fort phantom

A scalping at Fort Phantom

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Sunset at Lake Fort Phantom

Sunset at Lake Fort Phantom

In my previous posts I mentioned the three reservoirs which supply Abilene’s water, what it takes to fill them up, how that water gets to the lakes, and what happens to that water when we’re finished with it. There is one last source to talk about and that is the Clear Fork of the Brazos River, which is a tributary of the Brazos.

Clear Fork of the Brazos River

As you can see, the Clear Fork of the Brazos passes very close to Fort Phantom Lake, but does not fill it. Wouldn’t it be great for Abilene if it did? Apparently, over 65 years ago, someone thought so, because in 1950 construction began on a diversion dam across the Clear Fork of the Brazos near Fort Phantom Lake. This was nearly 20 years after the dam for the lake was built.

Pumps at the diversion dam “scalp” some of the water from the river and divert it into the lake. Permits dating from 1949 indicate that the City of Abilene was originally authorized to divert 30,000 acre-feet per year. That is approximately 9.7 Billion gallons of water! I reached out to Howdy Wayne Lisenbee, Assistant Director of Water Utilities for the City of Abilene and Mr. Lisenbee confirmed that the city is still permitted up to 30,000 acre-feet per year.

The diversion dam and pump station. Aerial photography courtesy Rocky White

The diversion dam and pump station.
Aerial photography courtesy Rocky White

There are conditions that have to be met before that water is allowed to flow. First, it has to rain on the upstream watershed of the Clear Fork of the Brazos. Once the water is flowing, the city of Abilene is obligated to allow 600 acre feet of water through the dam for downstream users, and must allow some water to flow through the dam while they are pumping. Many Abilene residents show frustration when the City of Abilene does not pump water from the Brazos after a rain, but we are under legal and ethical obligations to let people downstream from us have some of the water.

How does it happen?

When the conditions mentioned earlier are met, water is impounded behind the dam shown in the lefthand side of the above photo. Eight pumps (located on the righthand side of the same photo) push the water a little over 300 yards through a pipeline into Fort Phantom Lake. Of the eight pumps, five are 1,500 horsepower and are capable of moving roughly 100 million gallons per day. the other three, while smaller, are not lightweights: they are 1,000 hp and can pump 50 million gallons of water per day! If all of these pumps were running at the same time it would be possible to fill 984 olympic sized swimming pools in a single day.

Due to permit restrictions and maintenance reasons, usually only a few pumps are utilized at any one time. If during a pumping session one pump were to break pumping could continue with the other pumps. Mr. Lisenbee stated that during the scalping in May the city used a combination of two to four large pumps and a couple of the smaller pumps to add 651 million gallons to Fort Phantom reservoir over the course of three days.

The pipeline which carries water from the Brazos to Fort Phantom Lake

The pipeline which carries water from the Brazos to Fort Phantom Lake

Aerial view of Brazos diversion pipeline. Water flows straight up from this pipe.

Aerial view of Brazos diversion pipeline. Water flows straight up from this pipe.

What is an “acre foot?”

 An acre foot is the amount of water it would take to cover an acre of land (43,560 square feet) with 12 inches of water.

Once the water reaches the end of the pipeline it flows straight up out of the large pipe shown on the right.

This water comes roaring down the into the lake:

The same type of scalping occurs on a smaller scale on the east side of the lake. In 1954 the City of Abilene acquired a permit to divert up to 3,000 acre-feet of water per year from Deadman Creek when conditions allow. In return for this use Abilene is obligated to release a certain amount of treated wastewater back into Deadman creek.

Same as it ever was

This additional water security did not come easily for the citizens of Abilene. Before the Clear Fork of the Brazos diversion dam was even completed landowners downstream began to complain and seek legal action. According to articles from the Abilene Reporter-News from the 1950s, an argument raged between Abilene and the landowners near Albany throughout the ’50s.  These battles echo the new arguments over some of Abilene’s projected water projects.

As the population of the area grows and as climate change continues to alter our landscape, these arguments over water will also continue. In my final article on Abilene water I will explore what the search for new water in the past was like as compared to the searches in our near future.

Not so Waste(ed) Water

/ Rowdy / 2 Comments

[This is part of my continuing series on how Abilene, Texas obtains its water. The series starts here and continues here]

Reusing waste water isn’t a new thing. Several agencies have treated sewer water to use in various ways. For example, both El Paso and San Antonio inject their treated effluent water into the ground to recharge aquifers. In 2001 Abilene completed a pipeline from the sewer treatment plants north of Abilene to Lake Kirby in southern Abilene. This water is used for recreation at the lake and is also used for irrigation for local parks, golf courses, universities, and Dyess Air Force Base.

