It’s become fashionable in progressive coastal cities to start planning for the reality of climate change, particularly sea level rise. Locally, Sound Transit says “the Supplemental Environmental Impact Statement (SEIS) for the Long-Range Plan update will consider the potential rise in sea level and localized flooding that may occur as a result of climate change based on GIS data currently available.” Although maps of the Seattle Archipelago are an interesting thought exercise, in the foreseeable future rising seas are likely to be much less dramatic. Nevertheless, plausible sea level predictions do have implications for Sound Transit’s long range plan.

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Sound Transit 1 and 2 rail lines will suffer little in the next hundred years or so, although the elevated Boeing Access Road section may become a causeway over water or frequent flooding. Although Seattle is fortunate to find most of itself at elevation, Sound Transit 3 and beyond face serious constraints. Hopefully, Seattle will allow thriving, dense neighborhoods to grow around those stations; if those station areas are under immediate threat, the value of the entire alignment is doubtful.

A wildly optimistic estimate as to when light rail might open to Ballard and/or West Seattle is 2030. A map I found that projects what the coastline might look like 50 years after that is at right.

A few immediate observations from this map:

  • An approach to West Seattle on or west of 1st Ave S is a little dicey.
  • Interbay is a terrible place to create a new neighborhood, suggesting an eastern approach to Ballard is more responsible.
  • The idea of a “Rainier Valley Bypass” via E. Marginal Way to speed up South Link trips seems bankrupt, in particular because it would likely come after Sound Transit 3.
  • South Sounder looks to be in pretty good shape; coastal North Sounder, not so much.
  • The Deep Bore Tunnel is not well-positioned, but its lack of futureproofing extends well beyond the sea level.

Link to Tacoma via Fife is also problematic:

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Predictions about the future are hard, and there’s no way to know if these will come to pass. The world could get serious about greenhouse gases. An earthquake or volcano could fundamentally alter our topology. More prosaically, Seattle could invest heavily in dikes, like New Orleans or the Netherlands. Regardless, the significant possibility of severe sea-level rise should be a consideration for the region’s long-term infrastructure investments.

* “Over 1 in 6 chance sea level rise + storm surge + tide will overtop” in 2080.

36 Replies to “Link and the Rising Seas”

  1. Seattle and Tacoma are relatively unaffected compared to Snohomish County.

    The Snohomish Valley becomes and inlet of the Puget Sound all the way to Snohomish and Everett (what’s left of it) is on a peninsula.

  2. “Interbay is a terrible place to create a new neighborhood, suggesting an eastern approach to Ballard is more responsible.”

    Your map doesn’t seem to really support this assertion. The parts of Interbay that have the most upside for TOD (North of Dravus) are a bit elevated too. Plus — we don’t necessarily have to create a neighborhood there for that route to be more effective and cost efficient than Alt D.

    Alt A is probably the best option overall — but it has a few bugs that drive its cost to high. They need to get rid of the Upper QA stop and go elevated along the East Magnolia walkshed and have an elevated crossing of the ship canal. Let’s leave Fremont for the Ballard/UW line.

    Going mostly elevated could also significantly move up the timeline. 2025 is not impossible with a 2016 vote if we avoid going with heavy duty TVM stations. The Upper QA just costs too much ($500M-ish?), and is too high risk — that station would probably need to be about 400 feet deep in order to make it under the ship canal at Fremont. That giant hole comes with a giant schedule impact as well.

    We can argue the details of which route is best on their merits, but I think this angle of the climate change as it relates to those decisions is pretty weak.

    1. If the UW line is going to eventually be built, that’s all the more reason to go UW to downtown via Fremont – 1/3 of the track to the UW will already be there.

      1. But not if it costs three times as much. We really have no idea how to judge each route right now because Sound Transit has basically said they don’t have much confidence in the numbers they have thrown out (in the initial assessment as well as the revised one). It is easy to assume that the revised set of routes is more accurate, but every official has said otherwise.

