Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of October 4, 2026.
NPIDirectory

Dr. William Sprague Trask IV, DO

Individual provider Anesthesiology Physician · NPI 1184706608

Dr. William Sprague Trask IV, DO practises Anesthesiology in Boulder, Colorado. Graduated from At Still University of Health Sciences, College of Osteo Med, Kirksville in 2006, 20 years ago. Practices with Boulder Valley Anesthesiology, PLLC, a 60-clinician group and accepts Medicare assignment. Licensed in Colorado and Washington.

Years since qualifying
20
Trained at
At Still University of Health Sciences, College of Osteo Med, Kirksville
Licensed in
CO, WA
In the registry since
2006
Specialties on file
3
What do these letters mean?
DO — Doctor of Osteopathic Medicine
A fully licensed physician, trained like an MD with additional musculoskeletal training. Equivalent practice rights in all 50 states.

See every abbreviation used in this directory →

Claim this listing Report a problem Suggest an edit

Practice location Address checks out

4747 Arapahoe Ave
Boulder, CO 80303-1131
Phone: (303) 415-2532
Fax: (303) 785-1725
Show map & directions

Directions in Google Maps · Apple Maps · OpenStreetMap

Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Anesthesiology Physician (primary) Taxonomy 207L00000X · Licence 49491 (CO)
Anesthesiology Physician Taxonomy 207L00000X · Licence OP60150344 (WA)
Anesthesiology Physician Taxonomy 207L00000X · Licence OL20000111 (WA)

Record details

NPI number1184706608
Entity typeIndividual (Type 1)
GenderMale
Credentials DO
Sole proprietorNo
NPI enumeratedOctober 20, 2006
Last updated in NPPESSeptember 14, 2026
Certification dateSeptember 14, 2026

Medicare enrollment

From the CMS Doctors & Clinicians file — this clinician is enrolled in Medicare.

Medicare specialtyANESTHESIOLOGY
Medical schoolAT STILL UNIVERSITY OF HEALTH SCIENCES, COLLEGE OF OSTEO MED, KIRKSVILLE
Graduated 2006 (20 years in practice)
Group practice Boulder Valley Anesthesiology, Pllc — 60 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount

Medicare patients and services, 2024

From the CMS Medicare Physician & Other Practitioners file for calendar year 2024. It counts Original Medicare patients only, so a practice that mostly sees Medicare Advantage or privately insured patients looks smaller here than it is.

Medicare patients218
Services billed 270 a service is one billed item, such as a visit, a test or a procedure
Average patient age74

Dollar amounts are not shown. What Medicare pays a practice is gross billings, before staff, premises and tax and including the cost of any drugs it administers, so it is not what a clinician earns.

Practises at

Facilities the CMS Facility Affiliation file lists for this clinician.

Colleagues at Boulder Valley Anesthesiology, PLLC

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 60 clinicians in the practice; 12 are shown here.

Other providers in Boulder