Durango: Study of sediment sources in Lightner Creek underway

A picture named lightnercreekconfluenceanimasriver.jpg

From The Durango Herald (Dale Rodebaugh):

A coalition of public agencies has acquired funding for a three-phase hydrological study to answer questions that have stumped observers for years: Where does the sediment that Lightner Creek periodically dumps into the Animas River come from, and why? Field work on the study, begun this week, could be done by the end of the year and lead to answers to an environmental problem seen as a potential source of harm to renowned fishing waters. “Sediment comes and goes, but no one knows whether it’s natural or human-induced,” Meghan Maloney, river campaign director at the San Juan Citizens Alliance, said recently. “The reason for concern is that Lightner Creek runs into the Animas at the head of a trout fishery that the Colorado Division of Wildlife gives its highest rating – gold medal.”[…]

Three organizations put up funding for a study – Trout Unlimited $1,000, the Colorado Water Conservation Board $5,000 and the Southwestern Water Conservation District $2,600 – to hire Mark Oliver of Basin Hydrology. Oliver started his field work this week. “I started at the mouth where Lightner Creek runs into the Animas and I’m working my way upstream,” Oliver said. “I’m looking at the channel and flood plain for sediment sources that could come from bank erosion or land-use modification. “The Tech Center watershed and Perins Canyon seem likely sources of silt,” Oliver said. “But my study will confirm whether the deposition is coming from there.” At certain points, Oliver will do sieve analysis – measuring the size of sediment particles. Along with a cross-section analysis of the channel – width, depth and slope – he can determine the movement of sediment. “I’ll focus on sediment sources and the mechanics of how sediment gets to the mouth,” Oliver said. “Then I’ll try to determine if the sediment is natural or caused by people – for example, the landfill above the Tech Center.”

More Animas River watershed coverage here and here.

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