Water Rights Injury Assessments
Spear T Ranch:
The Ranch is located in Morrill County, Nebraska and it has two surface water permits for diversions from Pumpkin Creek. However, over the years ground water use has increased upgradient from the Ranch such that surface flows have continued to diminish due to the hydraulic interaction between the local ground water table and the surface flows and Pumpkin Creek. LWS was requested to develop a numerical surface water/ground water model of Pumpkin Creek and the associated alluvial ground water system, using MODFLOW, to assess the magnitude of injury to the Spear T Ranch water rights. This case was pursued in Nebraska District Court (CI03-16).
Sustainable Water Resources:
Ground water resources are sought to be developed in the San Luis Valley from new, deep confined aquifer wells. Because these wells will be relatively junior within the priority system, and to meet the Confined Aquifer Rules in Division 3, it is necessary to assess the potential injury to other vested water rights. LWS has used the Rio Grande Decision Support System (RGDSS) numerical model, developed in MODFLOW, to simulate the projected pumping of the Sustainable Water Resources wells and to assess the potential for injury. Analyses of many potential well field pumping operations in the RGDSS model indicate that a project of up to 35,000 ac-ft/yr could be developed and an augmentation plan adjudicated to prevent injury to vested water rights.
The Gallegos family owns the Consolidated Larson Ditch, as well as Larson Reservoir Nos. 1 and 2 in the Upper Crow Creek Designated Ground Water Basin. Since these surface water rights pre-date the creation of the designated basin, these rights should be protected from the more junior ground water irrigation pumping occurring upstream of the surface diversion of the Consolidated Larson Ditch. LWS conducted both a field investigation, as well as a hydrogeologic assessment of ground water flow patterns and ground water/surface water hydraulic interaction, to assess how the upgradient irrigation wells were affecting flow at the ditch headgate. These investigations were incorporated into an expert report presented in District Court. The investigation results were utilized to demonstrate the injury being caused by the upgradient alluvial aquifer pumping.