What’s Gone Wrong With Hat Creek?

Last Tuesday, a mob of biologists, hydrologists, CalTrout staff, CalTrout founders and others toured Hat Creek’s Carbon Bridge stretch, and with so much scientific brainpower and historical knowledge in tow, those of us willing to listen learned a lot about the causes driving Hat Creek’s unhappy decline.

In the 1970s, Hat Creek became California’s first Wild Trout water, and accounted for the newly formed CalTrout’s first major win. (A lot of the people who made that happen — names like Richard May, Jim Adams and others — were on this tour.)

In the early 80s — at a time when fish counts were in the 6,800 fish per mile range — a plug of sediment started moving through Hat Creek.

Eventually, it decimated the aquatic vegetation, reducing bug populations and speeding the flow.

Meanwhile, invasive Muskrats burrowed under the banks, collapsing them, leaving behind a wider, shallower Hat Creek.

And yes, other bad things happened.

Fish populations plummeted. And fishermen stopped fishing Hat Creek in droves.

That’s the simple story. (Learn more in the video below.)

The good news is the sediment plug (visible in the upper reaches of Hat Creek in aerial photos as early as 1979) has largely passed the Carbon Stretch, and we’re seeing some small vegetation growth in the upper reaches.

Hat Creek Tour

One of the groups touring Hat Creek.

Much remains to be done, and we’re putting together an article and a video about CalTrout’s extensive Hat Creek restoration plan (courtesy CalTrout’s new videomeister Mikey Wier, whose hiring is a story unto itself — look for it soon).

Back with more on Hat Creek soon.

–Protect & Restore, CalTrout.


  1. Keith Barton says:

    Might I recommend making use of all that fire killed timber below the 299 bridge? Dropping a couple dozen tree trunks in the creek would offer a couple of decades of holding water – as well as egress to the creek for anglers without waders (which would give the insects a bit of a breather from all those wading feet, and give the creek a breather from all those potential invasives on all them feet).

    The rocks you helicoptered in at such great expense were too small to materially affect the fast water below the park, with an abundance of dead, flame-scorched decidous trees lining the creek, you’ve got a cheap source of shade and reintroduction of precious decayed plant matter for shade and forage.

    Just sayin’ is all …

    • CalTrout Staff says:

      Apparently the desirable laydowns are the trees with the root balls still attached, which can be difficult to move. Still, those are part of the recovery plan.

  2. Greg Kennedy says:

    Looking forward to the video and more knowledge. My brother Kris and I were talking the other day as to why there are not more big fish in Hat Creek. Having grown up on spring creeks on the East-side our heart goes out the this special stream!!!

    • CalTrout Staff says:

      We’re working on the video and the article, both of which contain a lot more detail about the recovery plan.

  3. jerry k says:

    It would’nt hurt to close Hat creek to waders one year at least, to get the bugs back.

    • CalTrout Staff says:

      In the Carbon stretch (and below), the biologists didn’t seem to think wading anglers were a big problem; the vegetation was going away for other reasons.

      We didn’t look too hard at the Powerhouse Riffle if that’s the stretch you’re talking about.

      • Wayne thompson says:

        Has anyone looked at the effect, if any, that the barrier has had?

        • CalTrout currently coordinates a technical review team, which we call the Hat Creek Resource Advisory Committee (Hat RAC). This group includes but is not limited to the CA Dept. of Fish and Game (DFG), the UC Davis Center for Watershed Sciences, the State Water Board, US Forest Service, PG&E, and others. In short, the Hat RAC believes that the barrier has been effective over the last 50 years in reducing the upward migration of non-game fish from Lake Britton into the Hat Creek Wild Trout Area. In 2010, DFG also assessed the potential unintended consequence of the barrier to block large trout from accessing the Wild Trout Area for spawning and habitat utilization. DFG surveyed in spring and fall to see if large trout could be observed holding/staging below the barrier. DFG ultimately determined that the number of trout staging below the barrier was inconsequential and therefore, modification of the barrier was unnecessary.

