Waterton River

The Waterton leaves the Waterton Lakes inside Waterton Lakes National Park and runs north about 80 km to the Belly River. Every river and stream in the park has been closed to fishing since April 1, 2024, so the fishing starts at the park boundary, about 2 km below the Waterton Park gauge. From there the river runs about 30 km through ranch country to the Waterton Reservoir, an irrigation reservoir built in 1964 by Hill Spring. Below the dam it carries on as a tailwater toward Glenwood and the Belly. The 2026 Alberta regulation table lists rainbow trout, westslope cutthroat trout, brook trout, brown trout and mountain whitefish both above and below the reservoir.

Read the Waterton Park gauge for the upper river. It measures what leaves the lakes, so the river rises later and falls more slowly than the freestones around it, and it runs clearer, because the lakes trap much of the silt. Runoff usually peaks in June, often above 50 m³/s (1,770 cfs), so the river is still high when the season opens on June 16. It drops through July, and from August into October it usually runs about 4 to 8 m³/s (140 to 280 cfs), low, clear and easy to cross at the tailouts. Expect the usual southern Alberta summer menu: stoneflies and caddis in July, hoppers and ants in August, and small olives in the fall. Below the dam the river runs on what the reservoir lets out, not on the weather. Outside a wet June, when the dam can spill, the Glenwood gauge usually sits around 3 to 7 m³/s (105 to 245 cfs) from July into the fall.

The rules split at the reservoir, so know which side you are on. Above it you may keep brook and brown trout from June 16 to August 31, and every rainbow and cutthroat goes back. Below it you may keep a rainbow or cutthroat over 35 cm (14"), and every brook and brown trout goes back. On both, every trout goes back from September 1 to the October 31 close. Most banks are private ranch land: reach the water at bridges and road allowances and stay below the high-water mark, or ask the landowner. The Waterton Reservoir Provincial Recreation Area at the dam is the one public base on the river, and Alberta Parks has closed its campground and day use for rebuilding until about late June 2027. Expect strong west wind most days, and in a hot, low summer the province can restrict fishing on ES1 streams to certain times of day, so check the advisories before a July or August trip.