By WIN GRUENING
By now, most Alaskans have heard of a jökulhlaup, a phenomenon where unstable lakes are formed from retreating glaciers that can result in a glacial outburst. The Mendenhall Glacier in Juneau has created such a lake, Suicide Basin. Hydrologists estimate it contained 14.5 billion gallons of water before it burst on Aug. 5 and flooded nearly 300 homes and hundreds of vehicles in the Mendenhall Valley.
The outpouring of support for flood victims has been heartening. Local volunteers and nonprofits, state agencies, and the National Guard have all pitched in to aid in clean-up and recovery.
But, as those efforts continue, the calls for action to prevent this from occurring again become more urgent. Hundreds of Juneau homeowners face a dilemma. Why rebuild if their homes will be flooded again next year? The economic consequences of delaying a community-wide solution are unthinkable.
According to the National Weather Service, the likelihood of a similar event next August remains high. Indeed, as serious as this year’s flood was, it happened when the Mendenhall River was relatively low. If the flood had been preceded by heavy rain, raising river water levels, the consequences could have been more disastrous, possibly with loss of life.
At their August 19 meeting, Borough Assembly members listened to gut-wrenching stories from Juneau residents whose homes were flooded. Also discussed were possible preventative actions.
An initial list of conceptual approaches to reduce or eliminate the impact of future floods came with the caveat that they would require further study and regulatory exemptions (possibly even Congressional action) were they to be accomplished on the most optimistic timeline.
Suggestions include:
- Suicide Basin: Relieve glacial pressure gradually by tunneling underneath Mt. Bullard allowing the basin to drain naturally into Mendenhall Lake. Another option is blasting rock into the basin to decrease the amount of water it holds.
- Mendenhall River: Increase the capacity of Mendenhall River by digging channels along the river and/or dredging the river to increase its depth.
- Mendenhall Lake: Use the lake as a reservoir to hold potential flood water. This would require dredging the lake, lowering the lake level with pumps, or building levees around the lake to hold more water until it can be safely released gradually.
Some options may be considered fanciful or unworkable. Certainly, the Suicide Basin alternatives should be eliminated because other basins could appear later as the glacier retreats even further.
However, there seems to be less skepticism about other possibilities among local contractors who believe that it is feasible to design a fix in a reasonable amount of time. One of them, Dave Hanna, testified that side channel excavations and levee constructions are common and effective ways of mitigating flood hazards throughout the United States. Furthermore, local expertise and capability for that work exists in Juneau.
Mendenhall Lake levees could be integrated into the trail system now being planned with the proposed large expansion of U.S. Forest Service facilities and improvements at the Mendenhall Glacier.
All these mitigation solutions will be expensive and would require a 35% local match if federal funding can be obtained. However, any federal assistance, including funding, is dependent on FEMA designating this flood as a federal disaster. FEMA officials visiting Juneau this week will evaluate and make that determination. It will require a high level of diplomacy and negotiation skills from city officials to convince them of the need for disaster funding.
Regardless of the plan ultimately chosen or any other possible funding sources, it may not be possible to construct a major project before Juneau faces another flood. Therefore, a two-pronged approach that includes short-term measures should be considered. For instance, raising riverbanks with rip-rap, installing temporary inflatable levees along the lake, and stockpiling sand for community use for sandbags all could be implemented before next August.
Regulatory permitting requirements notwithstanding, the Juneau community has the right to defend itself against any potential natural disaster and should invoke whatever emergency measures are necessary to protect its citizens.
A community task force must begin working on solutions immediately. It cannot rely solely on state or federal help. Local knowledge and expertise need to be included.
Time is critical. The clock is ticking.
After retiring as the senior vice president in charge of business banking for Key Bank in Alaska, Win Gruening became a regular opinion page columnist for the Juneau Empire. He was born and raised in Juneau and graduated from the U.S. Air Force Academy in 1970. He is involved in various local and statewide organizations.
There is lots of high ground on 36th in anchorage a child would move the capital to anchorage just to save money is all a child would do this now. IMAGINE
What, exactly, does moving the capital have to do with flood mitigation?
