Sunday, April 8, 2012

Pressure Grows on Twin Buttes

The Standard Times reported:

The drinking water allowance allocated to the city of San Angelo from the O.H. Ivie Reservoir was cut by 30 percent this month.

San Angelo will need to make up the difference by drawing more from local reservoirs.
That means Twin Buttes.

The San Angelo City Council voted this week to take steps toward pumping water out of the South Pool of the Twin Buttes reservoir and putting it into use since water becomes trapped in the South Pool after it is drawn down past a certain elevation, thereby leaving about a month's worth of water out of reach.
The City plans to pump South Pool water in June, a time of high heat and evaporation.

"Since we'll be relying more on our local sources, to gravity feed down to the water plant, we'll have to start utilizing everything we can from Twin Buttes," said Will Wilde, the city's director of water utilities.

It will gravity feed the water, meaning dry soil and water wicking plants will have their chance to violate the city's assumption:

No water will be lost in the transfer process from the south to north pool..
The City can build a pipeline to Hickory, but can't get South Pool water to the treatment plant without loss?  Something strange is going on.

Councilman Paul Alexander says not to worry about the South Pool:

One medium rain, and that lake (South Pool) will fill up overnight. It takes about 90 days to drain that pool, so we are way behind in schedule. We should be pumping starting April 1st at the latest.
How did last night's rain impact Twin Buttes?  It looked like a medium rain across the Twin Buttes watershed on radar.  This morning's flow looked like:

As for the city's projections on less evaporation, they assume water can be shifted from one pool to the other instantaneously.  They show the South Pool's 520 surface area acres added to the North Pool's 882, bringing the North Pool's surface area to 1093 acres, then show a year's worth of savings.

In reality, that process takes "about 90 days" and will occur during our high evaporation months.  As a result, evaporation savings will be much less than the projected 1622 acre feet.

With our Ivie drinking water down and O.C. Fisher barren, Twin Buttes is it.  .

Update 4-9-12:  Twin Buttes elevation is reported unchanged by the Bureau of Reclamation.  Hopefully, the runoff is upstream, working its way down.


  1. Twin Buttes and O.C Fisher should be used for flood control only. Scalping this much water off the Concho is killing the river. When water is stored in a lake the oxygen levels plummet, the sediment loads are trapped, flood plains become deprived, half of the stream flow is lost from the river basin forever to evaporation, the riparian ecosystem collapses. I think it is pointless to pump the water into the north pool for a few weeks of water, but we wouldn't really be conserving "drinking" water by leaving it in the inaccessible South pool either. I appreciate your love of windsurfing on Twin Buttes, but in the grand scheme of things, this reservoir is environmental catastrophe subsidized by the Bureau of Reclamation. I think we need to reduce the reservoir storage (the two aforementioned lakes which we never actually use except for recreation or irrigation anyway) and save the river. You should check out the books: Cadillac Desert and When the Rivers Run Dry...

  2. I understand the need to pump water from the South Pool in the short term. I don't think it needs to be emptied. Selfishly, the South Pool is the best place to take beginner windsurfers because of the entry slope and prevailing winds blow tired novices back to shore.

    Allie, you raise many good questions. When I lived in Georgia, their lakes were used for flood control and recreation. Thank you for the book references. Do you think pumping the South Pool empty could endanger the South Concho River flow?

  3. i don't know how it would endanger it - it seems if anything it would improve the rate of flow. The volume coming out of the headwaters is not going to change... I was just on the river in Christoval last week thinking how backed up and choked the river even seems there, trying to visualize how the river would have moved naturally through the landscape before all the dams... and trash... lots of trash. It seems like Ivie would make for great windsurfing too?

  4. I'm sure Ivie is great. It's so convenient having local lakes but 10 minutes away. I admit, I've been spoiled. I do like sailing where I have some idea of the bottom structure.

    A good friend windsurfed O.C. Fisher years ago. He was screaming along the surface when his fin caught. It pitched him hard into the water, which less than two feet deep and rocky. He said it hurt like heck.

    I've been lucky to avoid that fate. I did have a fin obliterate on a rocky promotory, just under the surface of the water. Thank heaven, I fell in waist deep water. I flipped over my board to find the fin completely gone. I walked back up the mound. We call that beach "Fin Busters." There are several spots like that at the North Pool.

    I've yet to find anything like that at the South Pool, but maybe pumping will expose things I've yet to see. All the best.