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   Party At-A-Glance Report

  
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General Information
Party ID Party Name Party Classification Mailing Address Work Phone Email/Website
487446 MP Mine Operations LLC Privately-Owned Business 67750 Bailey Road Mountain Pass, CA 92366 702-540-2787 sbaker@mpmaterials.com
  
  
  
  
Expand/Contract Related Places
Related Places
Place ID Place Name County Region Place Type Relationship to Party Relationship Start Date Relationship End Date
890508 North Overburden Stockpile Development MPMO San Bernardino 6B Dredge/Fill Site Owner 09/25/2023 None
757215 Mountain Pass Mine-Revised Mine & Reclamation Plan San Bernardino 6B Dredge/Fill Site Owner 09/28/2010 None
246044 Onsite Evaporation Ponds San Bernardino 6B Surface Impoundment Owner 07/12/2017 None
244589 North Tailing Pond P-16 San Bernardino 6B Metal Mining Owner 07/12/2017 None
241611 Mountain Pass P-1 Closure San Bernardino 6B Metal Mining Owner 07/12/2017 None
241610 Mountain Pass Mine & Mill Ops San Bernardino 6B Metal Mining Owner 07/12/2017 None
220454 DOMESTIC WASTEWATER T&DFs San Bernardino 6B Wastewater Treatment Facility Owner 07/12/2017 None
215314 COMMUNITY & CO LANDFILLS-Molycorp San Bernardino 6B Land fill Owner 07/12/2017 None
Total Related Places: 8
  
  
  
  
Expand/Contract Related Parties
Related Parties
Party ID Party Name Party Type Role/Relationship Relationship Start Date Relationship End Date Classification
629234 Aaron Case Person Employee 08/01/2019 None None
622685 Steven Baker Person Legally Responsible Official 03/11/2021 None None
605017 John Espinoza Person Employee 07/12/2017 None None
547600 Jeffrey Hogan Person Legally Responsible Official 07/16/2014 07/11/2017 None
508765 Mark Smith Person Owner Contact 06/01/2009 07/11/2017 None
Total Related Parties: 5
  
  
  
  
Expand/Contract Regulatory Measures
Regulatory Measures (non-enforcement)
Reg. Measure ID Regulatory Measure Type Region WDID Status Program Order No. RM Effective Date RM Termination Date Relationship Relationship Start Date Relationship End Date Amended?
454473 Enrollee - WDR 6V 6B362309006 Active CERFILLEXC R6T-2003-0004 03/18/2024 None Discharger 09/25/2023 None N
388260 WDR 6V 6B360011004 Active WDRMUNIENROTH WQ 2014-0153-DWQ 11/07/2012 None Discharger 06/01/2009 None N
377626 WDR 6V 6B362098001 Active LNDISPOTH R6V-2010-0047 10/14/2010 None Discharger 07/10/2017 None N
376674 Enrollee - 401 Certification 6V 6B361009001 Historical CERFILLEXC R6T-2003-0004 12/02/2010 12/02/2020 Discharger 09/28/2010 None N
306717 WDR 6V 6B369706002 Active LFNONOPER R6V-2006-0024 06/14/2006 None Discharger 07/10/2017 None N
148025 WDR 6V 6B360011004 Historical WDRMUNIOWTS 01-018 04/11/2001 06/19/2013 Discharger 06/01/2009 None N
148001 WDR 6V 6B360008001 Active LNDISPOTH 00-074 09/14/2000 None Discharger 07/10/2017 None N
145895 WDR 6V 6B362098001 Historical LNDISP 91-836 06/13/1991 10/14/2010 Discharger 06/01/2009 None N
133369 WDR 6V 6B369807003 Active LNDISPOTH R6V-2005-0011 04/14/2005 None Discharger 07/10/2017 None N
132920 WDR 6V 6B360009001 Active LNDISPOTH R6V-2004-0042 10/14/2004 None Discharger 07/10/2017 None N
Total Regulatory Measures: 10
  
  
  
