Surface Infiltration and Unsaturated Zone Characterization in Support of Managed Aquifer Recharge in Bedell Flat, Washoe County, Nevada

Scientific Investigations Report 2021-5137
Water Availability and Use Science Program
Prepared in cooperation with the Truckee Meadows Water Authority
By: , and 


  • Document: Report (10 MB pdf) , XML
  • Data Releases:
    • Data Release - Documentation of VS2DH seepage models—Surface infiltration and unsaturated zone characterization in support of managed aquifer recharge, Washoe County, Nevada
    • Data Release - Supplemental data—Surface infiltration and unsaturated zone characterization in support of managed aquifer recharge, Bedell Flat, Washoe County, Nevada
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Aquifer storage and recovery (ASR) expands the portfolio of public water supply and improves resiliency to drought and future water demand. This study investigated the feasibility of ASR in the Bedell Flat Hydrographic Area using land-based methods including in-channel managed aquifer recharge (MAR) and rapid infiltration basins (RIB). Bedell Flat, one of two flow-through groundwater basins near Reno, Nevada, was a likely candidate for ASR because of its deep basin fill, proximity to supplemental water sources and infrastructure, and lack of development. In-channel MAR feasibility was determined from seepage losses along the Bird Springs ephemeral channel measured using Parshall flumes and heat-as-a-tracer inverse modeling. The feasibility of RIB was evaluated by characterizing vadose zone boreholes installed with roto-sonic drilling to water table. Field characterization of sediment and lithologic descriptions was accomplished at 1-foot (ft) increments. Bulk sediment samples were collected every 5 ft and cores from a split spoon were sampled at 10, 20, 30, 40, 60 and 100 ft below land surface (bls). Collected samples were analyzed for texture, moisture content, and geochemistry.

Infiltration rates in Bird Springs channel increased downgradient with the hydraulic conductivity of the upper reaches ranging from 0.002 to 0.14 meter per hour (m/h) and the lower reaches from 0.5 to 1.5 m/h. Differences in discharge measurements indicate that seepage losses also increase down channel. When normalized to 1 ft of channel stage, modeled seepage loss rates ranged from 0.02 to 5.34 cubic feet per second (ft3/s) per mile (mi). Perched zones of soil moisture residing on top of dry fine-textured, clay-rich layers were prevalent in the Bird Springs drainage, indicating complicated flow paths for any supplement recharge water. Characterization of boreholes in Bird Springs drainage indicates low permeability clay layers 1–10 ft thick interbedded within extensive, grussy sands of high permeability. The presence of low permeability clay layers (1–10 ft thick) prompted a shift in analysis to the adjacent Sand Hills drainage where four additional boreholes indicated fewer perched water zones and at greater depths. Nitrates in the sediment pore-water (a condition that would discourage ASR) were integrated with depth to the aquifer 180 ft bls. Wells BF-MW-04 (Bird Springs) and BF-MW-07 (Sand Hills) contained 4,270 and 2,436 kilograms per hectare of nitrogen, respectively, which could potentially load excessive nitrogen to a receiving aquifer.

An economically viable ASR project requires a minimum input of 2 million gallons per day (approximately 3 ft3/s), which either channel appears to have the sufficient capacity to infiltrate such a volume before reaching the valley bottom of Bedell Flat. However, the trajectory of the infiltrated water is complicated by the lithology and lateral transmissivity of the underlying sediments. There is also concern that this volume of infiltrated water may cause undesirable groundwater levels at the outflow in less than 5 years.

Suggested Citation

Caldwell, T., Naranjo, R., Smith, D., and Kropf, C., 2021, Surface infiltration and unsaturated zone characterization in support of managed aquifer recharge in Bedell Flat, Washoe County, Nevada: U.S. Geological Survey Scientific Investigations Report 2021–5137, 52 p.,

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Acknowledgments 
  • Abstract 
  • Introduction 
  • Purpose and Scope 
  • Bedell Flat Hydrographic Area Description 
  • Methods of Investigation 
  • Results of Seepage Loss Estimates 
  • Results of Unsaturated Zone Characterization 
  • Conceptual Recharge Model for the Bird Springs and Sand Hills Drainages 
  • Conclusions 
  • References Cited 
  • Appendix 1. Measured and Simulated Thermographs for Channel Sediments 
  • Appendix 2. Borehole Characterization Data 
  • Appendix 3. Chip Trays from Roto-Sonic Boreholes
  • Appendix 4. Field Procedure for Roto-Sonic Borehole Field Characterization
  • Appendix 5. Field Textural Lookup Table
Publication type Report
Publication Subtype USGS Numbered Series
Title Surface infiltration and unsaturated zone characterization in support of managed aquifer recharge in Bedell Flat, Washoe County, Nevada
Series title Scientific Investigations Report
Series number 2021-5137
DOI 10.3133/sir20215137
Year Published 2021
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Nevada Water Science Center
Description Report: ix, 52 p.; 2 Data Releases
Country United States
State Nevada
County Washoe County
Other Geospatial Bedell Flat
Online Only (Y/N) Y
Google Analytic Metrics Metrics page
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