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](https://instantemense.com/wp-content/uploads/2015/05/drought_d.png?w=542&h=693)
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](https://instantemense.com/wp-content/uploads/2015/05/phantomshed1.png?w=676)
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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