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Wyoming · Wyoming Basin · #524
Sweetwater County, Wyoming
In the high desert basin of southwestern Wyoming where the Green River cuts south toward Flaming Gorge, Sweetwater County mines the world's largest deposit of trona - the natural soda ash mineral that ends up in glass, detergents, and baking soda - while sitting above oil and gas formations that add a second energy economy to its already unusual industrial profile.
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Office: Sweetwater County Office of Emergency Management (SC-OEM) – embedded within the Sweetwater County Sheriff’s Office | Director: Judy Roderick, 731 C. Street, Suite 131, Rock Springs, WY 82901, (307) 922-5371 | Non-emergency dispatch: (307) 875-1400 or (307) 362-6575
Services: Works closely with local fire departments, law enforcement, Regional Response Teams, Search & Rescue, National Weather Service, public health, and area hospitals; follows the standard five-phase emergency management model
Roads & Utilities
ROADS & TRANSPORTATION
Roads: I-80 serves both Rock Springs and Green River, the county’s two largest cities (Green River is the county seat), 12 miles apart
Transit: No dedicated fixed-route county transit identified; confirm current regional options directly with the county
Business & Permits
BUILDING & PERMITS
Office: Sweetwater County Land Use Office – 80 W. Flaming Gorge Way, Suite 23, Green River, WY 82935 | (307) 872-3914 or (307) 922-5430 | Fax: (307) 872-3991 | Land Use Director: (307) 872-3914
Services: Building permits, driveway/access permits, and environmental health septic permits for unincorporated Sweetwater County; well permits go through the Wyoming State Engineer’s Office; electrical wiring permits through the state
Notes: Cities of Rock Springs and Green River maintain their own SEPARATE building permit departments – confirm whether your property falls under city or county jurisdiction.
Veterans Services
VETERANS SERVICES
County VSO: Sweetwater County Veterans Service Office – Green River, WY
Libraries
LIBRARIES
System: Sweetwater County Library System – 3 main libraries (Rock Springs, White Mountain, Green River), 6 rural branches (Bairoil, Farson, Granger, Reliance, Superior, Wamsutter), and the Community Fine Arts Center
Main Branch: Sweetwater County Library, Green River – 300 N 1st East, Green River, WY 82935 | (307) 875-3615 | Fax: (307) 872-3203 | Hours: Mon–Thu 10 AM–7 PM, Fri 10 AM–5 PM, Sat 12–5 PM (closed Sun)
Services: The system began when residents of both Rock Springs and Green River independently worked to bring libraries to the region; today it operates one of the most extensive rural branch networks in Wyoming
Parks & Recreation
PARKS & RECREATION
Key Assets: Sweetwater County is genuinely home to the WORLD’S LARGEST TRONA DEPOSIT – the Green River Basin holds an estimated 127-134 billion tons of trona (natural sodium carbonate), with over 40 billion tons economically mineable using current technology; at current production rates, Wyoming’s trona reserves are projected to last well over 2,000 years; discovered accidentally in 1938 during oil and gas exploration by Mountain Fuel Supply Company, the deposit formed from the evaporation of ancient Lake Gosiute; today, mines in Sweetwater County produce roughly 90% of the entire United States’ supply of trona and about 25% of world production, refined into soda ash used in glass, baking soda, detergent, paper, and toothpaste manufacturing; the region is genuinely known as the “Trona Capital of the World”; the county also encompasses part of the Flaming Gorge Reservoir, Wyoming’s LARGEST RESERVOIR, and Expedition Island in Green River, the actual launch site of Major John Wesley Powell’s historic 1869 and 1871 expeditions down the Green and Colorado Rivers; the region’s mining boom historically drew colorful outlaw figures including Butch Cassidy and Calamity Jane; the Sweetwater County Historical Museum, housed in a former post office in Green River, documents this layered history spanning coal mining, railroading, fur trading, Native American cultures, the Pony Express, and the 1885 Rock Springs Chinese Massacre
Notes: Sweetwater County’s genuine, world-record status as home to the largest trona deposit on Earth – supplying the vast majority of America’s soda ash – is an extraordinary and well-documented piece of natural resource history.
