- Okay, my name is Reesa Evans.

I will be moderating most of the

ecology stream for
the next couple days.

I'm going to
introduce Buzz Sorge,

who I don't have a
written introduction for,

but I've known him
a long time, so...

Buzz is the lake manager for

the West Central Region,
which is where I am,

and he has been an
innumerable resource for me

through the years as I've
learned lake science.

So when I have a question,
I go to Buzz,

and when he retires,
I'll be in big trouble.

Thanks, Buzz, go ahead.

- Well, good morning, everybody.

Thanks for coming
in this morning.

How many people understand
what the term limnology means?

Well, limnology is the study
of fresh water ecosystems,

and it incorporates
an understanding

of the biological, physical,
and chemical factors

that influence our rivers
and lakes and streams.

So what we're going to be
talking about this morning

is the basics of lake health.

What makes a lake a lake ?

So when we start
thinking about this,

we have to think about
Wisconsin as a state.

Well, how did we get all this
fresh water in our state?

Well, it's really a product
of the periods of glaciation

that came through the state

and we really have
what we estimate as

somewhat over
15,000 natural lakes

and tens of thousands of miles
of rivers and streams.

And so as the glaciers
came through this country,

they gouged out
portions of the earth

and created these basins then
in our natural lake ecosystems

that filled with water
and created those lakes

we love to recreate on.

So when we think about
the history of these lakes

across the state,
you know our lakes

are 10,000+ years old,

so what has been
our impact on them?

We really started
impacting our lakes

in Wisconsin about
150 years ago,

just before the cutover,
when we took the pine off

the northern parts of the state

and the woods off,
and as Europeans colonized.

So some of our earliest lake
users and development on lakes

goes back to the mid-1800s,

and that's when the
forests were clear cut.

But then really,
most of the development

started on Wisconsin's lakes
post-World War II,

when we had those
resources in our economy

to enjoy those
systems out there.

So I'll talk more about that

later with that
type of development,

and then redevelopment
really came significantly

as a lot of those
cabins were upgraded

to the second homes and
first homes in the 1990s.

How do we value our lakes?

And lakes do provide
services to us as a society,

they provide ecosystem
services, I mean,

we love to be near our lakes.

We are a creature that just
loves to be near water,

and so the cultural and societal
values we have for lakes,

but these ecosystems
services, the wildlife,

the clean water they provide,

are very valuable to us,
especially in the Upper Midwest

and Minnesota and Wisconsin.

But our lakes are
changing faster than ever.

Some of these are indexed by
more frequent algal blooms.

How we've developed
our shoreland areas

has really impacted
in lake habitat,

and aquatic invasive species.

These are the three main
stressors that we see

on Wisconsin's lakes today
that we are working on.

If we think about
this, I don't know

how many folks have had a
chance to look at this report,

but it's Wisconsin's
Changing Climate report,

it was published in 2011, and
really gave us some insight,

so what we can expect to see,

especially how it impacts
our water resources.

Some of these major
drivers of climate change

on our water resources are
simply thermal impacts.

We're a bit warmer.

That means ice on
for a shorter period of time.

It comes on later,
goes off earlier in the
spring.

Definitely, I think
folks who live in,

especially north central
and northwestern Wisconsin,

the drought we went through
6, 7 years ago.

We're kinda out of that,
but it really

impacted lake levels up there.

We had many lakes that really

had significant impacts
on their lake levels,

and then in many other
areas of the state

we've seen increased
storm densities.

In western Wisconsin
when I worked,

2014 and 2013 especially

we had some incredibly
intense early summer storms

that leave 5 inches, 6 inches
of rain in a few hours.

And we had multiple storms like
that come through our area.

Some of these key
water resource impacts

associated with these changes:

in those wetter areas
we definitely see
increased flooding.

And in our reservoir ecosystems,

this is a big problem for them.

Increased frequency of
harmful algal blooms

in some of these systems,
with those increased flooding

comes increased pollutant load
to those systems.

And then,
these warmer summer temps.

I think if you think back,
especially to 2014.

In August we were
seeing surface temps

in our lakes pushing 90 degrees,

that's very abnormal
for Wisconsin lakes.

Conflicting water use concerns,

when we get into some
of these drier areas,

especially in more of
our agricultural areas,

we have that competition
for that ground water

especially to grow
our commodities,

and then we're seeing
impacts on lake levels

and stream flows
associated with that.

