- Welcome everyone to
Wednesday Nite @ the Lab.

I'm Tom Zinnen.

I work with the UW-Madison
Biotechnology Center.

I also work for the Division
of Extension Wisconsin 4-H.

And on behalf of those folks
and our other co-organizers,

PBS Wisconsin, the Wisconsin
Alumni Association,

and the UW-Madison
Science Alliance,

thanks again for coming
to Wednesday Nite @ the Lab.

We do this every Wednesday
night, 50 times a year.

Tonight, it's my pleasure to
introduce to you Adam Bechle.

He's an engineer with the
Wisconsin Sea Grant.

He was born in Green Bay,
Wisconsin,

and went to Green Bay
Preble High School.

Then, he came here to UW-Madison

to study civil and environmental
engineering as an undergrad

and stayed on to get
his master's and PhD,

also in civil and
environmental engineering here.

And then in 2016, he joined
the Wisconsin Sea Grant

as a post-doc, and then in 2019,

became a permanent member
of the staff there.

Tonight, he's gonna talk with us

about adapting to a
changing Great Lakes coast.

Would you please join me
in welcoming Adam Bechle

to Wednesday Nite @ the Lab?

- Thank you, Tom,
for that introduction,

and thank you Wednesday Nite
@ the Lab for inviting me

to speak about this
important issue

facing our Great Lakes coasts.

Fluctuations in Great Lakes
water levels

are very challenging for our
coastal communities

and coastal residents,

particularly when
we see extremes,

Extremes like extreme
low water levels

that were seen in record lows
in 2013 on Lake Michigan

and extreme highs that have
been seen on Lake Michigan

and Lake Superior
in 2019 and 2020.

But before I get into talking

about adapting to those
changing coastlines,

I'd like to give a little
bit of a background

on Wisconsin Sea Grant

and why Wisconsin has something
called the Sea Grant program.

So Sea Grant is a federal
university partnership

between the National Oceanic
and Atmospheric Administration

and university partners
around the nation.

In total, there's 34
Sea Grant programs

on all of our oceanic states
and Great Lake states,

as well as Puerto Rico and Guam.

Wisconsin's Sea Grant
is based at UW-Madison,

with satellite offices
at the UW campuses

in Superior, Green Bay,
Manitowoc, and Milwaukee.

Wisconsin Sea Grant focuses
on research, education,

and outreach for the sustainable
use of Great Lakes coasts.

And so we fund basic research

on a number of
Great Lakes issues,

and as well have
outreach specialists

and communication
specialists like myself

who talk about issues like
Great Lakes water levels,

coastal engineering,
fisheries, aquaculture,

water quality, social science,
tourism,

and a number of other issues
in the Great Lakes.

So why do we have a Sea Grant
program in Wisconsin?

Well, one thing I like
to point to

is the length of the
coast that we have

in the United States.

The Great Lakes has
4,530 miles of coastline

along the United States.

That's more than
the Atlantic coast

and the Gulf coast combined.

Not quite as much
as the Pacific coast

when you factor in
Alaska and Hawaii,

but still quite a substantial
amount of coastline

in the Great Lakes.

Wisconsin itself has over
800 miles of shoreline

between Lake Michigan
and Lake Superior,

and the Great Lakes
are extremely important

to the state of Wisconsin.

It's where we live.

Some of Wisconsin
lives near coastline.

There are $6 billion
of improved property

within a quarter mile of the
Great Lakes coasts.

Great Lakes are also a great
economic driver for the state.

The Great Lakes ports
in Wisconsin

generate over $1.5 billion
of revenue annually.

And the Great Lakes are
a place that we recreate.

There's over 200 coastal beaches

along Wisconsin's
Great Lakes shoreline,

and those coastal beaches
are not only important

for our recreation,

but they also drive tourism
to those communities

that depend on them.

And so we have a really
valuable resource in Wisconsin

in our Great Lakes coasts.

How did we get them?

Well, the coasts and the
Great Lakes in general

are intertwined with
our glacial history.

Over 2 million years ago,

the Laurentian Ice Sheet
descended

into the Great Lakes region
from the north

and over time, advanced and
retreated numerous times.

And as it did that,

it started to carve out
the Great Lakes Basins.

The Great Lakes Basins
mostly were old river beds

with softer sediments,

and really carved out the
basins that we see today.

The last glacial
advance in Wisconsin,

in the Great Lakes in general,

was the Wisconsin glaciation
about 25,000 years ago.

Then the glaciers started
to retreat for good

out of the Great Lakes,

and we were left with the
landforms we see today.

Now, when the Great
Lakes retreated,

we didn't see exactly the
configuration of Great Lakes

that we have today.

The drainage patterns and
water levels of the Great Lakes

changed over that following
thousands of years.

As water changed course
throughout the Great Lakes,

the land surface in the
Great Lakes area rebounded

from having the heavy weight
of the glaciers on top of it.

The northern part of the Great
Lakes are rebounding faster

than the southern part, so
we're having a tilting effect

because the northern parts
were under thicker ice

and for longer periods of time.

And so all those changes,
the tilting land surface,

the water flowing out
through channels and rivers,

have changed the drainage
outlets over time

until about 4,000 years ago,

when we ended up
with approximately

our current configuration
of the Great Lakes.

So what were we left with?

Well, we have five Great Lakes.

We have Lake Superior,
Lake Michigan,

Lake Huron, Lake Erie,
and Lake Ontario.

And the Great Lakes
are all connected

through a series of
connecting channels

flowing all the way
from Lake Superior

out to the Atlantic Ocean.

So Lake Superior sits about
600 feet above sea level,

flows out the St. Marys River,

and through a series of dams
and power plants up there

through the St. Marys River
out into Lake Huron.

