Will Detroit Lake and other Willamette Reservoirs Fill? Maybe Not, But Don’t Panic

Have you driven by one of the Willamette Reservoirs lately and wondered if they will actually fill for summer recreation?  Good question!

Now let me point out that it’s perfectly normal to drive by Detroit Lake, Green Peter, Lookout Point, Cougar, & Hills Creek reservoirs in winter time and see them extremely low.  That’s all the extra space left each fall for rainy-season flood events.  The storage built into these reservoirs keeps us from seeing regular flood events in the Willamette River system (including Eugene, Salem, & Portland!) each winter.

Here’s a graph with a bunch of lines…it’s for Detroit Lake (east of Salem):


First, ignore the entire bottom half of the chart and focus instead on the thick red line on the upper part.  That’s the “control curve” showing, in a perfect world, where officials want the level of the lake to be during each part of a normal year.  Notice the lake is normally kept “full” from around May 1st to September 1st, then the level is dropped to the winter minimum by December 1st each year.  It is kept there (if possible) through February 1st, then filling begins.  That gives the Corp 3 months to “empty” reservoirs in the fall and 3 months to fill them in the late winter and spring.  In the case of Detroit Lake the lake level varies about 113 ft. from “empty” to “full”.

Now look at the blue line…that’s the actual level over the past 12 months.  Notice last summer the lake dropped a bit lower than preferred in the 2nd half of summer and then followed the “curve” more or less through the fall and early winter.  As a meteorologist it’s interesting to note the wintertime spikes when heavy rainfall suddenly fills the reservoir.  In late December the level jumped about 40′ in a very short period of time!  February 1996 must have been crazy!  On that blue line you can also see that right after a heavy precipitation event lots of water is poured downriver to quickly bring the level back down to where it should be in winter.

Two things I’ve noticed in the past few months:  They started allowing it to fill earlier than normal this year (mid/late January) since it was obvious ridging was going to stick around that point with its dry weather.  Then you can see how the filling is going much more slowly this year.  A week from now (May 1st) the lake would typically be “full”.  Not this year!  Looks like it is running about 45′ below the curve right now, which means as you drive by it’s only as full as it would typically be in late February or early March.

So will it fill?  Most likely NO.  But that doesn’t mean no boating! Here’s a forecast from the Army Corps of Engineers from about a week ago:


The purple line on the left side is the past and then future forecasts (and levels right now) begin at the dotted line.  The blue line is the most likely scenario, assuming normal precipitation/conditions over the next month or two.  The red line is the line in which there’s only a 5% chance it’ll get above that.  Looks like officials think it’s most likely the lake will top out around 1450’…about 13-14′ below full pool.  What does that mean for boating?

Take a look at (ONE MORE) chart for the past 7 days:


This one shows all the boat ramp elevations.  There is one that’s available all year long…the low water ramp.  But the current level is still at least 20-55 feet below all the other ramps.  The good news is that most of those ramps should be available this summer according to the forecast levels up above.  You’re just going to have to wait a bit longer to get on the water this year!

I didn’t look into any forecast for other reservoirs…although you can find all the info on the Army Corps of Engineers Willamette Basin Web Page.  You can see all the reservoirs are well below normal in this graphic:


So don’t panic if you have party plans on “the lake”…there WILL be some water to play on!

Chief Meteorologist Mark Nelsen

53 Responses to Will Detroit Lake and other Willamette Reservoirs Fill? Maybe Not, But Don’t Panic

  1. Jeff says:

    Seems to be the driest Spring I’ve experienced living in Portland. Is there a drier April on record? I live in St. John’s and was a bit shocked to see the city flushing so much water last month. I also noticed many days it looked like the clouds were about to burst followed by a short, heavy, and very localized downpour. Anyway, looking forward to the summer. Hope we get some rain though.

  2. Tyler Mode in Battle Ground says:

    A little bit of down slope wind here this afternoon bumped my temperature up to 83.7. It certainly didn’t help that the morning started at 50.

  3. David B. says:

    Mid-70s up this way this afternoon. Feels like summer, but it’s not going to last.

  4. WhiteEagle - Garden Home / SW Portland says:

    1450’…typo, right?? Looks more like 1560′. Great post, though!

  5. Jason Hougak says:

    Mt. Hood looks amazingly awesome!

  6. schmit44 says:

    4/26/2015 Oregon (All) Temperature Summary

    High:69 at Grants Pass – Pa( 910 ft) & AGNESS2(247 ft) & MERLIN SEED ORCH(1144 ft) & PROVOLT SEED ORC(1180 ft)
    Low: 48 at Port Orford(0 ft)

    High:31 at HOWARD Mt Howard(8150 ft)
    Low: 4 at CROW FLAT (5172 ft )

    Largest Diurnal Change: 45 degrees
    Lorella (63/18 ) (4160 ft )

    Heaviest Rainfall:
    0.72″ at MEARES Cape Mear(1421ft)
    0.58″ at OCNSID Oceanside(22ft)
    0.56″ at HEBOWX Mt. Hebo(3160ft)
    0.44″ at CEDAR(2220ft)
    0.42″ at K7ZQU-7 Santiam(4790ft)
    0.39″ at TILLAMOOK(11ft)
    0.37″ at PACCTY Pacific C(253ft)

  7. …Remember when people used to take pride in their command of the english language….when people used to actually research bits of information before spouting gibberish about weather and geologic processes that don’t exist?…when people actually learned from the educational years that one’s childhood was spent in?…it seems to be a dying art in this country to actually put forth coherent thoughts that are readable and worthy of intelligent discussion….

