Each year, Denver street sweepers collect enough crud to fill Coors Field 9 feet deep

Street sweeping is about far more than petty fines. Denver's water and air quality depend on it.

LOOK: What the Butterfly Pavilion’s fluttery new exhibit teaches us about Colorado ecosystems

“They’re beautiful yes, but they’re also important," said Sarah Garrett, the Pavilion's in-house butterfly and moth biologist.

Challengers claim victories in Denver teachers union elections, race for president heading for recount

A slate of progressive, social justice-oriented candidates won a majority of seats up for grabs in the Denver teachers union election.

Study: Global warming is already shrinking the overtaxed Colorado River

House votes to eliminate gas flaring rule that sought to reduce methane emissions

Energy companies frequently "flare" or burn off vast supplies of natural gas at drilling sites because it earns less money than oil.

The Colorado snowpack is bulging, plus here’s a toilet that doubles as a sink

155 percent: That's how we're quantifying how much more than average the Colorado snow pack is bulging as of last week.

These students are going to figure out the per-cow cost of the National Western — in water, electricity and poop

Denver has no idea how much energy and water the National Western Center uses or how much waste it produces.

Feds want mining companies to pay more for coal from public lands — but Trump may not follow through

Younger, vocal group of Denver teachers pushing union to be more aggressive, activist

A group of Denver teachers, many of them young and social justice-minded, has formed a caucus within the city’s teachers union with the goal of pushing the union to be more progressive — and more aggressive.

LOOK: An archive of pressed flowers (and weeds) at the Denver Botanic Gardens reflects changing temperatures

Underneath the Denver Botanic Gardens' greenhouse, you'll find the herbarium, a massive library of pressed plants collected over the course of a century.

Conservatives wonder if a Trump presidency offers a chance to change control of federal lands

Sage grouse habitat would be protected under new wildfire and restoration plan

The plan is a how-to guide that follows Interior Secretary Sally Jewell's order calling for a "science-based" approach to safeguard the greater sage grouse.

Residents near Colorado Springs sue six companies after drinking contaminated well water

Colorado residents sue 3M and other manufacturers for water contamination.

NASA finds natural gas production is causing methane hot spots over the Four Corners region

Study: Most sources of methane hot spot are gas facilities

See the start of the Gold King Mine spill: “What do we do now?”

Navajo Nation endorses Superfund cleanup of Colorado mines

The Navajo Nation has formally endorsed a Superfund cleanup of mines, including one that released millions of gallons of wastewater into Navajo land.

Work crews returning to site of massive Colorado mine spill

Crews are returning to the scene of a massive mine waste spill in southwestern Colorado to stabilize the mine opening with steel bracing and concrete.