        A Queen Anne station is better than two Interbay stations, but not if it costs a billion more. There are other trade-offs as well. A route through Queen Anne would mean Fremont would have a more direct route to downtown and Belltown, instead of via UW or Ballard. A west side route would be more scenic (because it would be above ground). It is possible that the entire Ballard to UW route could be above ground, or cut and cover (saving money). If there are two routes to Ballard, that means that there could be two routes in Ballard (one heading east/west and one heading north/south) thus covering a wider swath of a fairly broad, very dense area (Ballard).

      2. > A Queen Anne station is better than two Interbay stations, but not if it costs a billion more.

        Why not? Queen Anne is a much more important destination than Interbay.

      3. Kyle S: The point is cost/benefit. If Upper Queen Anne is an important destination, which I agree that it is even if we disagree on how important – then what would make the most sense in terms of feeding people from that location to the system?

        You could build an ariel tram that connected upper QA to the lower QA station for a fraction of the cost of a subway stop there. Would it be as good as a subway stop? No. Would it make more sense considering the cost/benefit split? Yes.

    2. I agree.

      This is an interesting assessment, but I don’t see the city just letting this area flood. We are a bit inland, which means storm surges wouldn’t be as bad, either. Coastal lands that are isolated are of most risk because basically you are on your own in that regard (from slides as well). But the south end of Interbay (the area that would be underwater) is a major port, a major railway and a pretty big road (15th Ave NW). We are probably talking billions of dollars in activity there. The agencies involved won’t let it go under (water).

      Besides, a station close to the Garfield street bridge is crap. It really is the weakest station of the route through the west side. The only reason ST mentions it is because of spacing. It might make sense as a way to serve Magnolia, but all (and I do mean all) of Magnolia could be served quite well with one stop at Interbay, close to Dravus. That is one of the nicest things about Magnolia. Unlike any other place in the city, you can serve the entire region from one spot (its a big peninsula and all exits narrow to a small section of 15th). At best, a station around there would serve the handful of people who work at some of the offices nearby, and the summer tourists (some from the tour boat, and some who just want to walk from one end of Myrtle Edwards towards downtown). There is really very little potential for TOD at this end of Interbay.

      On the other hand, the other end of Interbay (by Dravus) already has some recent growth (in Interbay itself as well as on the Queen Anne side). I could see that part of town growing some more. If it does, then maybe (just maybe) you actually have a decent argument for the station at the other end of Interbay. If walk up riders overwhelm the station, then riders from the other parts of Magnolia could be shuttled to the station there.

      1. Ports are going to suffer a lot during sea level rise.

        While you can put a seawall around many things, you can’t put a seawall around a port. (Think about it.) As a result, sea level rise will require the relocation of *all* the port infrastructure. It will often be considered cheaper to relocate the port entirely than to elevate all the infrastructure.

      2. Exactly!
        We’ll have to choose to either rebuild or lose most salt water ports over time. This is not the case for Fishermans’ Terminal and Lakes Union and Washington due to the Locks. An LRT station at Dravus will spur development close to Fishermans’ terminal and push out industrial uses (see the Ballard side of Salmon Bay). Tempting as that may be for developers and the tax base, it would be throwing away a major advantage that Seattle has over other port cities.

      3. Intercontinental shipping is as old as ships. It’s not going away. It’s far, far too useful. Even if trans-Pacific shipping is sharply reduced, there are still gonna be ships moving stuff between ports on a pretty big scale.

    3. Asdf: Couple items on that (isolating Fremont vs Magnolia.)
      -Most of the people live in north Fremont so if there is only one station there, that isnt the spot for it.
      -If we capture east magnolia it will be IN ADDITION to capturing Fremont. If we go with Alt D, Magnolia/Interbay is permanantly out.
      -If we were to prioritze and build only one line, it would be Ballard to UW. Same ridership-ish as Ballard to Downtown but half-ish the distance.
      -I am taking cost, risk, and schedule into account. I don’t know why anyone would throw that out.

    4. Ross – agree about the Garfield bridge. Seems like it would be better to save the money then build a station there. Dravus/Interbay stop that is walking distance from East Magnolia (where there actually is some density) would be ideal.

      We’ll see what comes out of their second round of Ballard/downtown soon. A lot of this may not ultimately matter. As you point out, these are shaky cost estimates and this is all happening in a political vacuum.