  
Expand/Contract Violations
Violations within the past five years
Violation ID Occurrence Date Violation Type Violation Description(-) Violation Status Priority Source Facility Name Violated Reg. Meas. ID Violated Reg. Meas. Order No. Linked to Enf.
1144261 03/17/2025 Unauthorized Discharge 325 gallons of sodium hydroxide spilled. Release was stopped for line repair. On site personnel and equipment including vacuum truck cleaned up solution, impacted soil removed. A line carrying 32% sodium hydroxide ruptured and impacted the ground. The line was turned off, while repairs were being made. The spill was contained and vacuumed up onsite, impacted soil was remediated. ECM Doc handle # 11563968 Violation N Report Mountain Pass Mine & Mill Ops 377626 R6V-2010-0047 N
1144258 09/06/2024 Unauthorized Discharge Cal-OES 24-5040 Line failure caused 32% sodium hydroxide spill onto ground. MPMO staff called Lahontan on Friday for clean up input. Material being pumped into sump and neutralized with weak acid until neutral pH achieved.Reporting party stated that there was a line failure from a line that leads to a tank causing the release onto the ground. The release has been stopped and contained. No storms drains or waterways impacted Violation N Report Mountain Pass Mine & Mill Ops 377626 R6V-2010-0047 N
1105293 05/26/2022 Unauthorized Discharge Recovery well water is collected and stored in a tank near P-16. The tank has an effluent line that runs to the 204 and then out to the evaporation ponds. A valve in the effluent line was inadvertently closed causing a release of 50-100 gallons of recovery water. Violation N Complaint Onsite Evaporation Ponds 133369 R6V-2005-0011 Y
Report currently showing last five years of violations. Click here to return to viewing one year of violations. Refer to the Interactive Violation Report for more data.
Total Violations: 3
*Click the "(+/-) Violation Description" link to expand and contract the violation description.
  
  
  
