Humboldt River Basin Assessment

December 1998

Phase One Progress

Phase Two Plans

Introduction

In October 1995 the U.S. Geological Survey (USGS), in cooperation with the Nevada Department of Conservation and Natural Resources and the U.S. Bureau of Land Management, began an assessment of the regional water resources of the Humboldt River Basin. This assessment was undertaken in response to concerns over increasing demand for the limited water resources of the basin and potential effects of mine dewatering during the past 10 years. The assessment has focused on 14 hydrographic areas in the middle Humboldt River Basin (fig. 1). This part of the basin includes large areas of irrigated agriculture as well as most of the large gold mining operations in northern Nevada. The Humboldt River Basin Assessment was planned as a series of phased studies. This report discusses activities completed during phase one of the assessment (Oct. 1995-Sept. 1998), and activities that are planned for phase two (Oct. 1998-Sept. 2003). Four mining companies provided assistance for phase one of the assessment--Barrick Goldstrike Mines Inc., Getchell Gold Corporation, Newmont Gold Company, and Santa Fe Pacific Gold Corporation. As of December 1998, Barrick Goldstrike Mines Inc., had provided assistance for phase two. Newmont Gold Company had also indicated its intention to provide assistance.

Figure 1. Locations of Humboldt River Basin and middle part of basin (shaded), north-central Nevada.

Phase-One Activities
October 1995-September 1998

Hydrologic Data--The objective of this part of the study was to make USGS hydrologic data available on the internet. The Humboldt Hydrology website, <http://nevada.usgs.gov/humb/>, provides links to USGS data bases that store streamflow data, water-level data for wells, and water-quality data for surface water and ground water. This website also contains the long-term plan for Humboldt River Basin Assessment studies, phase-one progress reports for fiscal years 1996 and 1997, and a bibliography of reports pertinent to the middle Humboldt River Basin.

Hydrogeologic Framework and Ground- Water Levels in the Middle Humboldt River Basin--These two activities were combined into a single study, the results of which will be published by USGS in early 1999. The first part of the report provides descriptions of the different rocks and deposits that either form aquifers or impede the movement of ground water. The second part of the report discusses ground-water levels for 1982 and 1996 and water-level changes during different periods of record.

Water Budgets in the Middle Humboldt River Basin--This activity has consisted of developing a systematic approach for refining water budgets. The method is based on analyses of current precipitation and streamflow data and on using satellite imagery to regionalize evapotranspiration measurements. So far, the method has been used to refine water budgets for Pine, Carico Lake, and Upper Reese River Valleys (fig. 1). The study results will be presented in a report that will be published by USGS in 1999.

Ground-Water Use in the Middle Humboldt River Basin--This activity includes two parts. The first part is to inventory (1) locations of production wells used for irrigation, mining, and municipal purposes, and for generation of electricity and (2) lands that are irrigated with ground water. The second part is to measure discharge and power-consumption rates of irrigation wells, to develop relations for estimating ground-water withdrawals for irrigation in individual basins. This study began in the last year of phase one (1998) and will be completed in the first year of phase two (1999).

Phase-Two Activities
October 1998-September 2003

Ground-Water Use--Please refer to the previous section.

Water Budgets in the Middle Humboldt River Basin--A systematic approach for estimating basin water budgets was developed and applied to Pine, Carico Lake, and Upper Reese River Valleys during phase one of the assessment. In phase two the approach will be used to develop water budgets for the remaining 11 hydrographic areas in the middle Humboldt River Basin.

Computer Model of Ground-Water and Surface-Water Flow in the Middle Humboldt River Basin--The objective of this activity is to develop a computer model that will simulate the transient effects of different water uses and climate variability on ground-water levels and streamflow in the middle Humboldt River Basin. The modeling process will begin with construction of a steady-state ground-water flow model and a separate streamflow routing model. The two initial models and the final transient model will be based on

• Results of the hydrogeologic-framework, water-level, water-use, and water-budget studies completed in phases one and two,
• Aquifer properties compiled for rocks and deposits in the study area,
• Quantitative analysis of Humboldt River streamflow records,
• Measurement of Humboldt River channel cross sections, and
• Measurement of the interaction of surface water and ground water along the river channel.

The results of these phase-two studies will be published by USGS as they are completed.