Now, Lake Huron is
connected to Lake Michigan

through the Straits of Mackinac,
and this connection is so wide

that the water levels of
Lake Michigan and Lake Huron

are pretty much the same.

In fact, we call it
Lake Michigan-Huron,

and we treat it
as one large lake

when we're talking
about water levels.

Out of Lake Michigan-Huron,

the water flows through the
St. Clair River

into a small lake called
Lake St. Clair near Detroit

and out the Detroit River
into Lake Erie.

Now, there's no dam or human
control structure on that flow,

but that river is
dredged periodically

to allow navigation,

and so that does
change how much flow

does go through that river

when that dredging
operation does occur.

And then Lake Erie outlets
over the Niagara Falls,

drops over 300 feet
into Lake Ontario,

of course, through a river,

and then Lake Ontario sits
about 243 feet above sea level.

Lake Ontario outlets through
the St. Lawrence River

through a series of dams and
out to the Atlantic Ocean.

And so this is a large,
interconnected system of water

and those water levels
in the lakes

change over periods
of years and seasons

and months and even days.

And so our period of record
of water levels

in the Great Lakes extends back

from about 1918 to
the present day.

And in that water level record,
we see highs, lows,

periods where water levels are
above the long-term average,

periods where water levels are
below the long-term average.

And these variations are
on the order of feet.

Recently, in the late 2010s,
all the five Great Lakes

have been above their
long-term average,

and each Great Lake has broken
some form of water level record.

Water levels, in their
extremes, especially,

can really change our coastline.

When we have low water levels,

things like navigation
shipping are stressed

because water depths can be
insufficient to pass large ships

or even recreational craft,
and things like water intakes

for our drinking water
treatment plants

sometimes can be stressed

not having enough water depth
to function properly.

At high water levels,
especially at the extremes,

we have a higher probability
for flooding along our coasts,

as well as erosion
of our coasts.

So today, I want to
talk a little bit

about what is going on with
Great Lakes water levels,

what drives them up
and drives them down,

how is that changing the coast,

and then what are some
strategies that are being used

to adapt to this change?

So first, what is a water level

or a lake level
in the Great Lakes?

When you hear about it
in the news,

or hear about it in maybe
a scientific publication,

really we're talking
about an average

over a daily, monthly,
or annual period.

And typically, monthly average
is what's used

to describe the lake levels.

That's because we can
see water level changes

on a scale of time scales.

We see inter-annual variations
where water level goes up

and down over a period of years.

We also see seasonal changes
in water levels,

where we have, typically
on an average year,

our highest water levels
in the summer

and our lowest water levels
in the winter.

We also have changes out there
on the lakes all the time.

Wind waves, which if
you went to go look

at the lake right now,

you'd see that rippling
and maybe white-capping.

That changes on the
order of seconds.

And then when we have
large coastal storms,

big winds blowing in, we get
storm surges, seiches,

those change water levels on
the order of minutes to hours,

and sometimes even up to days.

But in general, when we
talk about lake levels,

we're talking about that
monthly average.

That can kind of remove some of
those short-term fluctuations

and really help us focus on
how much water is in the lake.

So let's take a little bit
more detailed look

at the water levels
in Lake Michigan-Huron.

So again, we have
a period of record

of just over a hundred years.

Lake Michigan-Huron has
experienced a record high

in October of 1986,
a record low in January of 2013,

and the range between those two
is about 6.4 feet.

Now, within the
water level record,

we see a seasonal fluctuation.

Again, kind of peaking
out in the summer

and being lowest in the winter.

And on average,
that's about one foot.

Some years may be more,
some years may be less,

but the average variation
seasonally is one foot.

As I said before,
we have periods of high

and periods of low.

We've seen rapid changes
in water levels

on Lake Michigan-Huron.

In the '50s, we had a
rise of over three feet

in just a year and a half,

and then in the '80s, we
saw a drop of over four feet

in just over two
and a half years.

So we can experience pretty
quick changes in water levels.

We can also see
prolonged periods

of high and low water levels,

like the 1970s, where
we had eight years

of prolonged high water levels

or the early 2000s,
where we had 15 years

of prolonged low water levels.

It's a bit similar story when
we look at Lake Superior.

Lake Superior has a
slightly smaller range

between its record high, which
was set in October of 1985,

and its record low,
which was from 1926.

That range is about 3.9 feet,

but we also experience
rapid changes,

rapid increases,
rapid decreases,

periods of high and
prolonged periods of low.

So this is something we
definitely need to expect

when we live on the
Great Lakes coast,

is that high water levels
and low water levels,

based on history, will
always be coming back.

So what drives the Great Lakes
water levels up and down?

Well, it's helpful to think
of the Great Lakes

kind of as a budget,

thinking of water going
in and out of the budget.

And one of the big
drivers is rainfall,

precipitation falling
directly on the lakes.

That is quite a substantial
amount of water.

We also have rainfall that
falls on the surrounding lands

and runoff into the lakes.

The lakes are also very big
surfaces of water,

and so we get quite
a bit of evaporation

directly off the
surface of the lake

and back into the atmosphere.

Those three terms,
precipitation, runoff,

and evaporation, when lumped
together and added up,

are called the net basin supply,

the supply of water into
and out of the lakes.

So precipitation and
runoff add water,

evaporation takes it away.

So if precipitation and
runoff exceed evaporation,

then the Great Lakes
in general will rise.

If precipitation and runoff
are lower than evaporation,

we have more water leaving
the basin than entering,

then generally the
water levels will lower.

Now, there's other components
to the water budget.

We have, as I mentioned,
connecting channels

connecting the Great Lakes.

So in the instance of
Lake Michigan-Huron,

flow comes in from the
St. Marys River

out of Lake Superior,

and out through St. Clair River
out on its way to Lake Erie.