GIS & Maps
GIS & MAPS
GIS Portal: Sweetwater County GIS/MapServer – accessible via sweetwatercountywy.gov
Parcel Search: Sweetwater County Assessor
Addressing/911: Coordinated through Sweetwater County Office of Emergency Management
Animal Services
ANIMAL SERVICES
Facility: Sweetwater County Animal Control (Sheriff’s Office division) – (307) 875-1400 or (307) 922-5321
Services: Works in conjunction with several area shelters designated for impounded animal care, including the Green River Animal Control Shelter (50 East 2nd North, Green River, WY), the Rock Springs Animal Control Shelter/Rock Springs Animal Control ((307) 352-1455 for lost pet reports), and the Red Desert Humane Society (310 Yellowstone Road, Rock Springs, WY), a nonprofit providing shelter, care, and adoption services
Notes: Animal control also coordinates with state livestock officers on livestock-at-large, abuse, and rural patrol matters.
Environmental & Waste
ENVIRONMENTAL / WASTE MANAGEMENT
Environmental Complaints: Wyoming DEQ – deq.wyoming.gov; Rock Springs Landfill also serves the county
Notes: Contact Sweetwater County, the City of Rock Springs, or the City of Green River directly for current refuse collection and recycling program details.
NOTES
Sweetwater County genuinely holds the world’s largest trona deposit – earning the region its real title as the “Trona Capital of the World” and supplying roughly 90% of the entire nation’s soda ash. All contact information above was sourced from official county, city, library, and shelter pages as of this writing; phone numbers and hours should be reconfirmed directly with the relevant office before a visit.
About Sweetwater County
Sweetwater County has one of the most unusual economic profiles of any Wyoming county. The Green River Basin contains the world’s largest known deposit of trona – a naturally occurring sodium carbonate mineral – and the mines operated by Solvay, Tronox, and Genesis Energy produce about 90% of the world’s natural soda ash, which goes into glass manufacturing, detergents, paper, and food products. The trona economy has given Sweetwater County a stable industrial base separate from oil and gas that has provided economic continuity through petroleum price swings.
Rock Springs and Green River are the twin cities of the county – Rock Springs the larger commercial center, Green River the quieter county seat on the Green River. Sweetwater County’s history includes the labor violence of the 1885 Rock Springs massacre, in which Chinese coal miners were attacked by white miners, 28 were killed, and the federal government reluctantly sent troops to restore order – one of the most disturbing episodes of anti-Chinese violence in American history. Flaming Gorge Reservoir, extending across the Wyoming-Utah border, provides boating, fishing, and recreation in one of the most dramatic canyon-country settings in the region.
All Services
Browse every category and topic available for this county.
Wyoming assesses residential property at 9.5% of market value. Mineral and industrial property carries higher assessment rates. Property owners may appeal to the County Board of Equalization (July 1 deadline). Wyoming has no income, estate, or inheritance tax.
Courts & Legal
Courts & Legal
SENIOR SERVICES
Sweetwater County Senior Center
333 Broadway, Rock Springs, WY 82901
Phone: (307) 352-1440
Senior transportation, Meals on Wheels, caregiver support, and long-term care counseling for Sweetwater County residents.
Senior Services
Sweetwater County Senior Center
333 Broadway, Rock Springs, WY 82901
Phone: (307) 352-1440
Senior transportation, Meals on Wheels, caregiver support, and long-term care counseling for Sweetwater County residents.
Marriage & Vital Records
Marriage licenses, divorce records, and birth & death certificates are handled by the following office(s):
COUNTY CLERK
80 W Flaming Gorge Way, Green River, WY 82935
(307) 872-3730
CLERK OF DISTRICT COURT
80 W Flaming Gorge Way, Green River, WY 82935
(307) 872-3960
Genealogy
County-level record sources
Sweetwater County Clerk of District Court, Green River (probate case files – see Probate section above); Sweetwater County Clerk’s Office (separate office) for recorded deeds, small-estate affidavits, and summary distribution decrees.
Local societies
No dedicated Sweetwater County genealogical society was confirmed in available directories.
Probate & Estate
Losing someone and having to deal with courts and paperwork at the same time is hard. This section won’t make that easier, but it should tell you what to expect, what it costs, and where to go – so at least you’re not walking in blind.