      Once cost is considered with the knowledge of what might be possible with a ST3 package all of this could change. The question could become: are we going to get to W. Seattle or Upper QA?

  3. All the more reason to begin setting aside the engineering and dollar resources for a 4th Avenue on ramp to the Spokane Street Viaduct, even if that means adding a new deck to the north side.

  4. Our hardest problem in preparing for adjusting infrastructure is the number of unknowns involved, especially timeline, followed by the type and intensity of adverse conditions.

    The incidents and patterns listed in the article: are these things permanent or temporary, and over what space of time? A region-destroying earthquake is a virtual certainty. But before or after Earth falls into the sun or gets hit by a comet?

    Or: with a certain recent event in Snohomish County in mind…just what’s our choice besides frequent North-line transfers to buses? Should we beg Congress for more money? Or, and probably not as impossible, route the railroad through Ellensburg and handle Everett with hydrofoils?

    New York City recently had a little-remarked but really ominous event last hurricane, or the one before: subways suddenly flooded. There has probably always been a serious danger that any hurricane could do this with a lot more casualties. Has to do with how hurricanes work in that location, and the agreement is that they’re due to worsen.

    Quake, major storm- remember, our worst winds come from the south- or human errors in design or construction- Seattle Waterfront is a bad place for any of those things to happen. My own worst worry is major flooding through the south portal. Look at maps from 1900: that area had steamboats on top of it.

    Judging from all human history, best defense against uncertainty in an uncertain world is people, individually and in groups, in good physical condition, well-trained in basic skills like welding and stopping arterial bleeding, with a habit of automatic voluntary cooperation.

    “Survivalists” need to notice that none of the movies ever show Mad Max going to the bathroom, or finding anything to eat- old, old seriously dangerous human problems predating firearms, but effectively fought by cooperation. Even in Australia.

    And most of all, mental habit of considering changing natural conditions as perfectly normal, and adjusting outlook, daily life, education, and government accordingly. Fast response when a tunnel floods- but faster measures of prevention. Best done, at latest, before the project is out of the printer.

    Mark Dublin

      1. WOW.

        toggling back and forth between the 1895 and 1908 maps really shows how much growth there was here in just 13 years.

        its just almost unbelievable.

        there are also some details –like the Seattle/Everett Interurban– that kinda break your heart…..

  5. Is there a difference between letting people build homes in an area with a history of mudslides, and letting a transit agency build train tracks in an area with a history of being underwater?

    1. Sam, I think you’re asking a question that governmentally the closer people are to the responsibility for dealing with the matters you mention- the less they like the mention of it.

      The lagoon that used to have Jackson Street for its north shore is still there. Difference is more dirt in the water now. Hidden by the industry and stadiums on top of it.

      Usual take on such conditions is whatever’s out of sight is off the table. Generally to make room for the money that is. Of which so much is available before the flood or the landslide, that anybody who even knows about the problem thinks there’ll be enough to handle it afterwards.

      After they’ve retired from business, left office, or die. Meantime, a lot of revenue quickly surfaced in the days when waterways were the nation’s interstate highways. And the beach along the Sound was a perfect very long linear right of way from Everett to Seattle. Also near water and its very large interlocked economy.

      And remember how recent- and how permanently contentious, are fights over governing anybody’s land use. Natural the more tired any official gets of fighting, especially on the side of common sense, the more likely, and more eager they are to let nature handle it and take the blame.

      One long-needed and long-hated measure that would definitely help with the fight for common sense on every problem mentioned in this whole posting is the development of some strong, unified authority to marshal the effort and resources of this region. Starting with ending the damnable habit of every one of its agencies to fight like pre-1800’s Scots highlanders against all comers over every operational matter.

      Agreeing only that problems like collapses, derailments, ‘quakes and predictable flooding are some other agency’s fault. Fix that a lot of effort will be available for damage prevention, track repairs, and making service function while it’s expanding.


  6. The map does have one problem. It shows Lake Washington being affected by a 5′ sea level rise. Of course the ship canal will be affected only up to the locks.