We also, in some cases,
have man-made diversions

into and out of the lake system.

So Lake Michigan-Huron has
the Chicago River diversion.

So around 1900,
the Chicago River,

which once flowed
into Lake Michigan,

was reversed with the Chicago
Sanitary and Ship Canal

to flow out of Lake
Michigan-Huron.

That is a diversion of water,

diversion from the
natural pattern.

So it's interesting
to kind of consider

how much water is
actually being diverted

through that specific diversion.

So the Supreme Court
decreed in the 1960s

the flow of the Chicago River
flowing out,

and that is 3,200 cubic feet
of water per second.

Now, if we take that
over the course of a year,

that adds up to 750 billion
gallons of water.

Which sounds like a lot,
and it is a lot of water,

but when average that amount
of water over the surface area

of Lake Michigan-Huron,
which is 45,000 square miles,

that amounts to just
under an inch of water

out of Lake Michigan-Huron

going out through
the Chicago River.

Definitely not negligible,
but certainly small

compared to what
Mother Nature can do

to water levels
on the Great Lakes.

There are other diversions
into Lake Superior

on a similar order of magnitude,

and humans also
have some control

in some of the
connecting channels

where we do have locks and dams
where flow is regulated,

but in general, Mother Nature
is really what drives

these many-feet rise and fall
in water levels.

Humans do have some control,

but that's more on the order
of inches.

So speaking of Mother Nature

putting water into our
Great Lakes,

precipitation, as I mentioned,

is one of the big components
to the water budget.

We have precipitation records
dating back just before 1900

all the way to present day.

Over this long period of time,

the wettest five years
in history

occurred from 2015 to 2020.

In fact, we set
our all-time record

for water precipitation in the
Great Lakes Basin in 2017,

and then almost broke
that record in 2019,

so the two wettest years in
history in that five-year span.

That's a big reason why,
as I mentioned,

we've had record-high
water levels

throughout the Great Lakes
in 2019 and 2020.

So taking a more detailed look
at this road

to record-high water levels,

let's drill down
in Lake Michigan-Huron

and kind of see how that
lake went from January 2013,

new record-low water level,

all the way up to new
monthly high records in 2020.

So in the years preceding
that record-low water level,

there was quite high
evaporation on the Great Lakes,

which drove water levels
down and kept them low.

Then in 2013, we hit
that all-time record low

on Lake Michigan,

followed up with a
spring and summer

that had very high precipitation

and therefore high runoff
as well

that raised the water levels,

but they were still below
our long-term average,

shown in red here.

Then we had a low
evaporation winter.

We didn't get much seasonal
decline in water levels

that we normally
see in the winter,

and that seasonal decline
is usually driven

by increased evaporation
in the winter

and low precipitation
in the winter.

Well, we didn't have a whole
lot of evaporation that winter,

so we didn't see much
seasonal decline.

Followed up with a wet spring
and wet summer

that drove water levels
just about average,

and then that again was followed
by a winter of low evaporation,

bringing water levels from those
record lows in 2013

up to around average.

Things were a little calm
for a few years, and then

we had that record-setting
precipitation year

in 2017 that drove water levels
well above average.

Followed it up in 2019

with a near-record level
of precipitation,

and then we stack those
up with another winter

of low evaporation that
really set the table for 2020

to break records on
Lake Michigan-Huron,

and we set new
monthly record highs

from January all the way
to August in 2020.

July of 2020 was
just two inches off

the all-time record-high water
level in Lake Michigan-Huron.

So really, an unprecedented rise

from record-low
water levels in 2013,

almost setting our new record
all-time high in July of 2020.

Since, we've sort
of topped out there.

2021, at the time
we're recording this,

we've had a slight drought
in the area,

and that's had
low precipitation,

not a whole lot of water
entering the lakes.

Gotten some relief from those
record-high water levels.

Sitting here, September of 2021,
we're still well above average,

but definitely not in
that record territory.

So where can you go to find out

about Great Lakes
water levels today?

The Army Corps of Engineers
every month

puts out a monthly bulletin
of Great Lakes water levels.

A web search for that term,

Monthly Bulletin of
Great Lakes Water Levels

will bring it up, and
with it is a graphic

showing a two-year history
of where we've been

with water levels, as well
as a six-month forecast

of where water levels
are predicted to go.

So to orient you of
this monthly bulletin,

I've got here a Lake
Michigan-Huron bulletin

from September 2021.

So across the top, we see time,
we see years going back to 2019

and months going back two years.

On the vertical axis, we have
the lake level elevation,

and on the left-hand side
is feet.

The dashed blue line there

is the long-term
average water levels,

and you can see that
seasonal cycle in there,

peaking out in the summer and
bottoming out in the winter.

The red line here
is where we've been.

This is the recorded water
levels over the last two years.

And then those little lines
across the top

with years on them, those
are the monthly record highs,

and then on the bottom
are monthly record lows.

And so you really
get a full picture

of where water levels have been

and how that compares
to our record levels.

So we can see here,
2020, as I mentioned,

set new monthly record highs
from January to August in 2020.

And since then, we've kind
of been steadily declining,

as I mentioned,
been in a drought.

The supply of water
coming into the lakes

has been a little bit lower,

bringing us to where we are
right now, again,

as we're recording
in September of 2021,

kind of halfway between
the long-term average

and the monthly record high.

The forecast for the
next six month

is shown in the
dashed green line,

and around it is kind
of a cone of uncertainty

of where those water
levels might go.

It's kind of like a
hurricane forecast.

The further out you get,
the less certain we are

of where water levels will be,
but looking forward,

we're likely gonna be sticking
in that above-average range,

at least for the next six
months on Lake Michigan-Huron.