    • Farmer Ted says:

      Well said.

      “Well, we wish we were happier, thinner and fitter,
      We wish we weren’t losers and liars and quitters
      We want something more not just nasty and bitter
      We want something real not just hash tags and Twitter

      It’s the meaning of life and it’s streamed live on YouTube
      But I bet Gangnam Style will still get more views
      We’re scared of drowning, flying and shooters
      But we’re all slowly dying in front of f…..g computers.”
      ~Lyrics from “Scare away the dark” ~Passenger~

    • Boring Oregon says:

      Said the guy on the computer…

    • Boydo3 N. Albany elev. just under 500' says:


    • Farmer Ted says:

      Don’t you just love it Boydo3! awesome video and message. I really don’t think B.O. gets it, but that’s ok (probably hits too close to home….boring???) I spent my whole day out working with plants, dogs, wildlife, my fellow man and sunshine too, like I do most every day.

    • pappoose in scappoose says:

      I really like it, Boydo!

  8. WEATHERDAN says:

    60 and cloudy in Salem this afternoon. Looks brighter off to our South. Might hit 80 on Monday. Rest of the week looks so so. Mostly in the 60,s to lo 70,s with a few on and off showers. Peace.

  9. MasterNate says:

    Looks like our pm showers are about to become pm steady rain. As per radar.

  10. Jason Hougak says:

    Biggest tsunami will be when the 3 Gorges Dam in China bursts.

  11. schmit44 says:

    4/25/2015 Oregon (All) Temperature Summary

    High:65 at BLALOK( 277 ft) & CW2551 Medford(1491 ft) & MERLIN SEED ORCH(1144 ft) & BOARD(290 ft) & ECHO(683 ft) & Ontario Municipa(2188 ft)
    Low: 50 at NERRS METEOROLOG(9 ft)

    High:28 at HOWARD Mt Howard(8150 ft)
    Low: 11 at CROW FLAT (5172 ft )

    Largest Diurnal Change: 31 degrees
    HEREFORD (52/21 ) (3599 ft )

    Heaviest Rainfall:
    0.80″ at NORTH FORK(3120ft)
    0.78″ at DW4118 Sandy(1250ft)
    0.78″ at CW6318 Welches(1283ft)
    0.73″ at TROUT CREEK(2268ft)
    0.70″ at SOUTH FORK BULL(2630ft)
    0.70″ at MT HOOD TEST SIT(5400ft)
    0.69″ at EW6654 Rhododend(1411ft)
    0.62″ at DW0380 Sandy(1600ft)

  12. Lee Wilson says:

    In the mean time I have this thing hanging around.
    What kind of cloud is it?

    It looks like it is trying to rain, but the twin never hits the ground it like it is getting sucked back up in it.

  13. MasterNate says:

    Was that volcanic eruption in chili large enough to effect weather or even climate on a global scale this year?

    • Lee Wilson says:

      I wonder that too, and if Mt Severest Goes…….well lets hope that quake didn’t. Trigger that..looks like lots of volcanoes going ..all I know is we here in the Pacific NW. Are sitting on several time bombs.

      We will be the ones being interviewed.. Only the Headlines will read “Massive Quake Kills thousands, interrupts exports and imports, and sends Tsunami. To Japan and…to ….parts of Portland Oregon .

      It is false hope to hope it won’t happen, and a false belief that it will not occur.

      I am extremely surprised at thequake that hit was so shallow.

      Let us hope it has not began the process for an Everest Eruption.

    • Dringus says:

      ….a tsunami down the Willamette? Or…are the waves gonna go over the coast range???

      Well at least we’re not fearmongering or anything.

    • Lee Wilson says:

      I am curious though, for real, if a Tsunami can travel up rivers?

      hmm going to kill 2 birs with one stone before battery dies,

      caught a nice immage of Hail that looks like a beam of Light.
      Storm just misses us: http://youtu.be/X1EBZj5EsuM

    • Dringus says:

      Yeah they can, just not to nearly the same scale of devastating effects.

    • Boydo3 N. Albany elev. just under 500' says:

      Lee..you really need to do the spell check thing. It hurts to read your posts.
      And do a little research. MT. EVEREST IS NOT A VOLCANO! It can’t erupt!!!

    • …let us hope prune hill doesnt erupt….