Changes in water levels,
I talked a bit about that,

especially in the north when
we're in the drought period.

Increased sediment
and nutrient loading,

this is very much associated.

We put more water on the land,

we got the ability to
transport more

pollutant loading to
our lake resources.

And increased spread of
aquatic invasive species.

As we're changing
these water temps,

we're changing the
characteristics of these lakes

that can support new species.

And it's very common
for somebody to be fishing

either on the Mississippi
River, the Great Lakes,

or on another state,
and then the next day,

be on a northern Wisconsin
or southern Wisconsin lake.

So we have the vector
transport because of

how mobile we are
in society today.

This is just some
examples of some

of those things I was
just chatting about.

Be it a very high
level of nuisance,

blue-green algal growth, or
increased sediment loading.

That's a shot on Lake
Mendota with a stream

coming in carrying a
very high sediment load.

So as we kinda flip
the switch a bit,

what makes a lake a lake?

So we really have
to understand these

physical, biological,
and chemical properties.

But when they're
in proper balance,

that's when we are at that state

of high quality lake health.

And so, often our
goal is to either

sustain a lake in high
quality lake health

or restore its lake health.

So let's talk a bit about the
physical properties of lakes.

We really have to start with
physical property of water.

Water is
a pretty unique substance.

It is a universal solvent,

so lots of stuff will
dissolve into water,

but its physical properties
are most unique because

water actually weighs the most
at 4° Centigrade.

And that's like many other
chemical constituents,

when you heat them
up they get lighter.

Well, not so much with water.

So as you cool water
down, it gets lighter,

and that's a very good thing,

especially in Wisconsin
and the Upper Midwest,

cause that's what make
ice float, simply.

So and we don't have a
lot of this fresh water

on the earth's surface either,

less than 1% of the water on
the planet is fresh water,

and then about 1/1000 th
of that is actually

in our earth's
freshwater lakes.

So these are very, very
unique water resources

that we have in Wisconsin.

So thinking a bit
about water then,

you have to
understand a bit about

how does that water
get to the lake

and why does that
lake have water in it?

So we think about
the hydrologic cycle.

So in Wisconsin, we get about
30+ inches of rain a year.

As that falls to the earth,
some of that

is intercepted by vegetation
and evaporates right back up.

Some of it falls on
our lakes and streams

and evaporates back up,

and some of it that
seeps into the earth,

is taken up by the plants,

and then evapotranspired back
by plant growth.

But when we think about
these lake basins out there,

as the glaciers did gouge these
holes in the earth's surface

they simply filled
with groundwater.

So when you see a lake,
what you're really looking at

is the interception of that
lake surface representing

the ground water
table in that area.

So as far as lake
types in Wisconsin,

we really can classify them
often by their water source,

and so we have seepage lakes,
groundwater drainage lakes,

drainage lakes, impoundments,
and then oxbow lakes.

A seepage lake is
where an ice block

was gouged into the
earth's surface,

created this depression
in the earth's surface,

and then as the
glaciers receded,

it simply filled
with groundwater.

And the major source of
water to our seepage lakes

is groundwater, we have no
streams coming in or out,

generally have
groundwater coming in

one side of the lake
and going out the other.

And so some of these lakes
are some of our lakes

that are most susceptible
to water level fluctuations

during periods of
drought, because if
we aren't getting that

rainfall on the earth's surface,

then those groundwater
levels go down

and that's characterized
in our lake levels.

The other thing that
happens on these systems too

when we're in
drought-ier periods,

the evaporation actually
from the lake's surface

exceeds the amount of rainfall.

So if we're in a 20 inch,
20-some inch rainfall year, and

our normal is like 34 inches,
32 inches, something like
that,

in a warm summer we
might have an evaporation

that exceeds 30 inches
on that lake's surface.

So the water budget
becomes out of balance

and then our lake
levels go down.

This is just a shot of
a piece of landscape

up in Chippewa County,
where I work,

where the glacier left
many of these small ponds

and lakes across the landscape.

The lake in the central
portion of the photo

there is Round Lake.

Has no inlet or out, Round Lake,

and really it's just
groundwater coming in

largely from the north,
the top of the photo

and out the side,

and it just represents that
groundwater level in the area.

Groundwater drainage lakes,

these are lakes that are
placed high up in the landscape

but there's enough water coming
to them from the groundwater

that they've created an outlet.

And so they definitely are
dominated by groundwater

coming through the
system, but they also

have a stream leaving them.

