Water Rights & Land Ownership
This page brings together two essential public tools for understanding land and water in Sweet Grass County: the Montana DNRC Water Rights Query System (WRQS) and the Montana Cadastral land ownership database. Together, they let you search water rights by owner or source, view parcel boundaries and ownership on a map, and connect the two — every parcel in the Cadastral carries a 17-digit geocode that links directly to water rights in the DNRC database.
Sweet Grass County spans 1,855 square miles with approximately 2,800 active water rights across three primary DNRC basins: 43Q (Yellowstone River main corridor), 43BJ (Boulder River, tributary of the Yellowstone), and 43BV (Sweet Grass Creek). The Boulder River is the county’s most important irrigation source — it runs entirely within the county from its headwaters in the Absaroka Range to its confluence with the Yellowstone at Big Timber, and carries some of the most senior irrigation rights in the region, many dating to the 1880s. The West Boulder and East Boulder are separate drainages; the Stillwater Mining platinum-palladium operation on the East Boulder holds significant industrial water rights. In low-flow years, the Boulder is over-appropriated and junior rights may be curtailed.
How these tools work together
- Find your parcel in the Cadastral map below — search by owner name, address, or zoom to the location and click the parcel.
- Note the 17-digit geocode shown in the parcel details.
- Search water rights using the WRQS search tool — select “By geocode / PLSS,” paste the geocode, and click “Search WRQS.”
- View on the map — the interactive watershed map shows major diversions, rivers, and irrigation areas across Sweet Grass County.
Montana Cadastral — Sweet Grass County Parcels & Land Ownership
The Montana Cadastral is the state’s official parcel mapping system, maintained by the Montana State Library and Department of Revenue. Every parcel in Sweet Grass County is mapped with owner names, addresses, assessed values, agricultural use classifications, tax districts, and geocodes. Public land (Custer Gallatin National Forest, BLM, state trust) appears as larger unsubdivided parcels — nearly a quarter of the county is publicly owned.
Tip: Zoom into Sweet Grass County (south-central Montana, around Big Timber). Click any parcel for owner info, assessed value, ag classification, and geocode. Copy the geocode, then scroll down to the WRQS search and paste it in the “By geocode / PLSS” field to find all water rights on that parcel.
What the Cadastral tells ranchers
- Parcel boundaries & ownership — verify legal descriptions and current owners when buying, selling, or leasing ranch land
- Agricultural classification — irrigated cropland, dryland hay, grazing — which directly affects property tax assessments
- Public land adjacency — identify Custer Gallatin National Forest and BLM land bordering your operation, critical for grazing allotments
- Geocode → water rights — every parcel’s 17-digit geocode links to the DNRC water rights database. This is the fastest way to find all water rights attached to a property
Water Rights Map & Search
The interactive map below covers the entire county — from the Yellowstone River corridor through Big Timber, south up the Boulder River valley to McLeod and the Absaroka Range, northeast to the Crazy Mountains, and east to the county borders. Click any diversion point for details.
About Sweet Grass County water rights
Sweet Grass County holds approximately 2,800 active water rights across basins 43Q (Yellowstone River main corridor), 43BJ (Boulder River), and 43BV (Sweet Grass Creek). The Boulder River carries some of the most senior irrigation rights in the region — many dating to the 1880s — and is over-appropriated in low-flow summers. The Stillwater Mining operation on the East Boulder holds industrial rights for platinum-palladium processing. Big Timber Creek, Sweet Grass Creek, American Fork, and Otter Creek support additional irrigated hay acreage in their respective valleys.
Search tips for Sweet Grass County
43BJ 12345 00Montana Cadastral ·
WRQS ·
WaterMapper ·
GWIC
Irrigated Acres — USDA Census
Sweet Grass County reported 42,129 irrigated acres in the 2022 USDA Census of Agriculture, up from 38,786 in 2017 — a change of +3,343 acres (+8.6%). These are acres that actually received irrigation that year, not all land equipped for irrigation.
Source: USDA 2022 Census of Agriculture, Table 10 (irrigated land, acres). Measuring Montana Moisture →
Quick links
- Montana Cadastral (full screen) — Montana State Library parcel & ownership database
- WRQS — Montana DNRC Water Rights Query System
- WaterMapper — DNRC interactive GIS map of diversions, ditches & waterways
- GWIC Mapper — Montana Bureau of Mines groundwater wells & well logs
- Sweet Grass County — county government & services
Data Sources
- Montana State Library / MT Department of Revenue (Cadastral & ORION database)
- Montana DNRC Water Rights Database
- DNRC Water Rights Query System (WRQS)
- DNRC WaterMapper / ArcGIS
- Montana Bureau of Mines and Geology (GWIC)
- NRCS Sweet Grass County program data
- Sweet Grass County Conservation District