Groundwater and Surface Water Modeling
Surface Water Reservoir Operational Models
A number of reservoir operational studies have been completed LWS using hydrologic flow data sets to assess the most efficient mode of operation to meet a projected water supply demand while, at the same time, evaluating carryover storage and minimizing spills to evaluate average and firm yields. Water management techniques are also frequently applied and include water conservation and water reuse. Reservoir operational models have been conducted on a number of sites, including Rueter-Hess Reservoir, Orlando Reservoir, Cucharas Reservoir, reservoirs to be used to optimize exchange potential, and augmentation ponds.
Rueter-Hess Reservoir, Parker, Colorado:
Rueter-Hess Reservoir was originally sited by Mr. Lytle in 1991. To bring the project to fruition both environment review and permitting was necessary, in addition to Water Court action to adjudicate a new water storage right. Initially, a reservoir operational model had to be developed to demonstrate purpose and need related to obtaining a Section 404 Permit for the reservoir. These operational studies were used to conduct the environmental assessment of impacts to riparian areas and depletions related to endangered species. These model results were key in obtaining the necessary 404 permits for the dam and reservoir. The reservoir operational model was also used to support the volume of storage sought in Water Court. A decree was obtained for 72,000 acre-feet of storage in Rueter-Hess. Subsequently, after the reservoir had been permitted and built, LWS has conducted numerous operational model studies to evaluate the most efficient use of reservoir storage, given the District’s diverse water rights portfolio, including both current Cherry Creek and Newlin Gulch surface water supplies as well as alluvial aquifer water, and Denver Basin bedrock aquifer water. LWS has also conducted operational model studies to evaluate a projected trans-basin diversion from its Logan County Farms in eastern Colorado, some 100 miles east of Rueter-Hess.
Long-Term Water Supply Strategic Plan, Sterling To Parker, Colorado:
LWS has recently assisted in the technical development of the proposed long-term water supply strategic plan (LTWSSP) for the Parker Water and Sanitation District, a municipal water supply entity, teaming with the Lower South Platte Water Conservancy District, a principally agricultural water supply district. LWS developed a point-flow model of the South Platte River, which included all of the diversions from the river and the water rights calls on the river, to assess water supply availability at various points for the LTWSSP. This plan is the first in Colorado to provide collaboration between municipal and agricultural entities to combine a large water supply diversion and storage project that will benefit both farmers and the growing population of Colorado without having to “buy and dry” farmlands. The project includes two new reservoirs, one downstream reservoir as equalization storage to move water upstream when flows are available as well as release water for irrigation purposes, and a new 72,000-acre-foot reservoir to capture excess surface flows when they are available. An existing 34,000-acre-foot reservoir is also planned to be used as a forebay to move water off the river during high flows and then pump water to the new reservoir. A pump and pipeline system will move water back to Parker (Rueter-Hess Reservoir) and will also deliver water to the South Platte River to supplement available irrigation supplies.
Fort Knox Water Supply Reservoir, Central Alaska:
The Fort Knox Gold Project proposed to process approximate 35,000 tons per day of ore material and needed a large water supply for the mill. LWS personnel developed a reservoir operational model to assess the water supply availability on Solo and Last Chance Creeks relative to building a water supply dam and reservoir downstream of the confluence of the two creeks. Complicating factors in the reservoir operational model were the extreme cold conditions in north-central Alaska (north of Fairbanks), which results in several feet of ice on a reservoir over an approximate 9-month period, and the presence of permafrost on the north-facing slopes which were expected to thaw once the reservoir filled. The results of the reservoir operational study indicated a sufficient water supply could be provided for the mill, even with the complicating factors. This dam and reservoir have been built and have been providing the operational water supplies for the mill for many years.
Orlando And Cucharas Reservoirs, Southern Colorado:
Orlando Reservoir is an off-stream reservoir located on the Huerfano River, while the Cucharas Reservoir is an on-stream reservoir on the Cucharas River, a tributary to the Huerfano River. Both reservoirs are currently adjudicated for irrigation use and LWS has constructed reservoir operational model studies to assess the future yields from these reservoirs, both for continued irrigation use and for potentially adjudicating a change of use in Water Court. A future water supply maximization study has been completed to assess the ultimate yield that can be realized from both the direct flow rights and the storage rights, using the LWS reservoir operational models. The results of the reservoir operational model studies have helped guide the client with decisions regarding future use of the reservoirs.
Timnath Landing Augmentation Pond, Northern Colorado:
A residential and commercial development is proposed in Timnath, Colorado and the property is adjacent to the Poudre River and overlies an ancient buried channel of Box Elder Creek. Because of the local geology, a permanent dewatering system had to be designed to allow the residential and commercial development on the property. Water from the Lake Canal is to be used for augmentation of depletions associated with the dewatering operation. A reservoir operational model was built by LWS to evaluate the on-site storage capacity that would be necessary to manage the changed Lake Canal share water to provide a reliable augmentation supply. The results of the reservoir operational model have assisted the client with evaluating its options relative to the source of its overall augmentation supply. This model was instrumental in our client obtaining the necessary augmentation plan in Water Court to allow project construction to begin.
Hydrologic Flow Modeling To Support NEPA Permitting Of An Off-Stream Reservoir :
To demonstrate purpose and need for obtaining a Section 404 permit at Rueter-Hess Reservoir it was necessary to model the expected available surface water flows for storage in a reservoir on a tributary to Cherry Creek. This analysis utilized existing surface water gage data but also required the superposition of legal water supply availability on the physical surface water flow analysis. These data were also used to assess the impacts to riparian vegetation along Cherry Creek as a result of the change in the hydrologic regime due to the diversion and storage of some native flow.