Environment Canada in conjunction with the Water Survey of Canada provides Water Station Levels Across Canada. Manitoba Water Stewardship also provides weekly information through its River Conditions page. The City of Winnipeg posts water levels regularly for several sites within Winnipeg. This page provides a few common benchmarks as well.
I have collected levels from the Environment Canada Hydrometric Data page so I have a reference for paddling or poling. These are just a guide and should be checked for your own use ahead of time. Remember the difference of a few centimeters can be quite significant.
Assiniboine River at Headingley ~231.55 - good flow for easy playing (Moray St., Assiniboine Park, Kenaston - Omand Park) and getting past Assiniboine Park without hitting bottom. Just around 231.4-231.5 is good for moving water practice near Kenaston-Omand Park but a little low for other parts. The maximum level for poling at Assiniboine Park and west ~231.46. This is level is a little deep for poling further west but right at the bridge to the swifts (just west) is OK. Poling at 230.8m is almost perfect at Assiniboine Park.
Roseau River between hwy 59 and 218 (Dominion City station) 242.5 - this is good flow with some rapids not too high and not bony. I recently had a report that 241.6 is a good level so I guess between these marks should be fine. Check for 293.3 at Garenton (or higher). this measure goes with 241.6. I spent the day poling on the Roseau River at 240.4 - this was a little. Any lower would have been scraping more. I spent the day poling from the old ford at 240.82 - this level was fantastic for poling.
Pembina River at hwy 201 (near Windygates, or Pembina Valley prov park) a level of 337.220 (discharge 10.8m^3/s) is great for poling. It could be a little lower, but not too much. This is equiv to 392.78 at La Riviere. You can also check the North Dakota USGS Canoeing page for the Pembina River. They recommend at least 910cfs for canoeing at Walhalla this equates (roughly) to 337.6m at Windygates. The ND site recently was updated to indicate that canoeing at a level of 350cfs is possible. I would recommend paddling starting at La Riviere rather than starting 201 or 31 because of the current and distance to the US border. Note: if heading downstream from 201 you only have ~8km to the US border, there is no convenient egress so you have to paddle/pole back.
Souris River at Wawanesa with a level of 348.150 is good for poling. Much lower and there are sandbars, much higher and it will be too deep in several places. Even at this level there are a number of places that are too deep to pole and paddling becomes easier. Head upstream from #2 near Wawanesa or upstream from Mckellar Bridge (on 346).
The bridge at La Barriere park is just underwater on the La Salle River when the Red River at St. James Street Station is 226.7 (16.2 feet) or Below Floodway Control Structure is 228.2.
At 224.7 (just below the Floodway Control Structure) the La Salle can still just be paddled below the dam. It might be tricky close to La Barrrier as the river really does not back up that far from the Red.
Red River at St. James Street Station 224. This level means I can use my usual launching pad in Winnipeg without getting muddy ☺.
Whitemouth River (Dawson Rd to TC). I travel this section fairly often and usually check with the campground regarding levels (level 0.7-2 poling, 1+ canoeing). Alternatively look at Whitemouth River at Whitemouth for levels of 267.98 (3.0m3/s) or greater (268.2 corresponds to level 3 - limit for poling, but good for canoeing). There are a few places that might require a wade at level 1. I will pole upstream at this level 1. There is a small charge if you leave your car at the campground, you may be able to arrange a shuttle (to Dawson Rd crossing) for a small cost as well.
Birch River (near Prawda). The water level at 98.12 (discharge 4.4) is good for paddling with the current (July 31, 2016). I spent the day poling at 98.01 (Oct 1, 2022) and this level was pretty reasonable in most places. The sections between the riffles could be paddled at this level as well. I don't know what the zero level is for 98 but it is also provisional so don't count on it too much.
Netley Creek. Upstream from Hwy 9 (park at the Mallard Duck) is possible but there are a number of riffle structures through the golf course. There is a water level meter at hwy 8, when it was 224.23 there was wading through the golf course. When the level reads 226.5 a downstream run should be OK. The size and flow are similar to Seine (inside Winnipeg); is the potential for downed trees across and lots of beaver dams. There were surprisingly few downed trees/deadheads, I am wondering if there is snowmobiling in the winter and the creek is cleared (for safety) - snowman doesn't list. Downstream from hwy 9 to the Red is wide and open.
