Sand Mining in California's Central Coast Region

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An environmental summary created by the ENVS 560/L Watershed Systems class at CSUMB.

This page gives a short history of sand mining in California's Central Coast Region and highlights the CEMEX Lapis Plant. The page does not discuss gravel mining that occurs inland.


Southern Monterey Bay Region in the central coast of California was the most intensively mined shoreline in the United States from 1906-1990. [1] The majority of sand mines were closed in 1990 due to assumptions that mining increased coastal erosion. The CEMEX Lapis Plant, located in the town of Marina, Monterey County, is the only sand mine in all of California that continues to operate. Best estimates suggest that the CEMEX plant mines nearly 300,000 tons of sand annually. [2] In 2016, the California Coastal Commission notified CEMEX of its intent to commence a cease and desist order for violations of the California Coastal Act. On 13 July 2017, The California Coastal Commission and CEMEX settled that Cemex will shut down operations by 31 December 2020 and avoid litigation. [3]. The agreement will end a more than century long era of sand mining in the Monterey Bay.


The only sand mining plant currently operating in California's Central Coast region, and the United States, is located in the City of Marina, Monterey County, California. The CEMEX Lapis Plant is located eight miles north of Monterey, California along Highway 1 and within the Lower Salinas River Watershed. [4]

Resources At Stake

Excavation of approximately 300,000 tons of sand each year can impact the following resources along the Monterey Bay shoreline:

  • Sand
    • A valuable resource that is used to make glass, computer chips, in cement to build houses and roads, and more. [5]
    • Provides protection from extreme conditions (i.e. flood, large storms, sea level rise)
  • Water supply
    • Sand mining can extend so deeply that it affects ground water, springs, underground wells through lowering of the water table. [6]
  • Species Biodiversity
  • Sub-tidal Habitat (Rocky Reef, Kelp forests, eelgrass beds)
  • Coastal/Sandy Beach habitat
  • Dune Habitat
  • Infrastructure
    • Existing Coastal Development (hotels, condos, etc.)
    • Highways & Bridges
  • Special Status Species Habitat - western snowy plover, Smith's blue butterfly & black lesless lizard
    • In December 2014, CalAm began work on a test slant intake well located at the CEMEX sand mining facility in North Marina[7]. Due to the presence of threatened Western Snowy Plover breeding grounds near the test slant well, the location had to be returned to its original conditions by February 28, 2015[8].


Various private and public organizations have interests in sand mining. Some of these are:

Local Government


  • CEMEX - Mexico-based, global building materials company which owns the CEMEX Lapis Plant in Marina, CA. [9]



Laws, policies, & regulations

CEMEX claims that because its operation precedes the California Coastal Act of 1976, it had vested rights to continue mining sand without acquiring further permits. [2] However, the Coastal Commission found that the illegal dredge pond on site and an increase in extraction activity overstep the bounds of the vested rights. [2]

The agreement for the closure of the plant has several conditions for the future of the property, including a restricted deed so that the land must be purchased primarily for conservation purposes and will include public access. [3]

The City of Marina put out a request for proposals for a Local Coastal Plan update, in which one task includes drafting a vision for the reuse of CEMEX sand mine. [10]

Systems and Processes

CEMEX mines an estimated 200,000 cubic yards of sand per year. [2] Excavation of sand in the lower watershed increases the grade and creates a new base level for which the entire watershed must equilibrate. The general argument is that mining diminishes sand deposits on beaches and accelerates erosion. Sand mining in coastal dune systems can lead to long term erosion of approximately 0.5 to 1.5 meters per year.[11] Sand is a valuable part of the coastal land and dune ecosystem and is not a renewable resource.[12] The Monterey Bay tidal system moves sand along the shore, therefore sand removed from one location impacts the entire shoreline.[13]

The southern Monterey shoreline on average is the most erosive shoreline in California [14].

Erosion Rates in Southern Monterey Bay[15]:

Monterey: 1 ft / year

Seaside: 3 ft/year

Marina: 6 ft/ year


Coastal Retreat in California's Central Coast Region, specifically Southern Monterey Bay, has the fastest rate of erosion in California.[14] Since the retreat is occuring in the Monterey Bay National Marine Sanctuary, scientists are determined to find possible mitigation efforts, reasons for high rates, and, specific hot spots.

Recent research includes:

  • Thorton et al. (2006) looked at sand mining impacts on long-term dune erosion in southern Monterey Bay [1]
  • Storlazzi and Field (2000) studied sediment distribution and transport along the Monterey Peninsula and Carmel Bay [16]
  • Coastal Regional Sediment Management Plan For Southern Monterey Bay prepared by Williams et al. (2008). [17]
  • Hapke et al. (2006) wrote the National Assessment of Shoreline Change Part 3: Historical Shoreline Change and Associated Coastal Land Loss Along Sandy Shorelines of the California Coast [14]


There are a variety of tools that can be used to assess the effects of sand mining and/or coastal retreat.

  • ArcGIS and the Digital Shoreline Analysis System (DSAS) toolbox can be used to monitor changes in beach width.
  • Stereo Photogrammetry [1]
  • LIDAR Measurements [1]
  • GPS Surveys [1]
  • Historical aerial photography

Future research

The Coastal Regional Sediment Management Plan for Southern Monterey Bay lists potential ways to address the issue of coastal erosion.

Continued study of beach erosion rates in the Southern Monterey Bay after the shutdown of the CEMEX plant will help confirm the impacts of sand mining. CSUMB is planning to continue erosion studies at the site.

CEMEX In The News

Santa Cruz Sentinel Mar 16, 2016

Monterey County Weekly Jan 14, 2016 Sept 1, 2014 2014

Monterey Herald Aug 26, 2013

Monterey Herald Aug 26, 2013

Sierra Club Jan 2012


  1. 1.0 1.1 1.2 1.3 1.4 Thornton et al. 2006. Sand Mining Impacts on Long-term Dune Erosion in Southern Monterey Bay. Marine Geology 229.1:45-58.
  2. 2.0 2.1 2.2 2.3 California Coastal Commission. 2017. CCC-17-CD-02 (CEMEX).
  3. 3.0 3.1 [ California Coastal Comission. 2017. CONSENT SETTLEMENT AGREEMENT AND CEASE AND DESIST ORDER CCC-17-CD-02. State of California Natural Resources Agency.]
  4. CEMEX Lapis Plant
  5. Sand Wars Movie Website
  6. Environmental Impacts
  7. In brief: Test slant well intake for Monterey Peninsula project now underway
  8. MPWSP Temporary Slant Test Well, Project Description
  9. CEMEX Website About Us Page
  10. [ City of Marina.2017. Request for Proposals. Local Coastal Plan Update Preparation of Sea Level Rise Vulnerability Assessment, Risk Assessment, and Adaptation Planning.]
  11. [1]
  12. [2]
  13. Sierra Club - Beach Erosion caused by CEMEX sand mining in Marina
  14. 14.0 14.1 14.2 Hapke CJ et al. 2006. USGS. National Assessment of Shoreline Change Part 3: Historical Shoreline Change and Associated Coastal Land Loss Along Sandy Shorelines of the California Coast
  15. California Coastal Erosion Response to Sea Level Rise
  16. Storlazzi, CD and Field, ME. 2000. Sediment distribution and transport along a rocky, embayed coast: Monterey Peninsula and Carmel Bay, California. Marine Geology 170.3: 289-316.]
  17. Coastal Regional Sediment Management Plan For Southern Monterey Bay



This page may contain student work completed as part of assigned coursework. It may not be accurate. It does not necessary reflect the opinion or policy of CSUMB, its staff, or students.