From The Colorado Sun (Michael Booth):
Toss a Frisbee too far at the disc golf course in west Denver and you’ll hit water burbling at the bottom of Lakewood Gulch.
Your errant Frisbee shouldn’t be underwater. Not this time of year. The other stream that runs into the confluence that makes up the disc golf park has a more historically accurate name: Dry Gulch.
A new study from Colorado State University researchers shows that about 80% of the water running through Denver’s inviting stream parks late in the summer flows there from lawns drenched in Denver tap water and leaks from the agency’s intricate system, not from snow runoff or foothills rain.
By history, geology and hydrology, these greenbelts should be bone dry. It’s only the return flow from all your lawn watering that makes a Denver stream anything other than a dry gulch for much of the year, according to the study. Watering to excess — meaning the grass doesn’t need all of it or the sprinklers are hitting concrete instead of green space — makes up most of that 80%. Leaking pipes and system flushes flowing down into stream beds make up the rest.
“It was surprisingly high,” said lead researcher Aditi Bhaskar, assistant professor at CSU’s Department of Civil and Environmental Engineering. Water engineers know tap water flows have an influence on urban streams, but Bhaskar had not expected them to make up effectively the entire creek.