| Business | Phone |
| Long Island Horticultural 3059 Sound Ave, Riverhead 11901 | (631) 727-3595 |
| Cornell Cooperative Extension 423 Griffing Ave, Riverhead 11901 | (631) 727-7850 |
| County Business Certificates 310 Center Dr, Riverhead 11901 | (631) 852-2037 |
| East End Methadone Clinic 300 Center Dr, Riverhead 11901 | (631) 852-2680 |
| Honorable Alan D Oshrin 210 Center Dr, Riverhead 11901 | (631) 852-1759 |
| Honorable Anthony R Corso 210 Center Dr, Riverhead 11901 | (631) 852-1640 |
| Honorable Arthur G Pitts 210 Center Dr, Riverhead 11901 | (631) 852-2174 |
| Honorable Cf Cacciabaudo 210 Center Dr, Riverhead 11901 | (631) 852-2670 |
| Honorable Elizabeth Emerson 235 Griffing Ave, Riverhead 11901 | (631) 852-2781 |
| Honorable Gary J Weber 210 Center Dr, Riverhead 11901 | (631) 852-2176 |
| Honorable Harry E Seidell 210 Center Dr, Riverhead 11901 | (631) 852-1764 |
| Honorable John J Jones 210 Center Dr, Riverhead 11901 | (631) 852-1429 |
| Honorable Lester E Gerard 235 Griffing Ave, Riverhead 11901 | (631) 852-2370 |
| Honorable Michael F Mullen 210 Center Dr, Riverhead 11901 | (631) 852-2166 |
| Honorable Patrick Henry 235 Griffing Ave, Riverhead 11901 | (631) 852-2325 |
| Honorable Peter Fox Cohalan 235 Griffing Ave # 308, Riverhead 11901 | (631) 852-2395 |
| Honorable Ralph T Gazzillo 210 Center Dr, Riverhead 11901 | (631) 852-2583 |
| Honorable Stephen Braslow 210 Center Dr, Riverhead 11901 | (631) 852-1431 |
| Suffolk Cnty Horticulture Lab 246 Griffing Ave, Riverhead 11901 | (631) 727-4126 |
| Suffolk Cnty Horticulture Lab 423 Griffing Ave, Riverhead 11901 | (631) 727-4126 |
| Suffolk Cnty Supreme Ct-Record 235 Griffing Ave, Riverhead 11901 | (631) 852-2414 |
| Suffolk Cnty Training & Edctn 200 Center Dr, Riverhead 11901 | (631) 852-2505 |
| Suffolk County Appeals Bureau 200 Center Dr, Riverhead 11901 | (631) 852-2469 |
| Suffolk County Consumer Affr 300 Center Dr, Riverhead 11901 | (631) 852-2053 |
| Suffolk County Courts 210 Center Dr, Riverhead 11901 | (631) 852-1437 |
| Suffolk County Center 310 Center Dr, Riverhead 11901 | (631) 852-1400 |
| Suffolk County Center Public Acce 310 Center Dr, Riverhead 11901 | (631) 852-2040 |
| Suffolk County Ecology Office 300 Center Dr, Riverhead 11901 | (631) 852-2077 |
| Suffolk County Home Economics 246 Griffing Ave, Riverhead 11901 | (631) 727-7850 |
| Suffolk County Homicide Bureau 200 Center Dr, Riverhead 11901 | (631) 852-2575 |
| Suffolk County Jurors Comm 225 Griffing Ave, Riverhead 11901 | (631) 852-2300 |
| Suffolk County Legislature 423 Griffing Ave, Riverhead 11901 | (631) 852-3200 |
| Suffolk County Legislature 633 E Main St, Riverhead 11901 | (631) 852-3200 |
| Suffolk County Marine Ext 3059 Sound Ave, Riverhead 11901 | (631) 727-3910 |
| Suffolk County Marine Resource 300 Center Dr, Riverhead 11901 | (631) 852-2082 |
| Suffolk County Micrographic 310 Center Dr, Riverhead 11901 | (631) 852-2018 |
| Suffolk County Narcotics Bur 200 Center Dr, Riverhead 11901 | (631) 852-1880 |
| Suffolk County Passport Office 310 Center Dr, Riverhead 11901 | (631) 852-2099 |
| Suffolk County Public Adm 300 Center Dr, Riverhead 11901 | (631) 852-1752 |
| Suffolk County Public Adm Suffolk County Ctr, Riverhead 11901 | (631) 852-1753 |
| Suffolk County Real Property 300 Center Dr, Riverhead 11901 | (631) 852-1550 |
| Suffolk County Surrogate Center 320 Center Dr, Riverhead 11901 | (631) 852-1745 |
| Suffolk County Torrens-Land 310 Center Dr, Riverhead 11901 | (631) 852-2031 |
| Suffolk County Ucc 310 Center Dr, Riverhead 11901 | (631) 852-2038 |
| Suffolk County Veterans Svc 300 Center Dr, Riverhead 11901 | (631) 852-1410 |
| Suffolk County Warden Office 100 Center Dr, Riverhead 11901 | (631) 852-2283 |
| Suffolk County Women's Svc Suffolk County Ctr, Riverhead 11901 | (631) 852-1603 |
| Suffolk County Youth Bureau Suffolk County Ctr, Riverhead 11901 | (631) 852-2694 |
| Suffolk Wastewater Management 300 Center Dr # S238, Riverhead 11901 | (631) 852-2100 |