  
Expand/Contract Enforcement Actions
Enforcement Actions
Enforcement ID Enforcement Type Enf. Order No. Title Program Effective Date Status
449817 Oral Communication None Oral Com 05/27/2022 for MP Mine Operations LLC LNDISPOTH 05/27/2022 Historical
429031 13267 Letter None 13260 Letter for GILTON RESOURCE RECOVERY TRANSFER FACILITY WDRINDIVSML 02/20/2019 Historical
428308 Oral Communication None Oral Com 01/03/2019 for MP Mine Operations LLC LNDISPOTH 01/03/2019 Historical
428307 Oral Communication None Oral Com 01/02/2019 for MP Mine Operations LLC LNDISPOTH 01/02/2019 Historical
428304 Oral Communication None Oral Com 01/02/2019 for MP Mine Operations LLC LNDISPOTH 01/02/2019 Historical
425637 Oral Communication None Oral Com 10/11/2018 for MP Mine Operations LLC LNDISPOTH 10/11/2018 Historical
423561 Oral Communication None Oral Com 07/23/2018 for MP Mine Operations LLC LNDISPOTH 07/23/2018 Historical
423519 Oral Communication None Oral Com 08/14/2018 for MP Mine Operations LLC LNDISPOTH 08/14/2018 Historical
423516 Oral Communication None Oral Com 08/14/2018 for MP Mine Operations LLC LNDISPOTH 08/14/2018 Historical
423514 Oral Communication None Oral Com 08/14/2018 for MP Mine Operations LLC LNDISPOTH 08/14/2018 Historical
423513 Oral Communication None Oral Com 08/14/2018 for MP Mine Operations LLC LNDISPOTH 08/14/2018 Historical
423505 Oral Communication None Oral Com 08/14/2018 for MP Mine Operations LLC LNDISPOTH 08/14/2018 Historical
423504 Oral Communication None Oral Com 08/14/2018 for MP Mine Operations LLC LFNONOPER 08/14/2018 Historical
419741 Oral Communication None Oral Com 02/21/2018 for MP Mine Operations LLC LNDISPOTH 02/21/2018 Historical
402399 Oral Communication None Oral Com 07/29/2015 for Molycorp Minerals LLC LNDISPOTH 07/29/2015 Historical
402179 Oral Communication None Oral Com 07/21/2015 for Molycorp Minerals LLC LNDISPOTH 07/21/2015 Historical
401788 Oral Communication None Oral Com 06/29/2015 for Molycorp Minerals LLC LNDISPOTH 06/29/2015 Historical
400262 Oral Communication None Oral Com 03/02/2015 for Molycorp Minerals LLC LNDISPOTH 03/02/2015 Historical
399866 Oral Communication None Oral Com 01/28/2015 for Molycorp Minerals LLC LNDISPOTH 01/28/2015 Historical
399730 Oral Communication None Oral Com 01/20/2015 for Molycorp Minerals LLC LNDISPOTH 01/20/2015 Historical
399720 Oral Communication None Oral Com 01/15/2015 for Molycorp Minerals LLC LNDISPOTH 01/15/2015 Historical
399719 Oral Communication None Oral Com 01/12/2015 for Molycorp Minerals LLC LNDISPOTH 01/12/2015 Historical
399518 Oral Communication None Oral Com 12/18/2014 for Molycorp Minerals LLC LNDISPOTH 12/18/2014 Historical
399517 Oral Communication None Oral Com 12/19/2014 for Molycorp Minerals LLC LNDISPOTH 12/19/2014 Historical
399516 Oral Communication None Oral Com 10/29/2014 for Molycorp Minerals LLC LNDISPOTH 10/29/2014 Historical
399515 Oral Communication None Oral Com 12/15/2014 for Molycorp Minerals LLC LNDISPOTH 12/15/2014 Historical
398937 Notice of Violation None NOV 11/20/2014 for Molycorp Minerals LLC LNDISPOTH 11/20/2014 Active
397929 Oral Communication None Oral Com 08/07/2014 for Molycorp Minerals LLC LNDISPOTH 08/07/2014 Historical
397928 Oral Communication None Oral Com 07/23/2014 for Molycorp Minerals LLC LNDISPOTH 07/23/2014 Historical
397425 Clean-up and Abatement Order R6V-2014-0062 CAO R6V-2014-0062 for Molycorp Minerals LLC LNDISPOTH 07/22/2014 Active
397332 Oral Communication None Oral Com 07/09/2014 for Molycorp Minerals LLC LNDISPOTH 07/09/2014 Historical
397331 Oral Communication None Oral Com 07/03/2014 for Molycorp Minerals LLC LNDISPOTH 07/03/2014 Historical
397308 Oral Communication None Oral Com 06/09/2014 for Molycorp Minerals LLC LNDISPOTH 06/09/2014 Historical
397167 Oral Communication None Oral Com 06/24/2014 for Molycorp Minerals LLC LNDISPOTH 06/24/2014 Historical
397002 Oral Communication None Oral Com 06/09/2014 for Molycorp Minerals LLC LNDISPOTH 06/09/2014 Historical
396974 Oral Communication None Oral Com 09/23/2013 for Molycorp Minerals LLC LNDISPOTH 09/23/2013 Historical
396973 Oral Communication None Oral Com 09/20/2013 for Molycorp Minerals LLC LNDISPOTH 09/20/2013 Historical
396143 Oral Communication None Oral Com 05/05/2014 for Molycorp Minerals LLC LNDISPOTH 05/05/2014 Historical
396142 Oral Communication None Oral Com 04/23/2014 for Molycorp Minerals LLC LNDISPOTH 04/23/2014 Historical
395610 Oral Communication None Oral Com 04/04/2014 for Molycorp Minerals LLC LNDISPOTH 04/04/2014 Historical
395386 Oral Communication None Oral Com 02/28/2014 for Molycorp Minerals LLC LNDISP 02/28/2014 Historical
394958 Oral Communication None Oral Com 11/14/2013 for Molycorp Minerals LLC WDRMUNIENROTH 11/14/2013 Historical
394956 Oral Communication None Oral Com 01/21/2014 for Molycorp Minerals LLC WDRMUNIENROTH 01/21/2014 Historical
394954 Oral Communication None Oral Com 01/21/2014 for Molycorp Minerals LLC WDRMUNIENROTH 01/21/2014 Historical
394953 Oral Communication None Oral Com 01/09/2014 for Molycorp Minerals LLC WDRMUNIENROTH 01/09/2014 Historical
