Sienna Mendez
Sienna Mendez is a Mental Health Counselor in Seattle, WA, registered under NPI 1003623950.
Getting there
Here is what surrounds this office in Seattle, based on OpenStreetMap data collected Oct 11, 2026. Parking is available about 522 ft away at Ballard Medical Center Parking. There is EV charging 0.20 mi from the office — useful if you are driving in from out of town. The nearest transit stop is 728 ft away, served by Northwest Market Street & 20th Avenue Northwest. A pharmacy sits 0.24 mi from the entrance (Safeway), which helps if you leave with a prescription. If you arrive early, there is a coffee shop 402 ft away.
Getting here and what is nearby
Coffee Artemis Coffee Co. 229 ft ~1 min
5507 17th Avenue Northwest, Seattle 98107
Mo-Su 08:00-19:00
Convenience 7-Eleven 209 ft ~1 min
1550 Northwest Market Street, Seattle 98107
24/7
Parking Keelson Apartments Residential Parking Lot 254 ft ~1 min
Northwest 56th Street
Coffee Mighty-O Donuts 389 ft ~2 min
1555 Northwest Market Street, Seattle 98107
Mo-Fr 07:00-14:00; Sa-Su 07:00-15:00
Coffee Poke Square 402 ft ~2 min
Parking Urbana Parking Lot 434 ft ~2 min
Restaurant NUA Thai 461 ft ~2 min
Restaurant Monkey Bridge 501 ft ~2 min
Parking Ballard Medical Center Parking 522 ft ~2 min
Barnes Avenue Northwest
Transit Northwest Market Street & 15th Avenue Northwest 566 ft ~3 min
Restaurant Papa John's 567 ft ~3 min
1500 Northwest Market Street, Seattle 98107
Mo-Th 09:45-24:00; Fr-Sa 09:45-02:00; Su 09:45-24:00
Transit 15th Avenue Northwest & Northwest Market Street 621 ft ~3 min
Convenience Food Mart 618 ft ~3 min
Gas station Chevron 669 ft ~3 min
Pharmacy Walgreens 667 ft ~3 min
5409 15th Avenue Northwest, Seattle 98107
Mo-Su 06:00-22:00
Transit Northwest Market Street & 20th Avenue Northwest 728 ft ~3 min
Gas station Chevron 722 ft ~3 min
Gas station Safeway Fuel Station 853 ft ~4 min
EV charging 1,001 ft ~4 min
EV charging 0.20 mi ~4 min
EV charging 0.20 mi ~4 min
Grocery Town & Country 0.21 mi ~5 min
1400 Northwest 56th Street, Seattle 98107
07:00-22:00
Grocery Safeway 0.22 mi ~5 min
1423 Northwest Market Street, Seattle 98107
Mo-Su 06:00-23:00
Pharmacy Safeway 0.24 mi ~5 min
1423 Northwest Market Street, Seattle 98107
Mo-Fr 09:00-13:30,14:00-21:00; Sa-Su 10:00-13:30,14:00-18:00
Hotel Ballard Inn 0.29 mi ~6 min
Hotel Hotel Ballard 0.29 mi ~6 min
Hotel Hotel Ballard 0.29 mi ~6 min
Convenience Ballard Stop 0.34 mi ~7 min
2220 Northwest Market Street, Seattle 98107
Mo-Th 09:00-22:00, Fr,Sa 09:00-24:00, Su 09:00-20:00
Grocery QFC 0.41 mi ~9 min
5700 24th Avenue Northwest, Seattle 98107
Mo-Su 05:00-01:00
Distances are straight‑line estimates — walking routes may be longer. Hours and phone numbers can change; call ahead to confirm.
Credentials and Medicare
| Licence | State | Specialty |
|---|---|---|
| MHCA.MC.700878937 | WA | Mental Health Counselor primary |
This provider holds licence MHCA.MC.700878937 issued in WA. A licence number in NPPES reflects what was filed at registration — it does not confirm the licence is still active today.
This NPI does not appear in the PECOS Medicare enrolment file. Providers who do not bill Medicare — or who bill only through a group's enrolment — will not appear here. It is not a sign of any problem with the registration.
What Mental Health covers
Definition to come... NUCC Health Care Provider Taxonomy, code 101YM0800X
The taxonomy records how the provider classifies their own practice. It does not confirm which conditions they currently treat, whether they are accepting new patients, or which insurance they take — call the office for that.
Full NPPES record
An NPI-1 identifies a single person. It stays with the clinician for life, even if they move practice or change state, which is why the address on file can lag behind where they actually work today.
| NPI | 1003623950 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Dec 13, 2024 |
| Last updated | Apr 21, 2026 |
| Status | Active |
| Sole proprietor | No |
| Practice address |
5608 17TH AVE NW STE 1668 Seattle, WA 98107 (206) 672-3202 |
Number check
How the check works, step by step
Every NPI carries a Luhn check digit — the same scheme used on credit cards. CMS prefixes the number with 80840 before computing it, which marks it as a US health identifier.
| Digit | 8 | 0 | 8 | 4 | 0 | 1 | 0 | 0 | 3 | 6 | 2 | 3 | 9 | 5 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 0 | 0 | 3 | 3 | 2 | 6 | 9 | 1 |
Sum = 50 · next multiple of 10 = 50 · check digit = 0 · actual last digit = 0
A valid check digit only means the number is well-formed. It does not mean the provider is licensed, active, or in good standing — those are separate questions answered by the sections above.