Have you ever wondered what happens to gravel pits? Most of them turn into water storage. https://t.co/UNM2bYIWfC pic.twitter.com/yuakUwZe6H
— Coloradoan (@coloradoan) May 18, 2015
From the Fort Collins Coloradan (Kevin Duggan):
The bodies of water once were strip mines where excavators and bulldozers roamed, pulling up rich deposits of gravel, sand and river rock. Noisy crushing machines sorted out the materials, which went toward building roads, bridges and buildings and decorating gardens.
In their wake, the mining operations left behind deep, gaping pits in the Poudre Valley landscape that over time were transformed into water-storage vessels and “natural” areas.
“There is not a natural lake on the Poudre,” said Rob Helmick, a senior planner with Larimer County. “All of those areas have been mined at some point. In many cases, it happened decades ago.”
A review of aerial photos of the river between Laporte and the Larimer/Weld county line near Windsor showed at least 30 permitted gravel-mining sites and about 70 ponds of various shapes and sizes, Helmick said. Many of the pits likely predate state and county regulations on gravel-mining operations.
A state law passed in 1977 put an end to the practice of abandoning spent gravel pits by requiring reclamation of mining sites, said Tony Waldron, mineral program manager with the Colorado Division of Reclamation, Mining and Safety.
“It used to be a rape-and-escape mentality,” he said. “Operators moved on and left the mines behind.”
Today, an operator must post a bond with the state that is returned only after reclamation work, such as grading and planting native plants to re-vegetate a site, is completed and the permit closed.
The reclamation and treatment a pit receives depends upon its next use. The complexities of state law on water ownership also come into play…
The water volumes may be small compared to large reservoirs, but they matter to the districts, he said. The partnership expects to spend about $17 million on the project.
“We don’t have the return-flow obligations that Greeley has, so we are going for storage,” DiTullio said. “Every little bit helps. And it’s a natural use for those pits.”
State water law requires water managers to account for where their water comes from and where it goes, including evaporation. The pits are lined with clay or have “slurry walls” built around them to keep groundwater out of the facilities.
The state’s permitting process and testing requirements have strict standards, including the slope of a pit, Guggisberg said…
A mined-out gravel pit once was considered a liability by property owners, Waldron said. The pits were sold for low prices or given away to municipalities and counties to use as natural areas.
Attitudes started to change in the 1990s when water storage became a statewide issue and major reservoir projects, such as Two Forks Dam proposed west of Denver, became increasingly difficult and expensive to build.
A law passed in 1981 requiring owners of unlined pits that were connected to groundwater flow to account for evaporation and replace the lost water by was another complication.
Former pits became a viable way to store and release water to meet state regulations for augmenting water lost to evaporation, said Mark Sears, natural areas manager with Fort Collins. Being able to return water to the Poudre motivated the city’s Natural Resources Department to partner with Fort Collins Utilities to build Rigden Reservoir off East Horsetooth Road.
Some ponds are stocked for fishing by the Colorado Division of Wildlife and Parks. The river areas are highly popular, Sears said.
“Just from their scenic value, the river natural areas are great,” he said. “And they are wonderful habitat, especially around the edges, for a variety of species.”
More Cache la Poudre watershed coverage here.