Wildfire affect on high lakes

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This topic contains 7 replies, has 5 voices, and was last updated by  Rich OConnell 2 months ago.

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  • #115160

    JOSHUA BURCK
    Participant

    With the Miriam fire about half a mile from Hell lake in the south cascades and 70% contained I have been watching the situation closely. Made me think of a few questions who has had lakes they like to visit in the wildfire areas this year or last few years? Also I could not find any studies on the web on fire impact on high lakes. I am sure it is complex from shade from trees and deadfall, bugs from the brush and amphibians for food, water temperature, and lake size must be a factor I’m sure to. Does anyone here have any experience on how a fire will affect a high lake?

  • #115161

    Brian Curtis
    Keymaster

    This is a great question. I sure don’t have any real answers. I could imagine a pulse of productivity getting washed into a lake after a fire. But I could imaging alternative scenarios, too.

  • #115913

    KGabriel
    Participant

    I, too, am interested in the impact of the recent fires. Phantom Lake in the South Fork of the Tieton has fire go right above it with little or no impact that I could discern on the lake. I visited 3 Sombreros Lake in the Crow Creek drainage that was much more drastically burned up to by Norse Peak fire and could perceive little impact there, either. I’m eager to get further down into the Crow Creek drainage to Anna and Crescents Lakes and Hell Lake as well this summer. I was nervous about getting into the Norse Peak fire area only a year removed from the fire for fear of deadfall, and although common sense should be exercised, I’m less nervous. I’m under the impression that the Miriam Fire did not burn up to or over Hell Lake, but I’m eager to see it. Shouldn’t be much longer for the PCT to be snow free around White Pass.

  • #115965

    Jim Mighell
    Participant

    I have been interested in this question for several years since my recent experience in the recent fires that raced through the Limebelt area of Okanogan county. I am very familiar with some of these lakes, after having provided fish many years ago at the request of prominent TrailBlazer George Lewis and his friendship with a restaurant owner at Ballard – I have been allowed access to some of these lakes ever since, to fish for “adequate” fish.
    Last spring I fished one of those lakes after wading through ash to my knees on the access road, and fished several areas of the lake with no success whatsoever – my assessment was – NO FISH — that after fast fishing for a variety of sizes to 4 lb shortly before the fire. The lake has been stocked by a local private hatchery every year.
    I have tentatively formed a hypothesis that the huge amount of ash that fell on the lake formed a layer of “caustic ash” otherwise known as LYE, that formed, and slowly descended to the bottom, thus killing any fish that came in contact with that lye layer by burning the gills instantly. I believe that same scenario could affect any lake under a fire.

  • #115976

    JOSHUA BURCK
    Participant

    I think that theory would make sense Jim, however one thing that I get hung up on with that theory are the lakes in the Margaret Backcountry by St Helens. After the eruption none of these lakes were stocked with fish according to my research, and these lakes are in the blast area. Several of the lakes have Brook trout that lived through the eruption and still exist in their respective lakes. Given there are a ton of factors that play into this, obviously fire and volcanic eruptions are very different. Also maybe some species of fish are more hardy to survive something like this than others.

  • #115977

    Brian Curtis
    Keymaster

    Joshua, the lakes in the blast zone were ice covered when the mountain erupted. That saved the fish from the initial blast. There was a productivity spike as nutrients were washed into the lakes and for a while the fish grew larger. But I believe that in the lakes were the reproducing populations survived they have all settled back to their pre-blast stunted states.

  • #115979

    JOSHUA BURCK
    Participant

    Brian, Wow I completely forgot that those lakes would have been frozen during the blast, I was around yet during the blast so its easy to forget. Considering that what Jim stated makes a lot more sense.

  • #115980

    Rich OConnell
    Keymaster

    I found this interesting article about wildfires and its effects on water chemistry.

    The effects of wildfire on the water chemistry of dilute, acidic lakes in southern Norway

    Summary

    The most severe chemical conditions in wildfire affected surface waters occurred during some of the first post-fire rain events, but the amount of rain in relation to the hydrological status of the catchment prior to these events, and lake residence time, are decisive factors regarding when the most extreme water chemical conditions arise in surface waters affected by wildfire.

    During the first post-fire hydrological episodes, strong acid anions as Cl− but primarily SO4 2−, are mobilized significantly faster from terrestrial to aquatic systems compared with base cations (ΣBC), which means that the acid neutralizing capacity (ANC) of lakes decline. For lakes with low pre-fire ANC values, significant drops in ANC down to very low negative values might occur, with subsequent increase in [H+] and toxic inorganic Al [Ali] to levels potentially harmful to aquatic life. In lakes with higher pre-fire ANC values, the drop in ANC during the first post-fire period is too small to cause severe acidification, and therefore harmless to aquatic life. Normal ANC values seem to be reestablished relatively fast in wildfire affected lakes, often within the first post-fire year.

    After the extreme, post-fire water chemical peak, the main mobile anions (Cl− and SO4 2−) decreased faster than ΣBC. This combined with increase in TOC should imply a potential increase in ANC with time after fire in wildfire affected lakes. However, at the same time, the continuous dilution effect back to pre-fire levels, might counteract this potential ANC increase. This might explain why no ANC increase was seen in five of the six wildfire affected lakes, from one year after the fire and the next three post-fire years.

    Increases in nutrients, N and P, and decreases in TOC in surface water during the initial post-fire period, followed by a gradual decrease in N and P and increase in TOC during the next post-fire years, have also been seen in surface waters from other wildfire impacted areas.

    The water chemistry in the wildfire affected lakes in the Mykland area, had almost returned to pre-fire conditions 4.5 years after the wildfire. Thus, in this area of Norway, with significant reductions in acid deposition during the last decades, with [SO4*] reduction by 75–88 % in lakes from 1980 to 2011 (Schartau 2012), the most severe water chemical episodes, are again primarily driven by sea-salt events, directly linked to hydrologic episodes, directly as a result of heavy rain, or indirectly during snow melt as the sea-salt episode(s) are “accumulated” in the snowpack.

    Hydrological regime, topography, geology, fire intensity, fraction of catchment burnt, lake morphometric conditions such as catchment-to-lake area ratio and lake residence time, are key factors for the variations in water chemical response in wildfire affected lakes.

    Live Free or Die

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