This past winter an additional pipeline to Fort Phantom Lake was completed, improved treatment facilities installed, and now treated sewer water flows directly into Fort Phantom Lake. As you may have learned in my earlier post, Fort Phantom is one of the main sources of drinking water for Abilene. It sounds gross to some, but in a dry area that is likely to only become more dry as both the populations and the effects of climate change increase, we need to utilize every drop of water as many times as possible.*

Continue reading →

Grab a paddle

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A while back I posted an explanation of where and how much it would need to rain in order to fill up Fort Phantom lake. Not accounting for absorption or detention in ponds and other low lying areas it would take a 2.6 inch rain on the entire watershed to fill up the lake, according to my previous calculations. Well, currently Cedar, Elm and Catclaw creeks are out of their banks in places. The following map shows a few rainfall totals for places in the Fort Phantom watershed

7_7Rain

Without data for the western edge of the watershed, it is impossible for me to offer a good estimate of exactly how much water will flow to Fort Phantom lake; however, judging from how little Lake Abilene has risen, I think it is safe to say that portion of the watershed will not contribute as much water to Fort Phantom as the eastern half. As of today (July 7th) the lake is at 45.3%, but click on the link to see the current lake level. Get ready to see a change in the lake level in as the week goes on! And check back here later this week to read about why it can take so long between a rainfall event and a change in the lake level.

What does it take to fill up a lake?

/ Rowdy / 6 Comments

UPDATE: After reading this post to find out why it seems the lake rises so slowly, check out this post where I discuss the recent rain.

Most of Texas has been in exceptional and extreme drought for the past five years. Now due to  el niño, we are finishing spring with cool, wet weather. For the first time in what seems like forever much of Texas is officially drought-free. In fact, some areas are experiencing severe flooding; however, that is not the complete story. What I would like to do today is discuss the flooding and drought issues here in Texas on a watershed level.

Despite these floods and despite the fact that overall Texas reservoirs are 78% full, many lakes are at less than 50% of capacity. People living in the Rolling Plains and Edwards Plateau ecoregions of Texas are still experiencing drought conditions. I built this map below to give an idea of the land area in Texas suffering from drought conditions and to show the number of lakes that are less than half full.

drought_d

In the areas still in drought above live approximately 3.5 million people and all of the lakes shown are water sources for these people. There are other water sources, some lakes which have received some water, and other areas depend upon aquifers (a nonrenewable source), but these empty lakes remain important.

What does it take to fill up a lake?

When it rains, the water does several things. On pervious surfaces, such as lawns and fields, it soaks into the ground to provide soil moisture needed for plants. If the rate of precipitation is greater than what can be absorbed, or if the rain lands on hard surfaces, it begins to run off. Take a parking lot for example: rain runs off of the parking lot into a drainage ditch (or storm sewer), the ditch runs into a gully, that gully runs into a creek, that creek runs into a river, and that river may run into a lake before it ends at the ocean. Cities will then pump water from the lake, treat it, and then citizens will use that water in their houses.

Every lake has a certain area from which it will collect water. This area is called a watershed. Since most of my readers are from the Abilene area, I will use Lake Fort Phantom as an example. This lake is currently at 37% capacity. The watershed of Fort Phantom is approximately 500 square miles. If this entire area were to receive a 1 inch rain and if it were all run into the lake, it would receive 8.66 BILLION gallons of water! That is enough water to last 26,600 families for a year. This also happens to be roughly the amount of water in Lake Fort Phantom right now, and there are 10 times as many people depending upon that water.

Using the example above it would take 2.6 inches of rain over the entire watershed to completely fill up Lake Fort Phantom. Recently much of the Big Country has received lots of rain; the nearby town of Merkel has received 11 inches of rain in the last six weeks, but as I mentioned above, Lake Fort Phantom is only 37% full.

So, where did the water go?

Examine this map I made of the Fort Phantom watershed:

Phantomshed

The rain has to fall into the red shaded area in order to reach the lake. While the lake has 500 square miles to draw from, in reality that is not a lot of area. Merkel may have received a lot of rain, but that water will end up in the Brazos river and not Lake Fort Phantom. Another issue is that not all the rain that falls in the watershed actually ends up in the lake. As I mentioned before, some water is absorbed, but a sustainable amount of water is also diverted into ponds, ephemeral wetlands, rainwater collection catchments and flood control basins. Once it is in these areas the water is used by many people and animals, and these areas should not be considered a waste of water.

The drought may be over for most of Texas, and in the coming weeks the drought may be over for us on the Rolling Plains, but please keep in mind that it takes rain falling in exact areas to refill our water supplies. Though it may seem like we are receiving a lot (and in some areas too much) water, we should not back away from water conservation efforts. We may have a cool wet summer, but then again, we may not.

It is a long time until September.

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