Deshka River and Little Susitna River weirs flood

Following heavy rain fall events in the Matanuska Susitna Valley last week, rivers swelled with runoff and rose quickly. Salmon below weirs throughout the valley took advantage of the higher cooler waters to migrate upstream quickly, with some of the better daily salmon counts of the season occurring at Deshka River and Little Susitna River in the two days before flood waters overtopped both weirs and compromised additional counts for multiple days. The smaller more stable Jim Creek and Fish Creek drainages saw coho salmon migration counts spike, before rapidly falling again. The difference at Jim Creek and Fish Creek is that both of their weirs were operational throughout the entire period, and remained operational as the high water levels started to reside on Monday and Tuesday.

The Weir Counts: Deshka River Weir passed 536 coho on Wednesday August 27 and 1,451 coho on Thursday August 28, before water flooded over the weir on Friday August 29. Those two days of high coho counts were by far the highest coho counts of the year at Deshka River, with the next highest count being 185 coho back on August 19.

The spike in weir counts was a day later and not so dramatic at Little Susitna River. 259 coho passed Little Susitna River Weir on Thursday August 28 followed by 425 coho on August 29. The weir flooded on Saturday August 30. At Little Susitna River, the peak daily count of 605 occurred earlier in the season on August 12. Friday’s count of 425 was the second largest daily tally of coho of the season, and Thursday’s count of 259 coho was the fourth largest in 2025 at Little Susitna River.

At Jim Creek the daily coho count of 1,507 on August 28 was by far the highest weir count of the entire season. The second highest daily coho count on this system was 331 on August 3. After that one big day, Jim Creek counts dropped down sharply once again, with passage of 29 coho on August 29, an additional 181 coho on August 30, 22 coho on August 31 and 23 coho on September 1.

The Fish Creek coho surge of 357 coho on August 28 and 547 coho on August 29 included both the highest daily count of the season and the highest two consecutive daily total of the season. Before that surge 7 coho passed the weir on August 27 and after the surge 0 coho passed the weir on August 30.

Although the numbers varied at the different weir location, those rising counts illustrate how much upstream coho salmon migration can be influenced by water conditions. When I talked with Alaska Department of FIsh and Game (ADF&G) Area Sportfish Management Biologist, Samantha Oslund, on Tuesday she mentioned that Deshka River Weir had been damaged and that high water had kept the weir submerged — so it would be difficult to get it back in operation for a while— if at all this year.

Samantha mentioned the situation was better at Little Susitna River, where the weir appeared to be undamaged, and the water level had already dropped enough to where department staff may be able get it operation in short order (higher than normal water can still cause complications). Oslund had hoped to have both Deshka River and Little Susitna River weir operational as soon as possible to measure if there was any additional significant number of coho migrating upstream at each of those locations. Normally weir operations at both locations have run through the end of August or into September (to be counted as a full season).

In recent years salmon counts have been interrupted on any increasing basis by high water events at both Deshka River and Little Susitna River. However, Palmer ADF&G office staff attempted some adaptive management in 2025, moving Little Susitna River Weir to a shallower and wider section of river — about 7 miles upstream from where it had been situated since 2013. Moving the weir to the new location meant that it was not operational during most of the king salmon migration, with moving and installation completed on the evening of July 23, 2025. While Little Susitna River Weir was operational for most of the coho salmon season in 2025, this recent high water event, during a much drier than normal August, was the only water level that even remotely threatened the Little Susitna River coho count this year. In addition, it is good to know, that even with the sharp rise in water level and with some trees and logs floating downriver, the weir appears to have maintained its location — without being damaged or having portions blown downriver by the high water and debris.

A few early coho may have passed the new Little Susitna River weir site, before the weir was installed and counting coho in 2025. For example: 314 coho had passed the weir at its old location through July 23 in 2024, only 10 coho had passed the weir through July 23 in 2023, 0 had passed the weir by July 23 in 2022, and 69 had passed the weir through July in 2022.

High Water/Challenging Stream Fishing Conditions

When I asked Samantha if she knew of any Mat-Su Valley locations that might continue to provide some reasonable coho salmon fishing options this week, she mentioned that the coho runs were wrapping up, and with the high water, fishing success would likely be limited. Later in the day on Tuesday I drove over to 3 Rivers Fly and Tackle in Wasilla and asked Saul the same question. He mentioned that coho fishing had been relatively good in the Talkeetna River drainage before the high water, but that the river flows had exploded to extremely high levels in the Talkeetna River following the rain. In addition, following water of the entire Susitna River drainage, by regulation, switched to artificial lures only starting on September 1. It would appear, as mentioned in last week's column, that Mat-Su Valley salmon fishing is about over for the season. Weir counts at Fish Creek and Jim Creek will continue for a while, and anglers may get an idea about how regularly and in what numbers coho may be migrating through the lower part of those systems by checking Fish Counts on the ADF&G website.

Saul mentioned that 3 Rivers Fly and Tackle was still doing a considerable amount of business, but that most anglers were now purchasing trout fishing gear, and that fishing in streams would likely be good — dependent upon water levels and clarity. He’d also heard reports of anglers having good luck pursuing northern pike in lakes, and heard of good trout fishing in a couple stocked lakes near Wasilla. There will also be late-run coho available down south on the Kenai River through October, although high water at times, may make salmon catching more challenging at that location as well.

With the salmon fishing winding down in the Mat-Su Valley, I will likely be writing less about fishing locations as fall progresses, with my intent to more thoroughly cover the fisheries regulation process.

Good Luck and Fish On!

Andy Couch guides Mat-Su salmon fishing charters https://fish4salmon.com/ , is a member of the Matanuska Valley Fish & Game Advisory Committee, and the Matanuska-Susitna Borough Fish and Wildlife Commission, however, statements / opinions in this column are his own, unless expressed otherwise.