    • Boring Oregon says:

      @lee I really doubt that a tsunami could travel up rivers that far and create problems in Portland. I’m sure that some parts of the Columbia River will be effected but definitely not the Willamette River.

    • W7ENK says:

      Mt. Everest is not a volcano, as the Himalayas are not a volcanic mountain range, they’re a tectonic uplift range made up of mostly sedimentary and metamorphic rock. They formed over eons of uplift from India pushing into and underneath Asia. Imagine taking a sheet of paper, holding it flat, and jamming it into a wall. Mt Everest would be the highest wrinkle in that sheet of paper.

      As for a tsunami coming up the Columbia, yes, it is entirely possible, and could be potentially devastating. According to a special on NOVA, after the 2011 Japan earthquake, the resulting tsunami created a standing backpressure wave that travelled 50km up the Kitakami River, gaining almost 2,000ft of elevation before flooding out the isolated mountain community of Kahoku, around the lake that served as the River’s headwaters. That lake is now brackish.

    • W7ENK says:

      That may not be the correct name of the river…

      Also, I forgot to add: by some estimates, a surge of back pressure could travel up the Columbia all the way to Bonneville Dam, and up the Willamette to the falls in Oregon City — albeit slight that far inland — but no one knows for sure.

    • Farmer Ted says:

      Stop the presses! Almighty W speaks again. What would it be like without you?

    • W7ENK says:

      Uhmmm… hello there? o_O

  14. There WILL be some water to play on!

  15. Ted Berry says:

    All the better for stump viewing.

  16. schmit44 says:

    4/24/2015 Oregon (All) Temperature Summary

    High:66 at Ontario Municipa(2188 ft)
    Low: 51 at Rye Valley(I-84(2230 ft) & CW8876 Williams(1640 ft)

    High:29 at CW7477 Lostine(7002 ft)
    Low: 18 at CROW FLAT (5172 ft )

    Largest Diurnal Change: 28 degrees
    Wasco Junction ( (59/31 ) (1100 ft )

    Heaviest Rainfall:
    1.60″ at NORTH FORK(3120ft)
    1.00″ at BLAZED ALDER(3650ft)
    1.00″ at RED HILL(4400ft)
    0.90″ at GREENPOINT(3200ft)
    0.83″ at Mount Hood Meado(5249ft)
    0.82″ at CEDAR(2220ft)
    0.80″ at SOUTH FORK BULL(2630ft)
    0.80″ at HEBOWX Mt. Hebo(3160ft)
    0.80″ at MT HOOD TEST SIT(5400ft)
    0.78″ at LOG CREEK(2800ft)
    0.78″ at SOUTH FORK(2257ft)

  17. Vinnybob says:

    If we made it through the summer of 1977, we’ll make it through this summer.

    • Brian Leroy says:

      This year is nothing like 77 so stop assuming, we much wetter then that year, get ur facts straight there’s no drought outlook from CPC either. u have no idear man.

    • Ted Berry says:

      Hey LeRoy, sometime ya gotta put down the booze, mellow out a bit and get some sleep.

  18. Wendy-Silverlake, Wa says:

    Just had some nice window rattling booms here with insane amounts of rain and hail. Exciting!!

  19. schmit44 says:

    4/23/2015 Oregon (All) Temperature Summary

    High:72 at LAKE OWHEE AND O(2400 ft)
    Low: 50 at ROWEWS(104 ft)

    High:33 at Timberline Lodge(6001 ft)
    Low: 9 at CROW FLAT (5172 ft )

    Largest Diurnal Change: 49 degrees
    FOSTER FLAT (63/14 ) (5000 ft )

    Heaviest Rainfall:
    0.80″ at NORTH FORK(3120ft)
    0.70″ at HOLLAND MEADOWS(4900ft)
    0.60″ at BIG RED MOUNTAIN(6250ft)
    0.60″ at SUMMIT LAKE(5600ft)
    0.60″ at RAILROAD OVERPAS(2750ft)
    0.60″ at SALT CREEK FALLS(4000ft)
    0.52″ at LOG CREEK(2800ft)

  20. WEATHERDAN says:

    Showery in Salem this afternoon. Temps in the mid 50,s. Looking forward to a big warm up starting on Sunday. Next Friday we are in May and weather conditions look a little above normal for temps and mainly dry. It’s nice that the Cascades got a little late season snow. But we needed feet and not a few inches. Still that picture of snow falling at skibowl on tv yesterday sure looked nice. Normal highs in Salem in May start out at 65 on the 1st and rise to 71 on the 31st. Meteorological Summer starts in 38 days. Peace.

  21. W7ENK says:

    Annual Detroit Lake Fishing Derby has been advertised all winter long as being May 15-17.

    They have 3 weeks to get the water level high enough to reach the end of the boat launches and float their marinas. At this rate, I don’t see that happening.

    Word is, you could walk down into the old (usually submerged) town of Detroit as of last weekend.

  22. runrain says:

    What about for watering lawns, etc. Are there going to be restrictions/concerns for that this year?

  23. Paul D says:


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