Why are construction aggregate quarries located in Temescal Valley?


Temescal Valley is home to one of the richest deposits of high quality portland cement concrete (PCC)-grade aggregate rock in Southern California, according to the California Geological Survey (CGS). It is the backbone of the region's infrastructure.1

Construction aggregates can only be mined in specific areas where mineral resources meet certain quality specifications like those identified by CGS.


The local mining operations ensure the region's infrastructure is maintained and developed to sustain the quality of life for those living and working the region.

However, the permitted level of construction aggregate resources are insufficient to satisfy projected demand. Additional permitted resources, like the proposed Olsen Canyon Project, are needed. Read More →





Public Parks & Recreation Facilities

Public Parks & Recreation Facilities

The shortage of aggregate has been verified by the California Geological Survey and the California Department of Transportation (Caltrans).

"In February 2006, I sent a letter to you [Transportation Partners throughout California] stressing the need for permitting new aggregate resources within California. As you are aware, these materials are one of the critical resources required to meet current and expected infrastructure improvement needs for transportation improvements, flood protection, and public and private facilities."
- Will Kempton, Director of Caltrans, 2008 Letter

"While we are continuing to work with local and State agencies to help gain approval of new aggregate mining sites throughout the state, there is still much to be done to ensure that these essential resources will be available for development in the far reaches of our long-range plans. I would like to encourage you [Transportation Partners throughout California] to explore new strategies to increase aggregate reserves in your region."
- Malcolm Dougherty, Caltrans Acting Director, 2011 Letter

The Temescal Valley Production Area has been identified by the California Geological Survey as an important source of construction aggregates.2 Read More →


What can we do to fill the gap?

We can permit new construction aggregate sites like the proposed Olsen Canyon Project to ensure the region has the materials it needs to support economic activity and employment.


In what ways do construction aggregates benefit our community?

Construction Aggregate Mining Creates Well-Paying Jobs.

The Temescal Valley construction aggregates operations provide jobs that pay significantly more than the average wage, in the region.

The average salary for workers at construction aggregate quarries in Riverside County is nearly $70,000 a year3.

The county's income per capita is only $30,912; and, the average salary per worker is $49,4014.

Construction Aggregate Mining Encourgages Job Growth.

The construction aggregates industry supports job growth. According to the Bureau of Economic Analysis, for every $1 million in direct economic output from the construction aggregates industry, nearly 7 new jobs are created.

Based on the estimated direct economic impact to the region, the Temescal Valley construction aggregates industry generates more than 751 local jobs.

Construction Aggregate Mining Boosts the Economy.

The Temescal Valley construction aggregates industry directly contributes an estimated $200 million in total economic activity, annually*. Read More →

The proposed Olsen Canyon Project, located on an area classified by CGS, is designed to reduce the construction aggregate shortgage, provides economic stimulus, and creates local jobs. Read More →

*Estimate based on average annual market price and economic multipliers for quarries.


1California Geological Survey. "Aggregate Sustainability of California." Map Sheet 52, Updated 2012.

2California Geological Survey. "Update of Mineral Land Classification for Portland Cement Concrete-Grade Aggregate in the Temescal Valley Production Area, Riverside County, California." Special Report 231. 2014.

3Bureau of Labor Statistics. May 2014 Metropolitan and Nonmetropolitan Area Occupational Employment and Wage Estimates. Retrieved from: http://www.labormarketinfo.edd.ca.gov/msa/riverbern.html

4State of California Employment Development Department data for Riverside-San Bernardino-Ontario MSA 2014. Retrieved from: http://www.dot.ca.gov/hq/tpp/offices/eab/socio_economic_files/2013/Revised_Full_Report.pdf