Evaluation of Groundwater Levels and Movement Near the Rialto-Colton Fault

ER-201035

Objective

The Rialto-Colton Fault in California forms the southwestern boundary of the Rialto-Colton Basin. Questions persist concerning groundwater movement near the fault and the degree to which the fault acts as a barrier to groundwater movement from the Rialto-Colton to the Chino and North Riverside Basins. The Rialto-Colton and Chino Basins have been found to have high perchlorate concentrations. The objective of this project is to gain a better understanding of the direction of groundwater movement within the Rialto-Colton and adjacent basins in the vicinity of the Rialto-Colton Fault based on water-level data. Additionally, this project aims to identify possible locations along the fault where it may not be an effective barrier to groundwater flow and perchlorate transport.

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Technology Description

The Rialto-Colton Fault is a fault zone about 1 mile wide along two-thirds of its northwestern extent. The entire southeastern part of the Rialto-Colton Basin, near the Santa Ana River and Warm Creek, is the fault zone. Data indicates that the fault zone is a series of discontinuous step faults at about the midpoint along its extent. Although the gravity and aeromagnetic data are used to determine faulting in the bedrock, the data also can suggest the location of the fault in overlying sediments. Seismic data collected across the Rialto-Colton Fault indicates that the extent of the fault zone in the overlying alluvium is similar to that of the gravity and aeromagnetic data. Gaps in the fault may act as conduits through which groundwater can flow.

This project’s study area is bounded by Interstates 10, 15, and 215 and includes most of the Rialto-Colton Basin, the eastern Chino Basin, and the western part of the Bunker Hill Basin. The approach involves compilation of available water-level data, evaluation of the available data and identification of data gaps, collection of additional water-level data, and construction of water-level contour maps.

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Benefits

A detailed groundwater contour map in the Rialto-Colton, Chino, and North Riverside Basins in the vicinity of the Rialto-Colton Fault will provide a better understanding of groundwater movement across the fault and shed light on the effectiveness of the fault as a barrier to groundwater flow and the possible transport of perchlorate. (Anticipated Project Completion - 2012)

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Points of Contact

Principal Investigator

Mr. John Izbicki

U.S. Geological Survey

Phone: 619-225-6131

Program Manager

Environmental Restoration

SERDP and ESTCP

Document Types

  • Fact Sheet - Brief project summary with links to related documents and points of contact.
  • Final Report - Comprehensive report for every completed SERDP and ESTCP project that contains all technical results.
  • Cost & Performance Report - Overview of ESTCP demonstration activities, results, and conclusions, standardized to facilitate implementation decisions.
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  • Guidance - Instructional information on technical topics such as protocols and user’s guides.
  • Workshop Report - Summary of workshop discussion and findings.
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