Sunday, March 30, 2014

Pumps to Return to South Pool

Tuesday, April 1st is deja vu time as San Angelo's City Council considers reinstalling Gajeske's pump system to move water from the South Pool at Twin Buttes Reservoir.  The city can pump to the North Pool via the equalization channel or over the dam to the old South Concho River bed which leads directly to Lake Nasworthy.  The three pumps can move 75 acre feet a day with gravity flow through the EQ channel, but only 25 acre feet a day if they go over the dam.

The city council background packet implies the pumping would go South Pool to North, taking only one month to move the South Pool's about 2,700 acre feet (current roughly 2,900 acre feet less the 200 acre feet that pumps can't get).  Then the pumps would be moved to the North Pool to pump that body, currently at about 1,900 acre feet ( and not pumpable using the city's last pumping arrangement).

Dead storage for the North Pool is elevation 1885 feet.  It currently sits at 1882.4 feet. 

This makes moving the water through the Equalization Channel a two stage pumping operation.  Stage one they've done several times, thus city officials have some idea as to the potential impact.  Due to seepage and evaporation losses the combined pools would be about 3,900 acre feet (that's without runoff rains).

The city successfully pumped the North Pool down to 1882 foot elevation, but not lower. After draining the South Pool it will be interesting to see where the City locates the intake piping to tap the remaining water  in the North Pool. They may need a lot of piping.

Of the current 4,900 acre feet, the city will be lucky to get 2,000 acre feet for its municipal water supply when all is said and done.  Lord knows, we need it and more.

Update 3-31-14:  Myself and another windsurfer had fun at the South Pool yesterday.  I was on a 4.5 square meter sail and a 110 liter board.  It was great in the gusts and a bit of work in the lulls.  I was worried about the water temperature, but was find with a warm shirt and convertible wetsuit.  The water was up slightly at 1921.25 feet elevation.   The next month and a half may be prime sailing time, i.e. pre-pumping. 

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