God wants you to take an oath to explain the linkage.
Maybe(?), if you’re going to permit home construction in a flood zone, it might be advantageous to build “elevated” structures on pilings?
I think stop build in a flood plain is the first start.
Hey now, stop using common sense.
Oh, yes, Win, climate change, eh? The question is how can we stick it to the other guys to cover our losses (at least allowing us time to bailout and leave)!
The area was never a flood plain in recorded history until just recently when the glacier created an unforeseen situation ( jökulhlaup). No one could foresee this disaster when building was occurring.
Most importantly, Home Insurers will certainly classify this area, as well as other areas throughout AK907 in similar circumstances, as Flood Zones! For those whom own residences will see sky-high premiums! And, for those who dispose of properties within said areas, the pool of interested buyers will most assuredly diminish!
I know Juneau is hard up for land, but building houses in a flood plain had risks. The houses built in the oxbow should never have been constructed. Any flood mitigation projects are going to reduce risk of another flood, not prevent it
Its unreasonable to call it a flood zone when there are 100yr-old+ trees standing between homes and the river (also in the oxbow areas). The recent flooding is what’s known in legal terms as an “unforeseen changed site condition.” The US government built thousands of flood control levees throughout our nation under the principal of mitigating unforeseen natural disasters. That principal applies here.
Did you say the land in the oxbow isn’t in a flood plain? Check a topographic map of the mendenhall area. Everywhere that is flat is in a flood plain.
The area is saturated. If you go ‘up the road,’ you’ll find the river banks contending with severe erosion. This erosion can quickly wipe out the buffer zones between buildings and water, as seen by last year’s flood. Then, there are the landslides, some not making the news. Each possible solutions could have consequences. Yes, a task force is needed.
You folks don’t seem to realize that these homes were never in a flood plain until the glacier receeded and created this problem. And no more homes are being built in this area as it is fully developed. It is a well established neighborhod that never expected to be in a flood zone. Please have some sympathy for these folks who are overwhelmed by this disaster.
Some builders are developing in potential problem zones in other parts of the Mendenhall Valley.
Time for an old fashion house raising party! There David you have some sympathy, you got the concrete stilts! Short of all that work , Lockheed – Martin has a Short blast laser that can be deployed at the basin to keep the ice levels down by remote operation all that is needed is POWER CORD layed up to it, even a constant monitoring system will do the task without a full time employee! This device is called in Military terms an LLD system see ‘https://www.lockheedmartin.com/en-us/news/features/2022/inside-the-lockheed-martin-laser-technology-that-defeated-a-surrogate-cruise-missile.html 300 KW class weapon! Please Juneau get smart!
… laid up to it. There, now its correct.
“Lay lady lay, lay across my big jokulhlaup , until the crest of summers flood let me see you smile.”
Why did you build downstream from a Glacier that’s been on the move? You didn’t learn a thing from the Auk clan did you? The indigenous folks witnessed this phenomenon over time and built their village far away from the Icy tines.
Now you seek Great White Father’s hand, maybe John Kerry can heal your land?
Appealing to the Feds for money is a sure sign that you’re addicted to Uncle Sam’s honey.
Ed, better yet, an annual application of BOMBS dropped at key areas on the glaciers surface which would create channels to alleviate this suicide pond JOKEOLAP nonsense.
Let’s get Senator Dan on this right away, that is if the Folks in the Ukraine will lend us some of our bombs.
Wayne, feel free to corectum my Kelsy Grammar above.
Bombs away!
A number of years ago the City of Homer agreed to a joint venture project with affected homeowners to build a seawall to protect against erosion on the Homer Bluff caused by a “Hundred Year” storm. The problem was, the waves that were causing the problem, turned out to not necessarily be a hundred year event and the Wall had multiple failures throughout the years resulting in lawsuits against the contractors, piling manufacturers, the City, and neighbor against neighbor. In short, you can’t beat Mother Nature! Juneau needs to know when to hold ’em, and know when to fold ’em.