Brokenhead River (Green Bay Rd - where 45E crosses this is where the gauge is located as well) it is shallow for poling at 228.5 (try 228.6). I you would want it a little deeper for continuous paddling, headed downstream would be OK. Heading north near Norse 228.9 is nice for paddling but just right for Poling practice at the C1 rapids and swifts (no ledges thought). Starting at 435 the level is fine at this level at least through 82N (a fine day paddle).
Cooks Creek is quite a nice paddle from Hwy 44 to the East Selkirk Fire Station. Based on paddling July 17 and July 30, 2016. July 17 was difficult to paddle against, but possible, downstream was no problem except for some strainers. The meter reading below the diversion was 1.4m with a discharge of around 1.5m3/s (see video https://www.youtube.com/watch?v=ojylTeDCndU). July 30 was too low (0.9) but still fun - there were about 10 places where wading was required. My suggestion would be above 1.2m (0.8m3/s) and stopping around 2m as some bridges and other things might become an issue. Check what it looks like just downstream of hwy 59 for an idea of the overall level since this was the longest typical wade.
Boyne River (near Carmen) is quite a nice paddle. There is a riffle structure just east of town (49.509134, -97.956687), a dam on the west side (at the golf course), and a large riffle structure right in the middle (just east of Main St or Hwy 12). The riffle in the middle is more like a low-head dam and is difficult to spot from above. Water levels were measured at the Boyne River near Carmen (253.4m, 9.4m^3/s discharge), or Boyne River near Roseisle (1.32, 4.8m^3/s discharge). The Carmen station is downstream of the riffle structure so upstream may be better over the summer. The water level was good for paddling and I expected almost 50cm lower would still be fine as most of the day I couldn't touch the bottom with my paddle. You can put in your canoe near the east riffle structure - although the bridge is out, and just off 4th st SW (northeast side of footbridge). Access points that I have used: Riffle Structure (49.509134, -97.956687)), Bridge east of Carmen (49.505957, -97.978986), Bridge south of Graysville (49.501783, -98.160130), There is a pedestrian bridge at 49.501525, -98.006690 (off of 4th st sw) that has a walk down to the river.
Seine River, near La Broquerie, I accessed from 34N but there are a number of access points. The water level at Sainte Anne was 253.48 which was a good level for paddling. Much deeper it would be difficult to go against the current, I figure 25-30cm lower would still be OK. I expect the river in Sainte Anne or La Broquerie would be fine at this level. The river is narrow with periodic sweepers. Dropping in at St. Raymonds just south of Ste. Anne is possible but there are swifts just up (and down) stream of the bridge that would require poling. The next bridge to the south provides access and no swifts (upstream).
Seine River (inside Winnipeg). There is no water gauge inside the floodway which makes things a little difficult as the siphon under the floodway has an upper flow rate. The closest meter is at Prairie Grove, outside of the floodway. A level of 1.3m should be enough for most paddling, although a few spots with cement/rebar/rip-rap may be problematic along with riffle structures. Even lower than this the sections south of John Bruce, and RoyalWood Bridge may be deep enough for some distance.
I went poling July 1, 2017 on the Little Saskatchewan upstream from the closest bridge to Assiniboine River (Daly Bridge) to Kirkham's Bridge. The level was excellent for poling, any lower some rapids would have to be walked/waded, any higher the current might have been too much to get up some of the drops. The water level at the nearest measurement was: Little Saskatchewan, near Rivers level at 451.28 (discharge 5.9m3/s)
The Cypress River is often dry through the summer so I watched the hydrometric station near Bruxelles and took a guess based on prior years and summertime levels. It seemed that 100.5-100.8 (discharge of 2-4m3/s) would probably work. April 13, 2019 the levels were right at 100.8 so I took a chance. I poled and paddled upstream from the egress point north of Holland for a couple of hours. I ran into several barbed wire fences and decided to call it a day. My guess appeared to be good, I expect a little higher would be fine for coming downstream, it was just on the top end for poling. The station is a long way upstream so some interpretation will be required. If you are going downstream watch for fences strung across the river. The RM and conservation warned of spillways (low-head dams/culverts) and other obstacles. There were numerous strainers/sweepers as well to navigate around. The bridge on hwy 2 has been under construction for a couple of years and is not great for access but that should be cleaned up when finished. There is another egress point south of Cypress River where a local road crosses the river
Lake of the Woods Control Board provides water level data, updated each workday, for the Winnipeg River drainage basin.