We can also look Lake Superior,

this monthly water level
bulletin.

We can see where
Lake Superior was,

setting monthly records
in 2019 and 2020.

And actually as we sit now,

Lake Superior is right about its
long-term average water level,

and the six-month forecast
has the lake

sitting right in that
area of long-term average.

Certainly this can change if
we get a wetter fall or winter

than expected or lower
evaporation than expected,

but this is the current forecast
as far as it's provided.

So you can go and do a
web search for that any time

and find the latest
water level bulletin

as well as the water level
forecast.

So what's gonna happen
with water levels

under a changing climate?

Well, one thing we do know,

we know that we expect a
warmer climate going forward,

as well as a wetter climate
going forward.

So what does that mean

to the Great Lakes
water level budget?

Well, that suggests an
increase in precipitation

and an increase in runoff
to the lakes,

but that warmer weather
will likely lead

to an increase in evaporation
from the Great Lakes.

So an increase in water
coming in

and an increase in water
going out.

So prior to about 2013,

the general consensus running
through climate models

and routing them through
models of water levels

in the Great Lakes was that
evaporation was gonna win

and that lake levels are
going to trend lower.

However, it was discovered that
the treatment of how runoff

from the land was making
its way into the lakes

in those models was
under-predicting

how much runoff was happening.

And so more recent studies,

including one from Michael
Notaro and collaborators

at the UW-Madison have shown

that we don't have a
clear trend anymore

of where we expect
water levels to go

under a changing climate.

Really, it depends on how much
warming we anticipate

or will actually get,

and how much increase
in precipitation we get,

because those two signs
are kind of fighting

with each other.

So depending on which
climate model you use,

they see slight decreases
in water levels,

slight increases in water level.

So not a clear conclusion
anymore,

like we had prior where
we thought water levels

were gonna go lower.

But one thing we do
want to stress

is that historical variability
is likely to remain.

We're still likely
to see extreme highs,

still likely to see
extreme lows,

possibly higher highs and lower
lows than we've seen before.

With more extreme precipitation,
more extreme evaporation,

we could be in for greater
periods of those extremes

than we've seen before.

So looking forward, it's
really best to anticipate

those extremes to continue.

So I've covered a bit
about what is going on

with Great Lakes water levels,

and now I wanna
talk a bit about,

so how are the coasts
changing in response?

As I mentioned before,

when we have extreme
low water levels,

that really puts stress on
our navigation facilities.

In some cases,
particularly when we had

those record-low water levels
in the early 2010s,

there were marinas that
had to dredge continually,

boats were having a hard time
getting in and out

of the facilities,

ships could not contain a
full load and were losing money

based on having to
not be fully loaded

just so that they had enough
water depth to travel.

Lots of dredging was going
on in those low water levels,

and of course, concerns
about drinking water intakes,

whether there was
enough water depth

for those to
function as designed.

With high water levels,
the concerns become more

with flooding and erosion
and infrastructure damage

from our high water levels.

And so I wanna focus a bit
on coastal flooding first,

and then I'll talk a
little more about erosion.

So coastal flooding
doesn't happen

just with high water levels.

It's a combination of high
water levels and coastal storms.

So when a coastal storm blows in

with strong winds blowing
towards the shore,

those strong winds can
push up a storm surge,

so piling up water against
the lake, the shoreline.

That moves in water
on the Great Lakes

that can be anywhere from a foot
to several feet of storm surge.

On top of that are waves.

Those waves, when they
hit the shoreline,

waves typically will break when
they get to shallower water

and will run up the slope
and cause additional water

to get close to inundating,
say a home,

especially in low-lying areas.

Now, at average water levels,
a given storm

may not cause flooding,
may not bring the water

up to a level of a home,

but when we have
high water levels,

that storm has a head start
at causing flooding.

And so the same storm
under average water levels

may not cause flooding, may
cause quite a bit of inundation

and flooding for a home and
for a wide stretch of homes.

One place where this
happens in Wisconsin

is along the bay of Green Bay.

The bay of Green Bay
is long and shallow,

oriented to the northeast,

so that when strong
northeast winds come,

quite large storm surges can
pile up at the end of the bay

and cause problematic flooding
for the city of Green Bay,

as well as some of the
cities along the bay,

particularly the western arm
of Green Bay.

Places like Suamico, Oconto,

they've all been
dealing with flooding

during this record-high
water level period.

I want to talk about two events
in Green Bay in particular

that were notable in this
high water period,

December 1st of 2019
and April 28th of 2020.

Those were some notable
flooding events,

but to put those in context,
let's actually go back in time.

April 8th, 1973,

the worst coastal flood
recorded in Green Bay history.

The headline from
the Press-Gazette was

"Floods Force 800
From Their Homes."

Large storm, northeast winds
blew down the bay,

brought in cold April icy water
into those homes

and flooded out a large area
of low-lying land near the bay.

So what was going on here with
storm surge and water levels?

Well, those northeast winds
kicked up

about a 3.3-foot storm surge.

Pretty big.

Water levels were above average,
no record highs,

but they were quite
above average.

That brought the water level
in Green Bay

up to about just over
584 feet above sea level,

and so that caused that
widespread flooding.

So that 584-foot mark
I've marked here on the graph

and is an important number
to keep in mind

when we're comparing
to this event.

Shortly after this
devastating flood,

the city of Green Bay
constructed a dyke

along its Green Bay coastline
in hopes to not experience

that sort of devastating
flooding again.

And it's functioned quite well,

and there hasn't been
that bad of flooding

from a coastal flood since,

but let's look at what
has happened since then.

Well, let's take us to
December 3rd of 1990,

and this storm surge
was the big one.

The strong northeast winds
coming down the bay

kicked up a 5.4-foot
storm surge.

