GSI and the Columbia Basin Ground Water Management Area (CBGWMA) created a customizable computer-based water supply planning application to help the Cities of Moses Lake and Othello, Washington understand, assess, and plan potential future municipal water supply activities.


Located in the Columbia Basin, both Cities rely almost exclusively on basalt aquifers for their supply of potable water, industrial water, and the vast majority of their irrigation water. Earlier work by GSI, CBGWMA, and the USGS had highlighted the risk of ongoing and future depletion of the aquifer and ongoing mining of groundwater. Historical and current trends all point to future challenges for cities that are almost wholly reliant on these diminishing basalt aquifer groundwater supplies; like these two Cities.

GSI’s Solution

CBGWMA and GSI used the results of the Columbia Basin Mapping and Aquifer Evaluation Projects to help the Cities conduct an assessment of the specific water supply options available to them. The main outcome of the project was the development of a water supply planning application that presents the Cities’ current and future groundwater supply trends and system demand. It then allows them to input supply options (both groundwater and surface water) in various combinations, resulting in scenarios that can be compared and used for planning for future system changes and source additions. The application allows the Cities’ to compare:

  • Supply and demand projections, including the change in supply
  • Using depletable water supplies versus sustainable water supplies
  • Total water added to the system
  • Total and annualized costs over a pay off period

GSI and CBGWMA customized the water supply planning application for each City. In each case, the team incorporated into the application:

  • Specific water supply sources actually available to each City, and their related costs and capacities.
  • Demand as forecasted in their respective Water Master Plans
  • The sustainability of each water source
  • Inflation rates
  • Pay-off schedule rates

Operations and maintenance costs can also be incorporated. All of these can be modified for any city or water user in question and can be updated when needed. Moreover, the application can continually be used for water supply decision-making into the future.