A good example of
that is Sand Lake,

up on the Rusk/
Chippewa County border.

This lake gathers
the groundwater

from the groundwater
shed around it

and then flows out to the
Chippewa River to the north.

Drainage lakes, now we're
changing things up a bit.

These types of lakes, where
they're more dominated,

their water source,
by surface water,

and groundwater's
less influential

on the characteristics
of the lake.

So we got a stream coming
in, stream going out,

and because of that we
have a larger catchment,

a larger watershed that's
bringing water to the lake,

and I'll talk more about that.

And as you think about this,

a seepage lake often has
a very small catchment,

and they tend to be our
higher quality lakes.

Those are most of our
clear water lake systems

across Wisconsin.

And we get into
our drainage lakes.

These are a bit more productive,

and often water quality
is a little bit less

than what we see in
our seepage lakes.

This lake is Long Lake
up in Chippewa County.

It's a pretty unique
lake ecosystem,

and I'll talk more about
it's physical nature,

but it drains a stream in from
the bottom of the photograph,

up into the shore of the lake,

and then it goes out
through another lake chain

over to the Chippewa River also.

It'd be a surface flow.

Alright, impoundments are what
we have lots of in Wisconsin,

or reservoirs,
they are referred to.

And they're not really lakes--
they're dammed up rivers.

These are often some
of our more significant

management challenges,
because we're really

taking an ecosystem
function of the river,

which is to transport
material out of a watershed,

and we're stopping that function

and creating the
surface water body.

This is Lake Altoona
on the east side

of Eau Claire, Wisconsin,

and it's a lake that I've
been engaged with management

over the last 30 years
of my career.

The Eau Claire River
is a very high sand port,

sand transport system.

When we first started
looking at this lake

back in the early '80s,
the delta had moved

about a third of the way
down the lake.

The lake had filled
about a third full with sand.

Its sedimentation rate

was tens of thousands of yards
of sand every year.

We estimated that as high
as 70,000 yards of sand a year

were being deposited
in this system.

It's a huge
management challenge.

It comes down to, how much
does society value this lake?

Is this lake going
to be sustained

as part of the greater
Eau Claire community?

And the people that
lived around the lake

have a lake management district,

and in concert with
Eau Claire County

have found the resources.

This has just finished
another dredging project

literally a couple of weeks ago,

and it was like the third
time it's been dredged,

so they're dredging
almost once a decade

and they took
almost 200,000 yards

of sand out of this system.

And that is just to
sustain it as a lake basin.

Another interesting
lake we have in our area

north of Eau Claire,
this is Lake Hallie

in the village of Hallie.

This lake is an Oxbow Lake,

it was part of the
Chippewa River one time,

and at the time of the cutover,
when a lot of the water,

the timber was coming out
of the Chippewa River basin,

this lake was used
for log storage.

And so they put a
dam on this system

and it's what we refer
to as a raised lake.

So this lake only
has a mean depth of

about 9 feet
in average depth.

But the uniqueness about this
lake, up until the mid-1990s

it had very, very, high levels
of groundwater flow into it.

So it's a very
shallow ecosystem,

we would think
it'd be very warm,

but it had such high
groundwater inputs,

we could sustain trout
in this lake year round,

because on the far
end of the lake

near the bottom
of the photograph,

we had very high spring
flow into this system

and it would keep the
water cool enough where

it would sustain a stocked
trout fishery for the community.

And the other thing that
that high groundwater flow

did in to this system, was
it's warm water in the winter.

Groundwater's about 50 degrees

as it comes in to
lake ecosystems,

and it kept the upper 20 acres
of this lake open

all through the winter,
no matter how cold it got.

Well, as we've developed
its groundwater shed,

here on the left side
of the photograph,

a couple of things have gone on.

We've put some high
capacity wells in

to provide water supply
for the community.

But we've put a lot of
impervious surface down,

and that impervious surface
now is running water off

that used to infiltrate
into the ground.

And we lost our
groundwater flow.

And the consequences
of that have been

we are no longer able to, say,
net trout,

to keep this lake as a put and
take trout fishery in the summer

so the lake has lost
that ecosystem service

to the community.

Because we have less
groundwater coming in

we don't keep the lake
open anymore in the winter.

And in the mid-'90s, when
some fishermen were out there,

we got some calls in the office

and said, "The fish are
dying in Lake Hallie."