Compared to the
next-highest storm surge

in the historical record,
which was four feet,

this is a foot and a half higher

than anything that's been
recorded in modern history.

This was the big one.

When the Army Corps of Engineers

analyzed coastal flooding
in Green Bay,

they estimated this was
about a 1-in-300-year storm,

or to put it in other terms,
in an average year,

there'd be a 1-in-300 chance

of a storm surge like this
occurring on Green Bay.

The biggest one that we've
seen in the historic record.

Fortunately, Lake Michigan

was at roughly average
water levels here,

depicted on the graph
by the red line.

So when you add those
average water levels

with this extreme storm surge,

that brought the water level
in the bay of Green Bay

roughly to about 584 feet,

similar territory
to that 1973 flood.

With the dyke in place,

there wasn't that devastating,
widespread flooding,

but if water levels
had been above average,

things could have been worse.

When we look at the timing of
water levels and storm surge

specifically in Green Bay,

looking at the top
five storm surges

that have occurred in
our modern history,

the only one that
really occurred

at elevated water levels
was that 1973 event.

Otherwise, they've
occurred at near-average

or below-average water levels,

which brings us to
our current period

where we've had
record-high water levels.

So December 1st, 2019,
strong northeast winds

coming down the bay created
a 2.4-foot storm surge

on the bay of Green Bay
and caused local flooding

right along the bay there.

In terms of how large
this storm surge was,

this was about an
average large storm

that you would see
in a given year.

Obviously some years,
there'll be bigger storms,

some years may not
see a storm this big,

but roughly, this is about
what you'd call a big storm

that you'd see in a year.

Then in April of 2020,
another storm surge,

a little bit larger, about
2.6 feet, came down the bay.

Again, strong northeast winds
caused localized flooding

around the bay area and a
little bit into the city.

Green Bay Metro Boat Launch
was swamped.

This storm was a
little bit bigger.

This is roughly a storm you'd
see every two or three years.

So not a remarkable storm.

Certainly a big one, but nothing
compared to that 1990 storm.

But when you add it on top
of record-high water levels,

brought the bay up to just
about that 584-foot mark,

causing localized flooding.

Again, that dyke's in place,
so the widespread flooding

that was seen in 1973
didn't happen,

but it just underscores
how much coastal flooding

is impacted by our Great
Lakes water levels.

So when we're at
record-high water levels,

it doesn't take a remarkable
storm to cause issues,

but when at average
water levels,

it took the largest storm surge
ever recorded in Green Bay

to get to that same level
compared to high water levels.

So really, flooding
is problematic,

especially when we
have high water levels,

something we've seen
in the last few years.

Green Bay is definitely a spot

where coastal flooding
is concerning.

It's low-lying, and
it's like I said,

the bay is long and shallow,

which is really conducive
to large storm surges.

Most of Wisconsin
Great Lakes shoreline

is not that low-lying.

In fact, a lot of it is
up on coastal bluffs,

10 feet high, 100 feet high,
130 feet high,

and not really subject to
flooding from the coast,

but there are other issues
that come with a coastal bluff,

and that is erosion
and bluff failure.

So what happens there?

Well, much like with flooding,

coastal storms
come into the mix,

creating storm surge and waves.

And when those storm surge
and waves reach up high enough

that the waves can touch
the bottom of the bluff

and start to impact it,

those waves bring a
lot of power and force

and start to wear away
sediments there.

And so again, at
average water levels,

it's harder for those storms
to reach the base of a bluff.

But when we have
higher water levels,

it's that much easier for the
same coastal storm

to bring waves up and impact
the base of the bluff.

If the water level gets
up and over the beach,

we don't have that
benefit of the beach

being able to have waves
break over it nicely.

Those waves can come in
and strike the bluff

at an even higher height
in that case.

And so sediment is
continuing to be worn away

at the base of the bluff.

It can steepen that toe up

up to a point where the soils
that comprise that bluff

can no longer stand
at a stable angle.

Each soil has sort
of a natural angle

that it will remain stable at
and not be at risk of collapse,

and as you steepen up further
and further from that angle,

you increase the likelihood

that there will be
a slope collapse.

And so as waves continue
to remove material away

and steepen that toe,

that risk becomes
greater and greater.

Now, depending on the type of
soil that a bluff is made of,

it may fail in a number
of different ways.

Some places experience
a deep-seated slumping,

where the whole slope will kind
of slide out into the lake.

That's not the most common form
of slope failure in Wisconsin,

but it does happen
in a number of places.

More common is called sliding
or translational sliding.

That's where we see a series
of smaller failures

on that unstable, over-steepened
part of this slope.

So we'll see a smaller
section of the slope

kinda collapse and fall off
down to the base of the bluff,

and that leaves a steeper
portion up the bluff.

That steeper portion further
up the bluff is now unstable

and subject to
potentially collapsing.

This can be worsened if
the high water levels

and waves continue.

They remove the material
that had just eroded

down at the bottom of the bluff,

and then start to continue
to work on that bluff

and steepen up the slope.

Eventually, the upper part
of the bluff slope

will collapse and slide,

and this failure works its way
up the slope of the bluff.

Even if there was
no more wave erosion

once we've
destabilized the bluff,

that slope is gonna want to get

to a more stable configuration,
a more shallow angle.

And how does it do that?

Bluff failures and collapses.

So that is how we eventually
see recession of the coastline

at the top and where our
bluffs start to encroach

upon things that we value
like homes, businesses, parks,

and things like that.

A recent study out
of the UW Geosciences

and Wisconsin Geological
and Natural History Survey

by Russell Krueger, Luke Zoet,
and Elmo Rawling

looked at bluff evolution in
response to high water levels

using some real
advanced methods,

drone surveys, and
slope stability modeling

to really understand
how fast these failures

work their way up a bluff.

