Water rights often decide what a ranch in Fergus County is worth and how much hay and grass it can grow. Before you buy, lease or irrigate ground here, check the Fergus County water rights tied to it with the tools below. For current snowpack, drought and cattle movement, see the Fergus County, Montana page; statewide rules are at the Montana DNRC water rights site.
Water Rights & Land Ownership
Fergus is the geographic and historical heart of central Montana cow country — the largest county in the state, anchored by Lewistown at the foot of the Judith Mountains. The Judith River and its tributaries drain north to the Missouri; the Musselshell headwaters drain south and east. With nearly 17,000 active water rights, Fergus has more recorded rights than any of the other central counties — most of them ranch-purpose surface diversions and stock rights on small creeks.
This page brings together the two state tools that answer the practical questions on any Fergus County property: DNRC WRQS for the water-rights record, and the Montana Cadastral for parcel ownership and the 17-digit geocode that links the two.
Active rights count pulled live from DNRC WRQS on 2026-06-01. Fergus spans eight DNRC basins: 41R, 41S, 41T, 41Q (Judith / Missouri side) and 40A, 40B, 40C, 40EJ (Musselshell side).
How these tools work together
- Find the parcel in the Cadastral — search by owner or address, click the parcel, copy the 17-digit geocode.
- Pull the water rights in WRQS — paste the geocode under “By geocode / PLSS”.
- See it on the map in WaterMapper — diversions, ditches, places of use in context.
Fergus County Watershed Map
The Judith River drains the central highlands north to the Missouri; Big Spring Creek runs through Lewistown into the Judith; the Musselshell headwaters drain the southern Snowy Mountains east toward Petroleum County. The Moccasin and Judith Mountains break the northern half of the county into Judith Basin / Big Spring drainage and Box Elder / McDonald Creek drainage.
Search Fergus County water rights
- Water right format:
- 41R 12345 00 (Judith) · 41T (Judith trib.) · 40C (Musselshell main).
- Primary basins:
- 41R Judith River main · 41T Judith tributaries · 40C Musselshell · 40A/B Musselshell headwaters. Margin: 41Q, 41S, 40EJ.
- Big Spring Creek note:
- One of MT’s largest cold-spring systems — substantial groundwater interaction with the surface right. GWIC well logs are particularly useful here.
- DNRC regional office:
- Lewistown Regional Office, 406-538-7459 (covers Fergus, Judith Basin, Petroleum, Musselshell, Wheatland, Golden Valley).
- Clerk & Recorder:
- Fergus County, 406-535-5242.
Irrigated Acres — USDA Census
Fergus County reported 20,032 irrigated acres in the 2022 USDA Census of Agriculture, up from 16,250 in 2017 — a change of +3,782 acres (+23.3%). These are acres that actually received irrigation in the census year, not all land equipped for irrigation.
Source: USDA 2022 Census of Agriculture, Table 10 (irrigated land, acres). See the Measuring Montana Moisture overview →
Quick links
- Honest Cattle Water Rights hub (statewide)
- Montana Cadastral (full screen)
- DNRC WRQS
- DNRC WaterMapper
- MBMG GWIC
Data sources: Montana DNRC Water Rights Database, Montana State Library / DOR Cadastral & ORION, Montana Bureau of Mines and Geology GWIC. Active rights count pulled live from the DNRC WRQS Feature Service. Informational only — for legal, engineering, or survey purposes consult official records directly.