And, sure enough, now this lake,

we have to sustain the fishery
in the lake

through a winter aeration system

because we don't have that
open water area out there.

And I'll talk more about why
that occurs in lakes like this.

So as we think now more about,

that's the lake types we have,

we have these physical
characteristics
that impacts lakes,

and we'll talk about
mixing and stratification,

why lake depth's important,

how long water
stays in a system,

retention time or flushing rate,

and watershed or drainage
basin area to lake area ratio,

where this lake is
positioned in the landscape,

and influences of
watershed runoff.

So when we think about
mixing and stratification,

most lakes in Wisconsin,
we call them dimictic.

That's simply a term
that means our lakes mix,

top to bottom, twice a year.

So if we think why
does this happen,

as I was talking about earlier,

water is most dense
at four degrees,

so in the spring
where the ice is off,

what we see when we're--let's
start with winter.

As we're coming out of winter,

and we have zero degree water
virtually on the surface.

So that's the lightest water
in the lake at that time,

that's why that ice is floating.

And then as that ice melts,

that lake water warms
to about four degrees,

and once it's the same
temperature top to bottom,

or what we call isothermal,

that lake easily is mixed.

So if we put wind energy
with our spring wind events

onto a lake's surface, then we
get the spring mixing event.

And we call that
spring turnover.

And that really
rejuvenates the lake,

so then our water
chemistry in this system

is the same top to bottom.

It's just like kinda putting
a blender into the lake,

it mixes top to bottom.

So as we come out
of spring here,

as we approach that time period
in a month or so from now,

that summer condition
begins to set up.

As that surface water warms,
as that lake temperature warms,

that water now
becomes lighter water,

and it sets up a stratification
is what we call it.

The lake actually layers
into three distinct layers

as we go into the summer.

So that top layer
over there on summer

is called a epilimnion,

and it's a fancy term for
the top layer of the lake,

and that layer is
really dependent

somewhat on the depth of lake,

but how warm or
cool the summer is.

So in most lakes in the summer,

that top layer is anywhere from,

it could be as little as
six feet, or two meters,

on some lakes that
are very protected

that do not get much
wind energy on them,

to up to ten meters or
approximately 30 feet.

And then below that is
the transitional layer,

we call that the thermocline,

and any people who
love to swim or dive,

when you swim down into the lake

you'll feel that great
temperature change,

and that happens
very, very quickly.

Then our coolest water,
our most dense water,

stays on the bottom of the lake.

So then as we move into fall,

as that top layer then
begins to cool again,

once it reaches four
degrees centigrade

or 39 degrees Fahrenheit, it
becomes the most dense water

in the lake so what's it do?

It simply sinks.

And then causes this
fall mixing period

that will continue on
until ice up.

And then again we rejuvenate
that whole lake ecosystem.

So let's go into, you know,
why does lake depth matter?

Deep lakes, definitely
we'd use this term,

they layer up, they stratify,

and shallow lakes stay
continuously mixed

so there's a couple of
things going on here

that really can influence
lake characteristics,

especially in the summer
and in the winter.

In our deep lakes,
what's going on,

and in our shallow lakes,

you think of our lakes again,

they're 10,000 years old, right?

So we've been growing plants
and algae in these systems

for 10,000 years,
and we've accumulated

all this really rich,
organic sediment

on the bottom of these lakes.

Well what happens when you put

organic matter and oxygen
together, you grow bacteria.

Same thing happens in your
compost pile in your yard,

you're decomposing that, well,

that same process is
virtually occurring

on the bottom of every
lake in the state

and it goes on 24/7, 365.

Well, now does that
bottom portion of the lake

maintained as habitat or not?

Well it may or may not,

it depends upon the volume of it

and the rate at
which those bacteria

are consuming that oxygen out
of the bottom of the lake.

So in our state we only
have a handful of lakes

where the oxygen concentration
remains high enough

to sustain a fishery
in that portion

of the lake as a trout fishery.

So that's why we have
Trout Lake, Green Lake,

are a couple of the
more common lakes,

that still have
lake trout in them.

But we also need that
oxygen down there

for many of our
cool water species,

especially our walleye
fisheries because

there's a fish species named
cisco that lives down there

and they need that cool water
place for the cisco to live.

That is a very
important resource

for sustaining many of
our walleye fisheries.

It doesn't need it in all
lakes, but some lakes.

