power generation and irrigation Powerhouse contains two generating units that can produce up to 62 MW Empties into the Columbia River at Chelan Falls 6

7 Factors affecting Lake Operations Chelan PUD has a federal license to operate Lake Chelan License contains 7 operating objectives and target lake levels May 1 to Oct 1, including: Maintain minimum flows in the Chelan River* Reduce high flows in the Chelan River* Regulatory flood control requirements* Usable lake levels for recreation * priority over lake levels 7

8 Managing Lake Levels is a Balancing Effort Low Snowpack or Early Runoff Higher Elevation Recreation Dock Access Irrigation/Water Pumps Lower Elevation Minimum Flows* Reduce High Flows* Flood Control* Shoreline Erosion Tributary Barrier Removal Large Snowpack or Late Runoff Water for Summer Power Generation Power Generation 8 * Priority over lake levels as specified in the Comprehensive Settlement Agreement/License

9 Managing Lake Chelan The biggest factor affecting the annual drawdown and refill of Lake Chelan is snowpack accumulation. 9 Stehekin

10 Snowpack Accumulation 10

11 11 Snowpack Monitoring and Survey Lyman Lake

12 12 Black bear activity at Miners Ridge, an abandoned Snotel site

13 Snow Water Equivalent (inch) Lake Chelan Basin Snowpack Corrected for Field Readings Feb 1, Actual Lyman Lake: Elev 5900* Actual Park Cr. Ridge: Elev 4600* Actual Rainy Pass: Elev 4780* Lyman Lake Average Park Creek Average Rainy Pass Average % of Average 90% 83% 93% % avg Updated Feb Date 13

14 Snow Water Equivalent (inch) Lake Chelan Basin Snowpack Corrected for Field Readings Apr 1, Actual Lyman Lake: Elev 5900* Actual Park Cr. Ridge: Elev 4600* Actual Rainy Pass: Elev 4780* Lyman Lake Average Park Creek Average % of Average 111% 110% 129% % avg Updated Apr 1 50 Rainy Pass Average April 1 Runoff Forecast = 116% of avg Date 14

15 Snow Water Equivalent (inch) Lake Chelan Basin Snowpack Corrected for Field Readings May 7, Actual Lyman Lake: Elev 5900* Actual Park Cr. Ridge: Elev 4600* Actual Rainy Pass: Elev 4780* Lyman Lake Average Park Creek Average Rainy Pass Average % of Average 125% 159% 150% % avg Updated May Runoff Forecast = % of avg Date 15

16 Regression analysis is used to develop runoff volume relationships between key variables including Precipitation Snow water equivalent Timing A series of resultant equations is used to help estimate runoff, along with a little gut feeling and a lot of intuition thrown in. 16

17 Why Lake Level Modeling is Important Meet License Requirements Includes Usable Lake Levels for Recreation Efficient Use of District Resources 17 Reasonable Degree of Certainty

18 Lake Elevation in Feet 1101 LAKE CHELAN RESERVOIR Maximum Reservoir Elevation = 1100 Feet May 7, Aug Sep Oct Jul Aug Jun ` New Expected Average Reservoir Elevation Actual Reservoir Elevation May Actual Reservoir Elevation Target Elevations Minimum Reservoir Elevation = 1079 Feet 18

19 Snow Water Equivalent (inch) Lake Chelan Basin Snowpack Corrected for Field Readings Jul 25 Jul 25, 2011 % of Average 80 Actual Lyman Lake: Elev 5900* 1420% Actual Park Cr. Ridge: Elev 4600* 0% Actual Rainy Pass: Elev 4780* Lyman Lake Average Park Creek Average 0% % avg Updated July 25 Lyman Lake Actual SWE 50 Rainy Pass Average Rainy Pass Actual SWE Park Creek Actual SWE 0 Date 19

20 Elevation (feet) Annual Operations Lake Chelan Daily Elevations License Maximum = 1100 feet Aug to Jul License Minimum = 1079 feet 1079 Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Expected Avg w/ New License Minimum Target 20

21 Jan Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec CFS 25,000 Lake Chelan Inflow Daily Traces ,000 15,000 10,000 5, ,000 21

22 Questions? Lake Chelan Lake Levels: 22

23 Questions? Lake Chelan Lake Levels: 23

24 24

25 25

26

27 Lake Level Management Plan Chelan PUD shall make every reasonable effort to comply with the following objectives: 1 Maintain minimum flows in the Chelan River (this objective has priority over lake levels); 2 Reduce high flows in Chelan River (this objective has priority over lake levels); 3 Satisfy regulatory requirements for flood control (adjusting lake level); 4 Provide usable lake levels for recreation (which varies between elevation 1,090 and 1,098 ft, depending on the slope of the shoreline and dock configuration; 5 Reduce shoreline erosion; 6 Prevent fish passage blockages (due to tributary barriers); 7 Minimize effect of refill on attainment of flow objectives for salmon in Columbia River. 27

28 Regression analysis is used to develop runoff volume relationships between key variables including Precipitation Snow water equivalent Timing A series of resultant equations is used to help estimate runoff, along with a little gut feeling and a lot of intuition thrown in. 28