NPPES file of Aug 9, 2026

Doctors and health care providers in Clayton, CA

91 individual NPPES records list a practice address in Clayton, 502nd of 812 California cities. The largest group is addiction (substance use disorder) counselor: 34, 37% of the city's records, against 3% across California. Page 2 of 2.

CMS NPPES registry, file of Aug 9, 2026 · method · Verify with CMS →

Clayton in California

  • Rank in California502nd of 812 cities by records
  • Share of the state<0.1% of California's records
  • Specialties present25 or more taxonomy codes
  • Top three groups59.3% of all records

Compared with California as a whole, Clayton has 13.1× the state's share of addiction (substance use disorder) counselor records.

Providers in Clayton, alphabetically

  1. Heather Lesieur, PA-C, MS, MPHPhysician Assistant1891726972
  2. Christopher Lloyd, SUDRCAddiction (Substance Use Disorder) Counselor1891497939
  3. Jacob Lynch, DPTPhysical Therapist1912784695
  4. Sherman Mah, R.PH.Pharmacist1184995300
  5. Christina Mason, D.D.S.General Practice Dentistry1467576652
  6. Jennifer Mellin, AMFTMarriage & Family Therapist1700690765
  7. Alison Meyer, OTR/LOccupational Therapist1235517905
  8. Cliff MillsAddiction (Substance Use Disorder) Counselor1629273891
  9. Christine Mitry, RPHPharmacist1306309489
  10. Seong Kit Moore, PHARMDPharmacist1306711650
  11. William Morfeld, M.D.Internal Medicine Physician1306145107
  12. Chris Murray, RADTAddiction (Substance Use Disorder) Counselor1326563487
  13. Dana Nguyen, RPHPharmacist1982981163
  14. Douglas Novotny, PH.D.Clinical Psychologist1962548800
  15. Larissa Oberholtzer-Gallagher, RNCritical Care Medicine Registered Nurse1023607017
  16. Carlos PadillaAddiction (Substance Use Disorder) Counselor1710182977
  17. Ashvinbhai PatelPharmacist1114390481
  18. Zeenal PatelPharmacist1073987665
  19. James PerryAddiction (Substance Use Disorder) Counselor1669678330
  20. Randy Prado, RADTAddiction (Substance Use Disorder) Counselor1285303941
  21. Barbara RobertsAddiction (Substance Use Disorder) Counselor1215132477
  22. Emily Roberts, M.A. CCC-SLPSpeech-Language Pathologist1700314804
  23. Melissa SadlerAddiction (Substance Use Disorder) Counselor1245435403
  24. Charles Scalmanini, SUDCCAddiction (Substance Use Disorder) Counselor1518641638
  25. Garrett Schwab, SUDRCAddiction (Substance Use Disorder) Counselor1578379012
  26. Melissa Sidnam, M.A.Addiction (Substance Use Disorder) Counselor1306217898
  27. Anna SisonDentist1619141389
  28. Bonnie Slatkin, RDHAPDental Hygienist1518395060
  29. Lee SonkoPediatric Occupational Therapist1154212140
  30. David Spellman-Zimmerman, RADTAddiction (Substance Use Disorder) Counselor1063024701
  31. Alexander Sprague, MA, LPCCMental Health Counselor1407266158
  32. Michael Stevenson, SUDCCAddiction (Substance Use Disorder) Counselor1043929193
  33. Taha TahaPharmacist1346130465
  34. Siuping TangPharmacist1902364573
  35. Jana Tomsky, M.D.Family Medicine Physician1346308798
  36. Richard Townlin, PHARM.D.Pharmacist1235451444
  37. Victor Truong, D.D.S.General Practice Dentistry1295029163
  38. Dennis Wasco, MA, MFTMarriage & Family Therapist1427196344
  39. Nomel WashingtonAddiction (Substance Use Disorder) Counselor1669966479
  40. Brandon WoodardAddiction (Substance Use Disorder) Counselor1528449931
  41. Jason ZelisAddiction (Substance Use Disorder) Counselor1366967259

The largest California cities

  1. Los Angeles69,537
  2. San Diego52,937
  3. San Francisco38,143
  4. Sacramento33,083
  5. San Jose20,925

All of California →

How to read this directory

Clayton, California appears in the CMS National Plan and Provider Enumeration System with 91 registered healthcare providers spanning 25 or more distinct NUCC-taxonomy specialties. This count includes every individual clinician who has applied for an NPI and listed a practice address in Clayton - physicians, dentists, nurse practitioners, physician assistants, chiropractors, physical therapists, optometrists, psychologists, podiatrists, and every other credentialed provider type CMS tracks. It does not measure hospital beds, urgent-care capacity, or whether a given clinic is accepting new patients; it measures the pool of professionals with current NPI enrollment and a Clayton practice location on file. Every figure is drawn from the federal National Provider Identifier Registry (CMS NPPES) - more than 7 million providers, maintained since May 2007, with 2024 Medicare Part D data, and, according to CMS, can be searched, compared, and traced in our methodology.

The provider mix in Clayton is weighted toward Addiction (Substance Use Disorder) Counselor (34 clinicians, followed by Pharmacist with 15 and Dentist with 5). That distribution reflects how NPPES records specialty: providers self-select a primary taxonomy code, so a family physician who also practices geriatrics will show up under whichever NUCC code they registered first. Relative to California's population, Clayton reports roughly 0.2 providers per 100,000 residents using the state-level denominator, which is a rough proxy rather than a precise access-to-care measurement; the true catchment area of any {cityName} clinician extends beyond the municipal boundary.

Of California's most common specialties, Student in an Organized Health Care Education/Training Program is the most prominent one with no provider currently listing a Clayton practice address, a coverage gap Clayton patients typically fill by traveling to a larger nearby hub.

For Clayton patients, this directory is most useful as a starting shortlist. Important: PlainDoctor is a directory of publicly available CMS government data, not a review site, a ranking, or medical advice. NPPES data is self-reported and refreshed monthly; call the practice directly to confirm the provider is still there, accepts your insurance, and is taking new patients.

For informational purposes only; this directory is not medical advice and not a substitute for checking a license. See also: how to find a doctor and how to verify one.

Common questions

How many doctors are in Clayton, CA?

There are 91 registered healthcare providers in Clayton, CA, covering 25 or more specialties. This includes physicians, dentists, therapists, and other licensed providers.

What are the most common medical specialties in Clayton?

The most common specialties in Clayton are Addiction (Substance Use Disorder) Counselor, Pharmacist, Dentist, Behavior Technician, Marriage & Family Therapist. Addiction (Substance Use Disorder) Counselor has the most providers with 34.

Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov). Records are self-reported registrations, not licenses.

Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.