The Comal River may be the shortest river in the world, check it out in the Guinness Book of World Records. Just under 3 miles in length, the river begins and ends near downtown New Braunfels. The source of the Comal River begins from Comal Springs, which consists of many small springs located in and around Landa Park and Landa Lake. The springs form the Comal River, which eventually joins the Guadalupe River in the heart of downtown New Braunfels. The Comal River is popular for tubing and swimming. The Comal River features one of the largest collections of springs in Texas with an approximate 8 million gallons of water consistently flowing out of the springs every hour. The water is pure and sparkling clear and maintains a
relatively constant temperature of about 72 degrees all year. Many local residents swim in the Comal River year round.
http://www.texastubes.com/river_conditions.htm