394880 Oral Communication None Oral Com 01/15/2014 for Molycorp Minerals LLC LNDISP 01/15/2014 Historical
394469 Oral Communication None Oral Com 01/03/2014 for Molycorp Minerals LLC LNDISPOTH 01/03/2014 Historical
394464 Oral Communication None Oral Com 10/08/2013 for Molycorp Minerals LLC LNDISP 10/08/2013 Historical
394463 Oral Communication None Oral Com 07/31/2013 for Molycorp Minerals LLC LNDISP 07/31/2013 Historical
394461 Oral Communication None Oral Com 12/16/2013 for Molycorp Minerals LLC LNDISP 12/16/2013 Historical
394385 Notice of Violation None NOV 12/24/2013 for Molycorp Minerals LLC LNDISP 12/24/2013 Historical
394379 Notice of Violation None NOV 12/20/2013 for Molycorp Minerals LLC LNDISP 12/20/2013 Active
394347 Oral Communication None Oral Com 12/16/2013 for Molycorp Minerals LLC LNDISP 12/16/2013 Historical
394136 Oral Communication None Oral Com 12/05/2013 for Molycorp Minerals LLC LNDISP 12/05/2013 Historical
393507 Notice of Violation None NOV 10/10/2013 for Molycorp Minerals LLC LNDISPOTH 10/10/2013 Active
392999 Staff Enforcement Letter None SEL 08/08/2013 for Molycorp Minerals LLC LNDISP 08/08/2013 Historical
391807 Oral Communication None Oral Com 06/17/2013 for Molycorp Minerals LLC LNDISP 06/17/2013 Historical
390181 Oral Communication None Oral Com 04/11/2013 for Molycorp Minerals LLC LNDISP 04/11/2013 Historical
390179 Oral Communication None Oral Com 03/08/2013 for Molycorp Minerals LLC LNDISP 03/08/2013 Historical
390178 Oral Communication None Oral Com 02/28/2013 for Molycorp Minerals LLC LNDISP 02/28/2013 Historical
390177 Oral Communication None Oral Com 01/16/2013 for Molycorp Minerals LLC LNDISP 01/16/2013 Historical
390176 Oral Communication None Oral Com 01/16/2013 for Molycorp Minerals LLC LNDISP 01/16/2013 Historical
389535 Oral Communication None Oral Com 06/01/2012 for Molycorp Minerals LLC LNDISP 06/01/2012 Historical
389534 Oral Communication None Oral Com 09/24/2012 for Molycorp Minerals LLC LNDISP 09/24/2012 Historical
389533 Oral Communication None Oral Com 09/14/2012 for Molycorp Minerals LLC LNDISP 09/14/2012 Historical
389493 Oral Communication None Oral Com 03/05/2013 for Molycorp Minerals LLC LNDISP 03/05/2013 Historical
389048 Oral Communication None Oral Com 06/01/2012 for Molycorp Minerals LLC LNDISP 06/01/2012 Historical
388942 Notice of Violation None NOV 01/29/2013 for Molycorp Minerals LLC LNDISP 01/29/2013 Historical
388275 Notice of Violation None NOV 11/20/2012 for Molycorp Minerals LLC LNDISPOTH 11/20/2012 Active
388247 Oral Communication None Oral Com 11/27/2012 for Molycorp Minerals LLC LNDISP 11/27/2012 Historical
388244 Oral Communication None Oral Com 11/27/2012 for Molycorp Minerals LLC LNDISP 11/27/2012 Historical
388134 Oral Communication None Oral Com 11/06/2012 for Molycorp Minerals LLC LNDISP 11/06/2012 Historical
387562 Oral Communication None Oral Com 09/12/2012 for Molycorp Minerals LLC LNDISP 09/12/2012 Historical
387328 Oral Communication None Oral Com 08/09/2012 for Molycorp Minerals LLC LNDISP 08/09/2012 Historical
387074 Notice of Violation None NOV 06/08/2012 for Molycorp Minerals LLC LNDISPOTH 06/08/2012 Active
384029 Oral Communication None Oral Com 02/10/2012 for Molycorp Minerals LLC LNDISP 02/10/2012 Historical
384026 Oral Communication None Oral Com 03/29/2012 for Molycorp Minerals LLC LNDISP 03/29/2012 Historical
382505 Oral Communication None Oral Com 12/15/2011 for Molycorp Minerals LLC LNDISP 12/15/2011 Historical
382499 Oral Communication None Molycorp Minerals LLC Spill (12/8/2011) LNDISP 12/08/2011 Historical
382364 Oral Communication None Molycorp Minerals LLC Spill (11/28/2011) LNDISP 11/28/2011 Historical
382362 Oral Communication None Molycorp Minerals LLC Spill (11/1/2011) LNDISP 11/01/2011 Historical
382062 Notice of Violation None NOV 10/27/2011 for Molycorp Minerals LLC LNDISP 10/27/2011 Historical
381973 Oral Communication None Molycorp Minerals LLC spill ( 10/10/2011) LNDISP 10/24/2011 Historical
381972 Oral Communication None Molycorp Minerals LLC Spill (10/9/2011) LNDISP 10/10/2011 Historical
380390 Staff Enforcement Letter None SEL 07/20/2011 for Molycorp Minerals LLC LNDISP 07/20/2011 Historical
Total Enforcement Actions: 85
  
  
  
  
Expand/Contract Enforcement Actions
Regulatory Measures linked to Related Parties
Reg. Measure ID Organization Regulatory Measure Type Program Effective Date Status
388260 Aaron Case WDR WDRMUNIENROTH 11/07/2012 Active
377626 John Espinoza WDR LNDISPOTH 10/14/2010 Active
306717 John Espinoza WDR LFNONOPER 06/14/2006 Active
148001 John Espinoza WDR LNDISPOTH 09/14/2000 Active
133369 John Espinoza WDR LNDISPOTH 04/14/2005 Active
132920 John Espinoza WDR LNDISPOTH 10/14/2004 Active
Total Regulatory Measures linked to Related Parties: 6
  
  
The current report was generated with data as of: 10/31/2025
Regional Boards are in the process of entering backlogged data.
As a result, data may be incomplete.
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