Where to go
Sweetwater County Clerk of District Court (Third Judicial District) PO Box 430, Green River, WY 82935 (307) 872-3820
Sweetwater County is in Southwest Wyoming, the largest county in Wyoming by land area, home to Rock Springs and Green River, county seat Green River. Wyoming has NOT adopted the Uniform Probate Code – it runs its own probate framework under Title 2 of the Wyoming Statutes (“the Wyoming Probate Code”). Probate is filed with the DISTRICT COURT for the county where the decedent lived, administered day-to-day by that county’s Clerk of District Court. Note that Wyoming counties have TWO separate elected clerk offices relevant here: the Clerk of District Court (handles probate case filings) and the County Clerk (a separate office that records deeds, small-estate affidavits, and summary distribution decrees).
Step 1: figure out which path applies
Wyoming Statutes Title 2 governs probate.
Small Estate Affidavit (Wyo. Stat. §2-1-201) – available when the decedent’s entire estate, including personal property (and, per a 2025 update, mineral interests), does not exceed $400,000 (increased from $200,000 effective July 1, 2025, via 2025 Enrolled Act 85/SF0104), less liens and encumbrances. This estate must consist ONLY of personal property (no real estate) for the pure affidavit-to-County-Clerk route. Available 30 days after death; skips court entirely – filed with the County Clerk, who issues a certified copy the claimant presents to banks or other asset holders.
Summary Distribution (Wyo. Stat. §2-1-205) – for small estates up to $400,000 that DO include real property. Requires filing an Application for Decree of Summary Distribution with the District Court (not just the County Clerk); requires 2 consecutive weeks of published notice; the court issues a decree that gets recorded with the County Clerk to clear title.
Full Probate Administration – required for estates exceeding $400,000 or otherwise not eligible for the small-estate or summary paths. File a Petition for Probate with the Sweetwater County District Court.
Step 2: filing for administration
File a Petition for Probate with the Sweetwater County District Court.
Notice must be published for 3 consecutive weeks (Wyo. Stat. §2-7-201).
Once a personal representative is appointed, creditors have 3 months from the date of first publication to file claims (Wyo. Stat. §2-7-703).
The personal representative pays valid debts and expenses, then distributes remaining assets to heirs/beneficiaries.
Close the estate with a final accounting to the District Court.
Wyoming courts are increasingly moving toward e-filing; check with the Clerk of District Court for current e-filing requirements for pro se (self-represented) filers.
Wyoming does NOT have a statutory percentage fee schedule for personal representatives or attorneys – unlike many states. Fees must be “reasonable” and are subject to court approval (Wyo. Stat. §§2-7-803, 2-7-804).
A bond may be required (Wyo. Stat. §§2-3-102, 2-3-111) unless waived by the will or all beneficiaries.
Wyoming does NOT impose a state estate tax, inheritance tax, or state income tax – one of the most tax-friendly states in the country for estate administration. Only the federal estate tax may apply, with a $15,000,000 per-person exemption for 2026.
Probate filings, estate administration, and guardianship matters are handled by the following office(s):
Public Safety & Arrests
Arrest records, inmate search, and law enforcement services are handled by the following office(s):
SHERIFF
80 W Flaming Gorge Way, Green River, WY 82935
(307) 872-6560
Elections & Voting
Voter registration, polling locations, and elections information are handled by the following office(s):
ELECTIONS
(307) 872-3730
Health & Human Services
Offices & Contacts
Health services, social services, and assistance programs are handled by the following office(s):
Public Health
Sweetwater County Public Health, 1902 Foothill Blvd, Rock Springs, WY 82901
(307) 352-6813
DFS Office
Sweetwater County DFS Office, 1200 College Dr, Rock Springs, WY 82901
(307) 352-3200
Public Health Information
PUBLIC HEALTH
Office: Sweetwater County Public Health – Rock Springs/Green River, WY
Services: Immunizations, WIC, environmental health, vital records
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Last verified June 2026
County Facts
County Seat: Green River
Population: 41,500
Tier: 4
Inmate Services
Care Packages
Send care packages to inmates in Sweetwater County facilities via Amazon.
