In July I wrote about the feeling of coming home to the Middle Fork of the Eel River. In mid-August, I experienced my second river homecoming, this time to the Lost Duzen (a remote section of the Van Duzen River, major tributary to the Eel River, and home to a small population of summer-run steelhead). My field partner and I at CDFW initiated an annual dive survey on the Van Duzen River in 2011 to estimate the summer-run population size. I participated in the survey from 2011-2021 but have missed the past three years. I was therefore immensely grateful to return to a river that is like an old friend. 

This 19-mile stretch of colorful river canyon has lovingly been described as “roughs interspersed with a few gravel bars”. Massive hunks of chert, andesite, graywacke, slate and serpentine in a vast array of shades and hues beckon you to climb upon them. Luckily, that is required to make any forward movement down the river. As the day progresses and your body temperature is lowered from consistent snorkeling, the smooth, sun-baked rocks provide a thermal refugia for your chilled belly. 

The first night we camped alongside one of the main holding pools for over-summering adult fish. The water temperature was at the high end of their thermal tolerance, so there was minimal leaping activity, but we still had the pleasure of a few respectable splashes in the evening and early morning hours. Summer steelhead in the Van Duzen River tend to hold in a more limited number of pools than in other rivers in the region. There are around 120 pools that are dove every year, but we have only seen adult steelhead in 10% of them. This results in entire days where not a single adult anadromous fish is seen. There are numerous deep, thermally stratified pools in the void which appear to be perfectly suitable habitat. Numerous theories have evolved to explain this phenomenon. Barrier proximity, cold seeps, herding mentality, inter-annual scouring and depositional flows, to name a few. The confusion lies in the fact that these are all factors in other basins as well, where fish are more widely distributed.

The answer may lie in the reality that the fish we see are a very small remnant of what existed in the Van Duzen pre-contact. While this is true in the other summer-steelhead basins in the region, the Van Duzen watershed is less protected than some of the other basins such as the Middle Fork Eel River, New River or Clear Creek. It has a major highway running along most of its length, primarily private land ownership (some large ranches, but many smaller parcels with development and water withdrawals), extensive clear-cut logging, low elevation headwaters with little current snowmelt and a highly erosive nature. Additionally, cold water storage in the Lost Duzen comes in part from upslope fens (similar to bogs, but less acidic), unique in the area, that were heavily mined for potting soil in the early 2000s.

Summer steelhead counts from elsewhere in northern California have happily been significantly higher than average this summer. This was not the case on the Van Duzen where we only saw 61 adults (the 15 year average is 110). We are still pondering why the Van Duzen isn’t following the hopeful rebounding (albeit slightly) pattern we have seen elsewhere in the region. The adult summer steelhead we did see in the Van Duzen were large and powerful. Still making their ancient migration to a colorful canyon that welcomes home its old friends.