And they found that unstable
services progress up the bluff

at a rate of about
4.4 meters per year,

or roughly 15 feet per year.

So kind of to put
that in context,

a low bluff, maybe
10 or 15 feet high,

can really experience
failure in recession

at the top of the bluff
almost immediately.

Our higher bluffs in the state,
over a hundred feet,

now, we're talking on the order
of a decade

before erosion that occurs
at the toe of the bluff

works its way all the way
to the top of the bluff.

And we can kind of
see that visually

if we look at a couple
different sites in Wisconsin.

So first looking
at a shorter bluff

from the Kenosha area in Somers.

This is about 30
to 40 feet tall.

1970s to 2012, there wasn't a
lot of change in this bluff.

2012, as you'll recall,

we were almost at
record-low water levels.

So not a whole lot of erosion
happening at the toe.

Well, from 2012 to 2017,

we had quite a rise in water
levels on Lake Michigan,

a lot of wave erosion
reaching the toe,

and that recession happened

at the top of the bluff
pretty readily.

Just in that five-year window,
went from having some distance

between the edge of the bluff
and the house

to by 2017, the back porch
of that house

falling in the lake.

One more year down
the road in 2018,

the foundation is
exposed of that house

and unfortunately
had to be removed,

demolished by crane
for safety reasons.

But this house was lost
to erosion in Wisconsin.

A big impact of erosion here.

If we look at a taller bluff,
this is from Milwaukee County.

We see in 2012, reasonably
stable configuration.

Lake levels are
close to record lows.

By 2017, lake levels have risen,

waves have impacted
the toe of this bluff,

and we see some erosion and
failures working their way up,

maybe a third of the way
up the bluff.

Much taller bluff here, using
maybe some of those trees

as a reference point as
we move forward in time.

By 2018, we lose some
of those evergreens

on the bluff slope.

2019, still, the failure's
working its way up.

And then by 2020,

we don't see much vegetation
on the bluff slope anymore.

Those failures have
worked their way

to the top of the bluff,

but it took a lot longer
than our low bluff example,

so really demonstrating
that failure process.

So lower bluffs, typically
we'll see those impacts quicker,

definitely at the top
where we have homes

and things we care about.

The taller bluffs, we'll
see them eventually,

but it may go a little unnoticed

because it can be
kinda hard to see

what's going on
down at the lake,

but we know that failure is
working its way up the bluff.

So definitely something
to be aware of,

no matter what the
coastal configuration.

Water levels and waves
are a big impact

on Great Lakes
coastal bluff erosion,

but they're not the only thing

that affects Great
Lakes coastal bluffs.

One thing we need to think about

is water coming from the
land surface.

So as water flows down

from the top of the
bluff to the base,

that can erode soil particles

directly off the
surface of the bluff.

Groundwater in the bluff slope.

When it comes out in the
middle of the bluff,

it's coming out at a
high enough rate,

it can cause sapping or erosion
of the soil particles there.

Also, groundwater in a
slope reduces its stability.

It's not as strong,
and that stable angle

will have to be
shallower or less steep.

And so high groundwater
conditions can also factor in

to bluff failure
and bluff erosion issues.

And so we really
need to think about

all these natural processes
at a bluff site.

Certainly lake levels and
wave erosion a main driver,

but we can't ignore
other factors.

Now, as humans, we live on the
coast and we make changes,

and some of those aren't
exactly the best thing

for bluff stability.

One thing we do is we build.

We add surfaces where water
can no longer be absorbed.

It runs off, and
possibly causing

increased surface
water erosion problems.

So we have to be
mindful of where

those impervious surfaces go.

Vegetation on the bluff
naturally occurs on a bluff.

The roots of that vegetation,
beneficial for a few reasons.

One, the roots hold the soil,
at least to some depth,

let the roots go and add
strength to the soil.

They also absorb
water from the soil

and put it up into
the atmosphere,

and so they help remove
excess water from the bluff.

So if we come along and
we remove that vegetation,

we're decreasing that
stability of the bluff.

And then another thing we do
is when we see toe erosion

at the base of the bluff,
oftentimes we try to stop it

to save the properties
at the top.

This can be done by adding
erosion-resistant materials

like concrete, oftentimes
armor stone, rock,

to sort of keep that wave energy

from being able to
erode the bluff slope.

However, this kind of
fundamentally changes

how those waves
interact with the bluff,

and instead of
eroding sediment away

and sort of being
absorbed maybe on a beach,

they're striking a hard surface.

And changing that
near-shore dynamics

can, in some cases,
have negative impacts

at neighboring properties,

sometimes increasing erosion
around the structure.

And so it's something
to be aware of

and definitely something that
does happen in some cases.

You can look at these
changes yourself

on a great tool that
we have in Wisconsin

called the Wisconsin
Shoreline Inventory

and Oblique Photo Viewer.

You can either search
that name online,

or you can type in the web
address, no.floods.org/wcmp.

This is something
that was put together

by the Association of
State Floodplain Managers,

the Wisconsin Coastal
Management Program,

and Dave Mickelson,

who is a professor emeritus
at UW Geosciences,

compiling historic aerial photos
of the coast

and putting them in a viewer
for everyone to take a look at.

So up there are
photos from the 1970s,

the 2007, 2008, 2012 photos

that were acquired by the
Army Corps of Engineers,

and then since 2017,

the Coastal Management
Program has been working

with the Wisconsin wing
of the Civil Air Patrol

to routinely acquire
photographs of the coast.

And these are extremely valuable

in being able to track
changes on the coast,

see how certain bluffs
and structures

have responded over time,

and really get a good picture
of how things have changed.

There's also data layers
up there

looking at assessing
bluff stability.

