Operation Pat Maher, Sr. Hydro Operations Engineer 3 Rivers Flow - - PowerPoint PPT Presentation

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Sep 24, 2023 167 likes •400 views

Spokane River and Coeur dAlene Lake Operation Pat Maher, Sr. Hydro Operations Engineer 3 Rivers Flow into the Lake, 1 River Flows Out Post Falls Dam is 9 Miles Down The Spokane River From the Coeur dAlene Lake Outlet Coeur dAlene is a

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Spokane River and Coeur d’Alene Lake Operation

Pat Maher, Sr. Hydro Operations Engineer

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3 Rivers Flow into the Lake, 1 River Flows Out

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Post Falls Dam is 9 Miles Down The Spokane River From the Coeur d’Alene Lake Outlet

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Coeur d’Alene is a Natural Lake, not a Reservoir

Spokane River Cross Section and Channel Depth At Summer Elevation (2128 ft)

10 20 30 40 50 60 70 80 90 100 110 120 130

0.0 3.0 6.0 9.0

Depth (ft)

Cedars Restaurant

Coeur d' Alene

Lake

Harbor Island

120 ft Deep

Distance (mi)

Spokane River

Outlet channel capacity at summer level = 17,500 CFS
Outlet channel capacity at 2131.5 (average high) = 28,500 CFS
Outlet channel capacity at 2122.5 (average low) = 3,950 CFS
Outlet channel capacity at 2121.3 (current elevation) = 2000 CFS

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USGS CDA Lake Elevation Gage Tubbs Hill Spokane River Outlet

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By Ordinance, Boating Below Spokane St. Bridge Prohibited Whenever Spill Gates are Open

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Post Falls HED McGuire USGS Flow Gage

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River Operations Overview

Summer – Avista holds the level of CDA Lake at 2128 for recreation and public use. Because the dam spill gates are closed, the river above the dam looks like a lake. Fall – The Tuesday after labor day Avista starts to let water out of CDA Lake, drawing the lake down about 1 ½ feet per month until the river is in a natural state. Winter - At some point in December or January the outlet restriction at the river outlet becomes the determining factor of how much water will flow down the Spokane River. From then until we close the spill gates in June, the Post Falls dam has little or no effect on river flows or lake levels. Spring- The Spokane river behaves like a river, not a lake, above the dam, until the snow has melted and we start to close spill gates. If the river flows are very high, river elevations will increase.

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SPOKANE = 97% CLARK FORK = 99%

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SPOKANE = 52% CLARK FORK = 74%

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Spokane Weather For April 2016

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Graph showing Max Temperatures for May 2, At Sites over 6000 feet. 66 Degrees will melt some Snow!

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Upper

St. Joe

River Idaho Mont. Border South of Lake Pend Oreille Mount Spokane

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