From The Mountain Mail (Joe Stone):
Groundwater levels around Yale Lake have dropped approximately 1 foot in the past 2 months since the lake stopped receiving inflows from the Thompson Ditch, but the area continues to retain water within 6 feet of the surface.
Chris Manera, professional engineer, relayed the information during the Upper Arkansas Water Conservancy District board of directors monthly meeting Wednesday in Salida.
Reporting on efforts to dry up land formerly irrigated by the Thompson Ditch, Manera said the water level in Yale Lake is decreasing as the reservoir loses water to seepage and evaporation.
Still, the depth of the water table “is not changing quickly,” Manera said, indicating the geological presence of a “high confining layer” within 20 feet of the surface that creates a saturated zone above the surrounding aquifer.
Manera said a release of water from Harvard Lake “had no effect” on the shallow saturated zone and indicated water would likely be released from Yale Lake in an effort to lower groundwater levels below 6 feet from the surface.
Reducing the water table to at least 6 feet below the surface would put the water out of reach for plants, a key requirement for drying up agricultural land in order to change the use of the water.
Manera presented measurements recorded at nine district piezometers and nearby private wells that show water levels at 6 feet below the surface just west of Yale Lake. To the south and east of Yale Lake, however, water levels remain closer to the surface.
Manera noted a 10-foot east-to-west drop in the subsurface water gradient with groundwater flows moving west to east, directly toward Franklin Spring, which feeds Ice Lake. Manera said the receding groundwater has not affected water levels in nearby Harvard and Ice lakes.
Terry Scanga, Upper Ark district general manager, updated board members on the situation at O’Haver Lake, indicating the district is releasing water from the reservoir for augmentation operations.
Scanga said the reservoir is currently at 84 percent of its 180-acre-foot capacity, and releases will continue through March and possibly into April, leaving approximately 146 acre-feet of water in O’Haver by the end of March.
Scanga said the Upper Ark district policy has been to keep O’Haver Lake full, but like any reservoir, O’Haver loses water to evaporation. Since the district cannot capture water out of priority, it must use exchanges to keep the reservoir full.
Recent policy changes by the Colorado Water Conservation Board have made exchanges up Grays Creek virtually impossible, prompting district officials to use O’Haver water for augmentation.
Scanga said he believes the district can work with the CWCB staff to create a policy to resolve the issue, and he is hopeful that a site visit this spring will help CWCB officials better understand the issues “on the ground.”
In other business, Upper Ark directors:
Learned that the state approved district augmentation totaling 482.1 acre-feet of water, an increase of 196 acre-feet per month due to the inclusion of augmentation for Nestlé Waters North America’s spring water operation near Nathrop. Learned that conservancy district replacements for 2014 totaled 665.41 acre-feet. Learned that proposed legislation to allow senior water-rights holders to donate water to in-stream flows has been changed to apply only to the Western Slope, but if passed, the bill would deprive downstream rights-holders of return flows. Heard a report showing 2,515.7 acre-feet of district water in storage.
Reviewed a summer streamflow forecast projecting 240,000 acre-feet of water flowing past Salida, which is 98 percent of average.
Learned about progress toward installing a new gauge near the Friend Ranch Reservoir outflow with Poncha Springs sharing the cost of installation and maintenance. Discussed efforts by Young Life to upgrade its Trail West septic system with a pipeline connecting to the Buena Vista waste treatment facility, which would require Young Life to purchase additional augmentation water from the conservancy district. Approved stipulations in two Water Court cases, 04CW96 and 11CW86.