The Elm Fork of the Trinity River is the main river east of Denton.  It has been a primary water source for drinking, irrigation, and recreation for all civilizations who have ever lived in the area.  (Yep, it is that important).

It is one of five branches which come together to form the Trinity River while in route down to the Gulf of Mexico.​  
 

Origin Story

Water runoff, natural springs, and other whatnot come together in the watershed south of Saint Jo to form the Elm Fork.  

Prior to the creation of the area Trinity River Basin Lakes, residents routinely saw water feasts or famines. 

Summers were typically oh so long and dry.   Water often became scarce.  And what was available was not nearly enough to accommodate the needs of farmers and other area residents.  

All of the rain came in the Springtime.   And with nothing to hold back the water, it routinely just flowed away, jumping the river and creek banks sweeping away anything in it's path on it's way out of town.  One of most damaging Trinity River floods on record occurred just downstream in Dallas, killing 11 people, leaving 4,000 homeless, and causing $5 million dollars of damage in 1908.  When adjusted for inflation, this would be $119.7 million in 2010 dollars. 

But this ongoing problem was also not unique to North Texas​.  Once leaving Denton, Trinity River flood waters must flow another 691+/- winding miles through central Texas before reaching a wide open Gulf of Mexico.  As such, it was quickly determined any solution would require both long term planning and incur significant cost to complete.  The end result was a decision to build a complex system of man-made lakes along the Trinity River and it's tributaries.  These lakes would be designed for two key purposes: flood control and long term water sources.

By 1927, Lake Dallas was built southeast of Denton by the W.E. Callahan Construction Company.   This was later expanded into Lake Lewisville after the US Army Corps of Engineers completed the new dam farther downstream in by the end of 1954.  The Corps later completed Lake Ray Roberts in 1986.

With the Lake construction complete, flooding along the Elm Fork of the Trinity River has been routinely minimized when the storms come through.  The Lakes catch and retain overflow water from the floodplain long before it reaches downstream populated areas.  This captured water is either retained long term or released at a later date in a controlled manor.  

The Cities of Denton and Dallas jointly own water rights from both lakes, which they use to provide clean drinking water to their own residents, as well as other communities they service.
 

Recreation 

The River and it's Lakes are used for a variety of fun things such as fishing, boating, and hiking through the greenbelt areas that surround it.   

However, none of these are necessarily recommended on the River section starting just south of the Lake Lewisville Dam due to the three landfills in the watershed.  You will know them when you smell them.  As a result, the southern section of the Elm Fork is not nearly as charming and should  probably be avoided.
 

Downstream

The Elm Fork eventually merges with the West Fork to officially become the Trinity River northwest of Downtown Dallas.  Trinity River water then flows southeast through fertile farmland in Central Texas and pine forests of East Texas before reaching the Gulf of Mexico east of Houston near the town of Anahuac.