In some cases, we have erosion
measurements up there as well,

but really a great resource
to help understand

how specific areas
have been responding

to changing water levels.

Again, that's the Wisconsin
Shoreline Inventory

and Oblique Photo Viewer,
no.floods.org/wcmp.

A great resource to check out

when we're trying to
explore the coast.

So I covered how the
coasts are changing

with specific emphasis
on how water levels

are behind some of that change.

Now, I want to talk a little bit

about what strategies
are being used

to help adapt to these changes.

So when I talk to
folks in my job,

talking to property owners,
to municipalities,

people who are
dealing with erosion,

I'd like to start with a
top-down approach

to protecting
coastal investments.

And part of that is
the top is where,

typically, what
we care about is.

That's where homes are,
businesses are, infrastructure.

And so starting up at the top

and trying to see
what is the problem,

how close is erosion or
flooding to causing an issue,

and work our way down
towards the lake,

because, as I'll talk
about in a moment,

fighting with Lake Michigan
and Lake Superior

is tough and it's
very expensive,

so if we can work our way
from the top down

and see if we need to do that,

that's usually the
best course of action.

So what can we do at
the top of the bluff?

Well, managing our land use,
managing where water flows,

and managing vegetation are all
great things that we can do.

In terms of managing land use
before something's built

in siting things intelligently,

not having them too close
to the edge of the bluff

and trying to keep them
out of nature's way.

As we've covered,
erosion and flooding,

these are natural processes
on the Great Lakes.

It's what the lakes want to do,

but it's problematic when we put
things we care about in the way.

And so if we can stay

as far out of nature's
way as possible,

that can usually be the
most effective solution.

So in terms of doing this
in a policy perspective,

some of our counties and
municipalities in Wisconsin

have enacted building
setback ordinances

that try to keep new
development out of harm's way.

These will often include
things like erosion rates

over a certain amount of time
for a life of a building.

They range anywhere from
30 years to 100 years,

depending on how
conservative you are.

And then slope setback,
if a slope is going to fail

to its natural
stable slope angle,

accounting for having that
distance in that setback.

And then oftentimes they
include somewhat of a buffer

to provide a little
bit of breathing room

in case erosion happens

at faster rates than
they have in history.

And so these can be
really effective ways

at keeping new development
safer from the threat of erosion

and keeping them
out of harm's way

so we don't have to try
and fight these problems

with Lake Michigan.

For existing buildings,

obviously they can't
be sited initially

further away from the coast,
but relocating a building

can be a pretty
effective strategy

at getting out of harm's way.

Requires you to have somewhere
to move the building,

but as this example shows
from Sheboygan County,

a home was pretty close
to the edge of the bluff

and a bluff failure
precipitated the homeowner

to really consider
their options.

And since they had
a large enough lot,

they were able to hire
a house mover to pick up

and move the house back
sufficient distance away

from that erosion threat,
reconnect the utilities,

put in a new septic system.

All of that totaled up,
of course,

but it was probably cheaper
than trying to stop the erosion

and keep the house where it was.

Again, building relocation

is not maybe necessarily
always an option,

but it's something to
keep in the toolbox

when we're trying to
adapt to changing coasts,

staying out of nature's way.

Other things we can do
at the top of the bluff,

managing healthy vegetation.

As I mentioned, certainly
not clear-cutting

the vegetation we have there,

but encouraging deep-rooted
native vegetation

for the benefits of holding
the soil and removing water.

Keeping a no-mow buffer
near the edge of the bluff

will help those
roots grow deeper

and help slow down any water

that wants to flow over
the edge of the bluff.

Views of the lake are high value

when we're at properties
that are close to the coast.

So obviously, if we're
covered with vegetation,

some of those views
may be impeded on,

but really a good way
to get those views back

is to frame views and have
low-growing vegetation

over those sight lines.

If there's trees in the way,
rather than cutting them down,

exploring if they
can be pruned up

to give you those
viewing corridors,

trying to maintain as much
healthy vegetation as possible

and balancing that with the
use of the site.

Management of water at
the top is also important.

Knowing where
drainage is flowing,

making sure gutters
aren't pointed

directly over the edge of
the bluff, things like that.

Rain barrels are a popular
choice to really hold that water

and avoiding putting things
like rain gardens

or tilled beds right near
the edge of the bluff

where water can go
right into the bluff.

As we work our way
down the slope,

a lot of those principles
still remain good practices.

Managing water, making sure
it's slowed down

so it's not picking up speed
as it goes down the bluff

and eroding the bluff surface.

One good way to do that and
slow that down is to, again,

ensure there's good,
healthy vegetation

on the bluff surface
as possible.

Sometimes the bluff is
too steep to be stable.

That steepness may be
threatening a property.

If a house can't be moved,

reshaping an unstable slope
is sometimes needed.

Oftentimes this is done
by cutting back

the slope of the bluff
to a shallower angle,

back to that stable angle of
whatever the bluff material is.

If space is an issue, retaining
walls in building terraces

can also be an effective option

to increase that
slope stability.

In some cases, adding fill
to get that stable slope

is possible, but that can
oftentimes be expensive

and hard to get permitted

because then that fill would
encroach upon the lake.

So things that
would be considered

if bluff stability is
really threatening a home.

Then as we work our way
down to the shoreline

and these other options
aren't a solution,

the home is still at threat,
it can't be relocated,

then we start thinking about
trying to slow toe erosion

if that's absolutely necessary.

And so the concept
here is putting

erosion-resistant material
or reducing the wave energy

reaching the toe to kind
of stop that process

of erosion at the toe.

There are a number of ways this
is done in the Great Lakes.

By far the most common is
what's called a rock revetment.

This is a sloping face
of erosion-resistant,

most often rock, stone,

that will resist
movement by waves

and those are large rocks.