    1. Looks to me like Lake Washington and Lake Union are shown exactly as they are today. The grey areas are parks. But at 9′ of rise in sea level the old Black River will start to flow again but backwards into Lake Washington. Boeing Renton will have to switch to making seaplanes. Seattle is in relatively good shape. Miami is screwed with just a 3′ rise in sea level. Maybe the better option for West Seattle is to just beef up the Water Taxi.

      1. I agree, Seattle doesn’t look that bad. One of the reasons is that we don’t have to worry as much about storm surges. But I also think that if it looked like this sort of thing was imminent, then we would build dykes. In this case, it looks like we could build one from the north end of West Seattle to Pier 91 and that would do the job. It is pretty easy to look at the map and see why that would pay for itself (there is a lot of business underwater in that picture). Hopefully the world will get its act together and it doesn’t come to that.

      2. (1) There’s a river (Duwamish River) draining into that area. You can’t just build a dike. You’d have to continuously pump the water out of the river.
        (2) A bunch of the business is ports. Can’t very well build a dike between them and the ocean.

        No, the Duwamish River valley would be allowed to return to being a river valley. New ports would be built to go with the new sea level. You could probably put up dikes a bit further inland next to the stadiums.

        But honestly, that’s not that bad for Seattle; the Duwamish River valley isn’t high-value construction. Just remember to build your new seawall next to downtown high enough, find a new train route to Vancouver BC, and you’ll be OK.

        Miami is, as noted previously, completely doomed.

      3. I think the only thing we have to worry about is high tide and storm surges. Average sea level won’t be that big of a deal (and doesn’t look that dramatic on the map).

        So, I was thinking more of a giant lock type system along with the diversion of the Duwamish. Close the dyke before really high tides, open it the rest of the time (most of the time). I’m guessing we get really high tides about a week out of the month, which means it would be closed about half the time during that week. This would obviously be really expensive, but I think it would be worth it if areas remain economically important. It may not matter if port traffic shifts to other places anyway (like Tacoma or Long Beach). There may be a lot of other, simpler, cheaper solutions as well (build a few dykes and raise a few ports, as you said). Protecting the area close to Pier 90 and 91, for example, looks really simple and fairly cheap (and would be worth it to protect the railway and roads in the area, even if there isn’t any light rail there.).

      4. Yes Bernie, it looks like I was wrong aout that. I suspect my browser screwed up the rendering of the map yesterday afternoon to lead me to my observation. Looking at it again this morning, it does look like it would take a 9′ rise to affect the ship canal and Lake Washington.

        As others have pointed out with reference to other areas, it would only be at times of high tide and storm surges that some areas are affected. I expect that the actual effect on the lake would be pretty minimal and could be mitigated by building up the dam a bit or with some flood control structure in the ship canal.

      5. while on a 2-D map a dike from W.Seattle to pier 91 conceptually looks good (and possible), it is important to remember that our underwater topography is muck like what our land forms are out of the water — steep.

        within 250m of those two end points you are already in 40m+ of water depth, and the majority of that 1.5 mile line is in 100m water or more (maxing out at about 165m). I don’t know that any dike anywhere has been built in depths like that.

        more reasonable, perhaps is to be thinking about breakwalls — basically partial “dikes” constructed in shallower water close to shore to diminish the power and effect of wave action (see Shilshole Marina, Elliot Bay Marina, et al). it seems that some of the worst effects come not simply with higher water flowing in and flooding, but that these higher waters bring the crashing, destructive effect of waves into/onto areas not engineered for this onslaught.

  7. I would think the first priority to worry about is the King County Sewage Treatment plant at West Point. It has somewhat of a seawall but it doesn’t really look high enough in elevation to survive a significant increase in the water level.

    1. Oh yeah. New York City had some serious problems with flooded sewage treatment plants in Hurricane Sandy. Sewage treatment plants are often built practically at sea level and the piping isn’t designed for the kind of backflow you’d get from being well below sea level.

  8. I live 560 ft above sea level, so once global warming kicks in, I’ll have easy beach access.

  9. Is that new Point Wells development being designed with rising water levels in mind?

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