Why Rain That Falls In Dallas Provides Drinking Water For Houston

Here’s a startling fact:  Most of the rain that falls in the cities of Dallas and Fort Worth does not provide drinking water for us, instead it provides drinking water to Houston!

The National Weather Service office in Fort Worth put together some great information about the watersheds that feed into the different lakes in North Texas.  The surprising thing is that most of the rain that falls in Dallas and Fort Worth never makes it into the reservoirs that supply water to DFW residents!

Instead, most of the water that falls in the heart of Dallas/Fort Worth flows down the Trinity to Lake Livingston.  Lake Livingston supplies water to Houston and also Polk, San Jacinto, Trinity and Walker Counties.  Below is a map showing the water shed for each lake.  Look at the area shaded in red over Dallas and Tarrant Counties.  Any rain that falls in this area runs all the way down the Trinity to Lake Livingston.

Click on the image to enlarge it.

fig2 Watersheds For DFW Lakes


So where does rain have to fall to fill up the lakes that supply water to the Metroplex.

Below is a map showing a close up view around the Metroplex.  If your city is in an area shaded in blue or purple, the rain you get goes into lakes that provide the water supply.  If you are in the grey area, the water that falls here does not feed into reservoirs that supply water to Metroplex cities.

Click on map to enlarge.

Metroplex where rain falls if it goes into our water areaFINAL


Here is another way to look at the map above.  The two shades of colors on the map represent areas where if rain falls it flows into lakes that comprise the water districts.

Click to enlarge.

lake reservoir water sheds FINAL


So what are the water districts.  Well there are three main water districts that supply water to DFW Metroplex.  Below is a map showing these water districts.  Now this map is different from above.  The different shaded areas represent areas that get water from these districts.  For example, Fort Worth in the green below gets it’s water from the Tarrant Regional Water District.  But again rain that falls in Fort Worth does not feed this water district.  The percentage number on the maps represent the current status full of each water district.


Reservoir Levels


A thank you to the National Weather Service Fort Worth office for some of the images.