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Dennis Jones the hydrologist in charge of reclamation gave us a behind the scenes tour of a closing mine. The Surface Mine Control and Reclamation Act of 1977 (SMCRA) requires the restoration of mined lands. The Seneca Coal Mine was a surface mine: top soil was scraped off the land and stored; the rock overlying the coal was broken up and removed with a dragline; and back loaders were used to remove the coal. The profitable surface coal was depleted in early January of 2006.
The mine owner, Peabody Coal, is now reclaiming the mined area by using the rock overburden to restore the original contours of the land. Top soil that was previously scraped away is replaced and the area is revegetated. Dennis Jones monitors rainfall, stream discharge, and the quality of water leaving the site. Issues of concern are total dissolved solids, salinity and sulfates. Even though the water quality is poor, ranchers in the area are pleased as after mining there is more water during the drier seasons of the year. Prior to mining the water table was very shallow and runoff in the spring was rapid. Now that the overburden rock is broken up, more precipitation infiltrates and increases summer flows. The mine also has sediment ponds installed on the property to allow suspended sediments to settle out.
Our next stop was the 23,000 acre Fraser Experimental Forest. Drs. Chuck Troendel and Kelly Elder (the former and current project leaders for the forest) described the extraordinary research record and unique opportunities that Fraser provides. The forest was established in 1937 to examine the long term effects of timber harvest and other disturbances on forest hydrology. Today, it would be impossible to find an undisturbed tract of forest land of this size. The primary purpose of the forest is research, but compatible uses such as recreation are allowed also.
Early research in understanding the role of interception in forest hydrology was conducted here. The hydrology of the region is snow dominated. Snow accumulates in the winter and generally starts melting in March. Snow intercepted by trees generally has more surface area exposed and tends to sublimate faster than the snow pack on the ground. Trees use much of the soil moisture for transpiration so clearcuts in the Fraser forest can result in increased water yield. Studies are conducted at both a plot and watershed scale, as it is important to understand the processes and effects of increasing area. Ongoing studies include utilizing remote sensed data to estimate snow water equivalent in snow packs and monitoring the impacts of a large scale beetle infestation that is killing most of the older trees in the forest.
The early days of Leadville were filled with excitement and the prospect of easy riches from the mineral wealth found in the surrounding mountains. Miners would look for signs of yellow boy, an oxidized iron that often indicates the presence of gold. Today the area around Leadville is full of old abandoned mines and their tailing piles. The region also has active and recently active mines. Miners follow the mineral vein into the mountains, the tailings are hauled out of the tunnels and left in large piles. Pyrite in the tailings react with water and oxygen to generate both the tell tale sign of yellow boy and acid mine drainage. Acidic water can hold large concentrations of dissolved metals and is detrimental to aquatic life. The effluent is treated to increase Ph and precipitate out metals at water treatment plants or it is diverted to wetlands, limestone channels, and diversion wells for passive treatment. In addition, tailings piles may be isolated from streams to mitigate the effects of acid mine drainage.
The day started with Fred Patton the project leader of the Upper South Platte Restoration Project describing the challenges of restoring the watershed after the Buffalo Creek fire in 1996 and the Hayman fire of 2002. A large part of his work involves restoring unburned forests to a pre-fire suppression state through mechanical forest thinning and prescribed burns. It is thought that the recent occurences of high-severity fires are in part due to unnaturally high forest densities. The high forest densities result from fire suppression activities.
We moved on to study plots on the Hayman fire to learn about the effects of fire on run-off and erosion. Fire removes vegetation and debris which protect soil from the erosive effects of rain splash and overland flow. A high severity wild fire may also cause soil water repellency. Fires increase the amount of run-off available to detach and transport soil particles. The increased sediment loads damage stream ecosystems, degrade water quality, and reduce water storage capacity of reservoirs. We also visited sites used to investigate the effects of forest roads on erosion. Soils on the road surface are compacted by traffic which decreases the infiltration rate and results in increased run-off. The final stop of the day was an OHV trail where some of the first erosion yields due to OHV traffic are being collected.
The headwaters of Fountain Creek are predominately forested and are located high in the Rocky Mountains, but the creek quickly descends into the growing Colorado Springs metropolitan area. Pikes Peak (14,110 ft) is the highest point in the watershed and Pueblo at 4,640 feet is the lowest. The population of El Paso County has increased by roughly 75% since 1975, the developed and impervious areas of the watershed have increased with the population resulting in dramatic increases in runoff, faster hydrological responses, and hence greater flood hazards. The growing population's need for water also has an interesting effect on the watershed as 80% of Colorado Spring's water comes from the western side of the mountains. In pre-European times Fountain Creek would dry out late in the summer. But with 12 wastewater plants contributing discharge, the creek flows year round. The increased low flows in the watershed cause severe bank erosion as more flow increases sediment transport. The bonus side trip of the day was stopping to survey flood damage on Highway 67 resulting from increased flows from the Hayman burn area.
Bent's Old Fort is a reconstruction of an adobe trading post from the 1840's; it was built on the original Fort's foundations to celebrate our nation's bicentennial in 1976. The Fort Lyons irrigation canal is North of the Fort and the Arkansas River meanders around the Fort to the South and West. In 1999 the historic foundations were damaged by flooding, the National Park service asked CSU to investigate the cause. A series of ground water level wells were installed and compared with stream gages. During the study ground water moved from the direction of the irrigation canal towards the river, ground water also moved across the meander. Because of drought conditions the exact cause of the flooding was not ascertained, but the Fort appears to be at a tipping point and could be flooded from either the Arkansas which is experiencing bed aggregation due to an upstream reservoir or from the irrigation canal. After touring the historic fort, we visited La Junta's reverse osmosis water treatment plant. Despite high operating expenses, the plant removes tons of dissolved salts from the drinking water.