  4. Chris Ames says:

    What was the source of the “sediment plug” ? Why won’t it happen again?

    • CalTrout Staff says:

      I’m going to get Drew Braugh to answer these questions in more detail. What I gleaned from the Hat Creek tour is that the source of the sediment plug isn’t known for sure, though it wasn’t Flume Rd (blamed by many) which is estimated at only 5%-7% of the total amount.

      There was some thinking that PG&E’s attempts to solve the sinkhole issues that surfaced (or sank, depending on your perspective) after they’d moved the dam at Baum Lake caused some of the problem. They apparently attempted fill in the sinkholes, and that material might have found its way into Hat.

      Those efforts have ended and Hat is currently transporting less sediment than it’s capable of, so while no one can guarantee it won’t happen again, evidence suggests a recurrence — based on the same source of sediment — isn’t likely.

    • Greetings Chris,

      Spring Rivers Ecological Sciences (regional consultant) began studying the Hat Creek sediment slug in the early 90’s.

      In 1999, they made a few conclusions: 1) approximately 50-80,000 tons of sediment entered river sometime in the early 80’s (Kondolf, 1994) 2) by 1998, sediment at Carbon Bridge had decreased by 1-2 feet (meaning sediment is moving through system) 3) only 5-7% of the total sediment load (2,500 tons) can be accounted for (the vast majority of sediment is unaccounted for) 4) the Flume Road washout accounted for only 240 tons (less than 1% of total, not 5-7% as Tom suggested above) and 5) one hypothesis is that sediment load originated from sinkholes near Baum Lake Dam and the upper Hat 2 Bypass Reach.

      Support for Sediment Hypothesis:

      The Spring Rivers consultants found that sinkholes and lava tubes connect Baum Lake and the upper Hat 2 Bypass Reach to the Hat Creek Wild Trout Area. Apparently, some of these sinkholes began to collapse in the 1950’s (about the time of the relocation of Baum Lake Dam). Our best hypothesis at this point is that those sinkholes, over time, carried sediment into the Wild Trout Area. But unfortunately, nobody has been able to link the existing sediment load to a specific source and time.

      The good news?

      Hat Creek is currently transporting more sediment through the Wild Trout Area (WTA) than total inputs below Power House 2. In other words, more sediment is leaving the WTA then entering. One common misconception is that Hat Creek, with it’s low gradient and spring creek flows, cannot transport sediment adequately to flush the system. In reality, Hat Creek has high volume, constant flows that transport efficiently the low-density, sandy volcanic sediment produced by the watershed. Consequently, we really don’t think dredging is necessary. Moreover, the existence of a California Fully Protected Species (DFG code 515, rough sculpin) makes dredging politically and legally impossible at this time.

      I’m hopeful this clarifies a few issues. Look for more info/media on our website soon.

      Best regards,
      Andrew Braugh

      Hat Creek Project Manager

  5. Greg Ginsburg says:

    I have been fishing in the area for more than 30 years and have seen the decline. It seems the same thing is happening on the Upper Fall River perhaps for similar reasons. Clearly muskrats are a problem in both places but the loss of aquatic plants is quite evident in many areas too. Is there something that can be done to replenish the aquatic vegetation in areas that is has disappeared? Would dredging select areas be of benefit as well?

    • CalTrout Staff says:

      Again, Drew will have to speak to the similarities between Fall River and Hat Creek, though I know sediment was a major player in both.

      Fall is also suffering from an invasive species (Eurasian Milfoil) and controlling that explosion is an issue.

      Dredging Hat and Fall is probably a non-starter; both hold an endangered sucker fish, and in the case of Hat, there simply isn’t enough dredgeable material left.

      Thanks for showing up and asking questions; I hope we can get some better answers for you soon.