And on the Great Lakes,

especially on the open coast
of the Great Lakes,

we're talking about ton rocks,
multi-ton rocks,

to be able to resist
the force of waves.

And under those large rocks
are smaller stone,

so that when water gets
in between the gaps

in those large rocks,

it doesn't undermine the
structure from underneath.

Again, revetments, most
common type of structure

to reduce toe erosion.

Other ones that are used
sometimes are a seawall,

which is a vertical structure,

either made out of
steel or concrete,

functions somewhat
similar to a revetment,

but when waves hit them,

they reflect a lot
more wave energy

and can cause some more
issues in the near shore.

But again, the concept
there is to directly resist

erosion from the lake.

Breakwaters are sometimes used

to reduce wave energy
at the coast.

They're built out into the
water and waves hit them,

either blocking the wave energy

or reducing the wave energy
that the coast sees

to reduce the erosive capacity.

And then an emerging area
in the Great Lakes

is something called
nature-based shorelines.

This is trying to work
with nature or mimic nature

to provide some
protection of the coast.

Oftentimes it's a hybrid
with some harder structures

with rock or concrete, but in
the example that I show here,

this is what's known
as a marsh sill.

There's a little
bit of rock sill,

kind of like a small
breakwater out in the water.

The waves hit those and
that reduces wave energy

a little bit.

We've got marsh
vegetation growing.

As the waves hit those, reduces
a little bit of wave energy.

And then it's backstopped
by some smaller rocks

for whatever wave energy
reaches the shoreline

to stop erosion there.

Nature-based shorelines have
been much more developed

on our nation's ocean coasts

and internationally
on ocean coasts.

The Great Lakes, we're
still developing here.

We've got ice, we've
got freshwater species

that don't work the same
as our ocean coasts,

so it's definitely an area

that's growing
in the Great Lakes

and something to keep an eye on,

whether or not this sort of
solution is suitable at a site.

It has more habitat benefits

to aquatic and
terrestrial habitats

than conventional
armoring of the shoreline

with just rock.

So it's definitely
gaining a lot of interest.

Where can you learn more
about these sorts of options?

Well, Wisconsin Sea Grant,

we've just published
two new guides,

one, "A Property Owner's Guide
To Protecting Your Bluff,"

going into more detail
about a lot of the concepts

I talked about, going from
working your way from the top

down to the bottom,
good practices to use,

managing land use,
vegetation, water,

and then slope stability,

and, if needed,
shore protection.

And then we've also put
together a guide called

"Nature-Based Shoreline Options
For Great Lakes Coasts."

As I mentioned,

this is a developing area
in the Great Lakes,

and so we've put together
some basic techniques

that are being used
now in the Great Lakes,

as well as some case studies

of where they've been
implemented in the Great Lakes

to help folks wrap
their head around

what nature-based shorelines are

and kind of how they can
be used in the Great Lakes.

We also have two guides called
"Adapting to a Changing Coast."

These are a little
higher-level views.

One is written for Great Lakes
coastal property owners,

covering some of the
options they can use

to address flooding and erosion,

and one is more geared
towards local officials

thinking about policy,
funding options

that might be helpful for
adapting to a changing coast.

All those can be found on the
Wisconsin Sea Grant website,

seagrant.wisc.edu,

or a web search for
Wisconsin Sea Grant.

It has lots of information
about these issues,

as well as the whole
profile that Sea Grant has:

fisheries, aquaculture,
water quality, tourism.

Lot of great information
out there,

both from Wisconsin Sea Grant,

as well as from
many of our partners

at the state and
federal and local level.

One thing I'd like to
point out on the website

that might be particularly
useful to some of the viewers,

a website called "Resources
for Property Owners."

This is where we've collected
a number of useful resources

for Great Lakes
coastal property owners

to help understand what's
going on on the Great Lakes.

Waves, erosion,
sediment transport,

how to assess vulnerability
to some of these hazards,

how to pick options
going forward.

And then when it comes time,

if you need to work with
an engineer, a contractor,

some resources to help
understand that process

and a list of known contractors
and engineers to start from

when trying to do
that sort of work.

Again, seagrant.wisc.edu,

can find a lot of great
information about water levels

and more there.

As I close out, I'd
really like to acknowledge

that I don't do this work alone

and Sea Grant doesn't
do their work alone.

We have strong partnerships
at the state and federal,

university, regional,
and local level.

Just to name a few,
we work closely

with the Wisconsin Coastal
Management Program,

Wisconsin Department of
Natural Resources, NOAA,

the Army Corps of Engineers,

UW-Madison researchers,
UW-Milwaukee researchers,

researchers at universities
across the state.

The Southeast Wisconsin
Regional Planning Commission,

Bay-Lake Regional
Planning Commission,

Association of State
Floodplain Managers,

and a lot of local partners
as well.

And so really we'd like
to acknowledge

and thank them for their work
with us on these issues.

I'd also like to acknowledge
a lot of this information

that was shared
today was developed

under a NOAA Regional
Coastal Resilience grant

that was funded by NOAA

through the Office of
Coastal Management,

helped make a lot
of this information

and the guides
I mentioned possible.

With that, I'd like to leave
you with just a reminder

that the Great Lakes are
really important to Wisconsin,

both economically, as a sense
of place, a place we recreate,

and they face challenges,
particularly when we have

extreme water levels,
high and low.

And from history,
we kind of anticipate

we'll continue to face these
challenges in the future.

They may be made worse
by climate change,

but working to adapt to them

is in the best interest
of everyone in Wisconsin,

because of how important that
that resource is to our state.

With that, I'd like to again
thank Wednesday Nite @ the Lab

for having me, and thank you
for your attention

and have a great day.