      • Greg Ginsburg says:

        I have seen a lot of the Eurasian milfoil. Is it responsible for forming mats at choke points such as the tubes on Spring Creek that can obsruct flow? There was a plan to introduce a beetle (weevil) to eat it. Did that ever get started and if so, what have the effects been thus far? Other than crowding out native plants, how does the milfoil negatively impact trout? It would seem it would provide great habitat for aquatic insects and as such enhance trout food availability.

      • Greg,

        Good observation: Hat Creek and Fall River both suffer from sediment supply issues. On both rivers, sediment supply issues over the last couple of decades have likely altered the natural assemblages of aquatic plants.

        In the Fall River, Eurasian watermilfoil (EWM) appears to be the primary beneficiary of changes in sediment supply. Unfortunately, we still don’t know the measurable impact of sediment supply on EWM in this particular system. Additionally, we really don’t know the measurable impact of EWM on the Fall River’s unique cold-water fishery. With that said, anecdotal evidence from local guides and fishermen certainly suggests that the abundance and diversity of macro-invertebrates has suffered since the outbreak of EWM in the early 2000’s. Moreover, existing scientific literature from around the country also discusses the potential negative impact of EWM on sensitive cold water fisheries (see Newman and Biesboer, 2000).

        CalTrout and Fall River Conservancy are currently exploring options for restoring native aquatic vegetation and macro-invertebrate abundance on both the Fall River and Hat Creek. In Fall River, we’re working with USDA on a pilot program that would gauge the effectiveness of a biological control (milfoil weevil) in balancing out the native vs invasive ratio of EWM to native aquatic plants (you raise a good point about EWM actually providing habitat for fish and bugs, but we’re confident that native assemblages and diversity are better overall). This pilot program is scheduled to start late June of this summer. In Hat Creek, CalTrout is working on a restoration design that includes replanting 6.3 acres of native vegetation in the riparian corridor throughout the Wild Trout Area (more info on the way).

        If you send me an email at dbraugh@caltrout.org I can send you a few published papers that talk about the ecological impact of EWM on cold-water fisheries. I can also discuss the bio-control plan in more detail. Thanks for your interest!

        Andrew Braugh

  6. Thankfully, a number of the previous comments on Hat Creek look beyond the specious preoccupation with yet another environmental bete noir – in this case The Evil Sediment Plug. If we are going to expend the angst, if not the scientific resources, to solve fishery problems, then just once why can we not look at things systemically? And, if we are going to look at things systemically, let us remember, as Herr Heisnenberg admonishes us, that we are indeed in the picture. Yes, that may even mean closing Hat Creek to all those well-heeled waders, and yes — rage, rage against the dying of the light — establishing a lottery system for angling access.

    • Shel,

      Great post! Did Heisenberg fly fish? Nice job bringing theoretical physics into the conservation equation. “We have to remember that what we observe is not nature herself, but nature exposed to our method of questioning” (Heisenberg, 1958). Perhaps for this reason, taking anglers off the water is always a tough one for us to come to terms with. Yes, as a group, we anglers suffer dreadfully from anthropocentrism. Yet we care deeply about the places that we fish because these rivers define us. Here’s the thing: anglers are likely not the root cause of Hat Creek’s illness. If they were, we’d be the first to say so (like we did in 1968 when CalTrout helped change the fishing regulations from a 10 fish limit to a 2 fish limit). Our approach is to restore ecological function. In other words, provide the river with what it needs to restore itself. Specifically, we need a functioning riparian corridor, in-stream habitat/cover, and aquatic vegetation. Remember that Hat Creek is slowly but surely flushing excessive sediment naturally (we are seeing new aquatic vegetation at the tail end of the slug). But to your point, as part of our restoration design, we propose to restore and re-align the existing trail system and access points (parking lot) to reduce angler impact (erosion, high density access points, angler pressure, etc.). If at any point, scientific evidence suggests that anglers are the root cause of the fisheries decline, we will certainly work with the Department of Fish and Game to explore management options. Although I’m doubtful they would support a permitting system, we can certainly start a discussion. Thanks again for the great post; keep them coming!

      Andrew Braugh
      Hat Creek Project Manager


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