So if we've changed the
characteristics of the lake,

where we've increased the rate

of that organic
material being produced

by putting more nutrients
into that system,

we increase the rate at
what oxygen depletes.

If we don't have enough oxygen

stored in that
portion of the lake

because of this high rate
of sediment decomposition,

that area goes without
oxygen, we call that anoxia,

and then fish species
and other aquatic life

can't really live down there.

Some invertebrate species can,

that can sustain really
low oxygen levels,

but the things we
might relate to

can't live in that
portion of the lake.

So conversely, in
a shallow lake,

that same process is going on.

And as long as that lake
stays continually mixed

we're fine, but the
whole chemistry changes

when we go without
oxygen in the bottom

of the lakes down
there and lakes start

to release nutrients back
into the water column.

Well, that's not a problem
up in our deep lake,

where those nutrients
stay down there

on the bottom of the
lake and aren't available

for algal production
through the growing season,

but in some of
our shallow lakes,

which one I'm gonna
show you shortly,

that can be extremely
problematic,

cause we call that
internal loading,

or the ability of the
lake to self-fertilize

itself from its lake sediments.

And in some of those
lake ecosystems,

we have approximately
200 of these lakes,

we call them polymictic, or
they mix many times per summer,

and every time they mix
after a period of anoxia

or when that sediment
water interface

has gone without oxygen
for several days,

you get a pulse of
nutrients buildup there,

boom, the lake mixes, where
does that nutrients go,

it goes up in the water
column, it becomes available.

The other issue
with shallow lakes,

especially lakes,
let's say, shallower

than maybe 12, 13
feet and shallower,

when that ice layer goes
on in the winter time

that creates a barrier now

between the atmosphere
and the lake.

Well, as long as sunlight is
getting through that ice layer

the lake still sustains
a relatively high amount

of dissolved oxygen to
sustain a fishery in there.

But when we put the
snow on that ice,

we turn the lights out,
when we turn the lights out,

we turn off the
algal production,

the ability of that lake
to produce its own oxygen.

Then that fishery becomes
at the mercy

of the amount of oxygen
that's stored in that water.

And so, if you hear the
term "winter-kill lakes,"

well, what's really gone on
in that system is the lake,

simply because of the bacterial
decomposition in the sediments,

has used up all the oxygen
in the lake, and the fish die.

So lake depth definitely
does matter and impact.

This is a lake that I've
worked on for many years now.

Now, folks, if you
have your own lakes,

and you want to get like an
average depth of your lake,

this is Cedar Lake, it's up in
Polk and St. Croix Counties.

This is a polymictic lake.

Well, if you look at
that darker gray center

where the words Cedar Lake are,

that's the only
portion of the lake

that's about 25
feet or different.

The wind fetch on this
lake is north to south,

it's almost two miles long,

and what happens
with Cedar Lake is

that 25 foot from really
about 18 feet and shallower,

when we go to quiescent periods,

not much wind during the summer,

Cedar Lake will set
up and stratify,

but has very enriched
bottom sediments.

Those bottom sediments
are releasing phosphorus

into that lake water and then
when we get a thunder storm

or a large wind event
that comes through,

the lake will mix top to bottom

and we'll end up
with an algal bloom.

But one of the things
I wanted to show you

here with this slide was,

you can simply calculate
your mean depth

of your lake very easily,

and it's simply the volume
of water in the lake,

which in this lake it's
about 20,000 plus acre feet,

divided by the number of acres,

and that gives us
your mean depth of 18.

So you can do this
in cubic meters,

and square meters on top,

but this information is
usually available to you

on any of your lake maps.

Retention time
and flushing rate,

this is very important.

Algae need times to get off
many generations to live,

and pollutant flushing is
also dependent on this.

So when we use the
term retention time,

that is simply, if you
drained your lake down,

how long would it
take it to refill?

The inverse of that
is flushing rate,

and that would
give you, in time,

how many times per year
your lake would flush.

So when we think about
a lake like Long Lake,

that is relatively high
up in the landscape,

it's a deep lake,
it's a large lake,

without a lot of
water coming into it.

If we drained Long
Lake out totally

it would take seven years
for that lake to fill up.

So water stays in that
lake at least seven,

but when we think about a mass

of pollutants coming
in to a system,

it takes about three of
these flushing times,

or the lake has to fill,
empty, fill, empty,

three times before we
move the pollutant on.

So it can have an
impact for a long time,

so if we get a big storm event,

would bring a lot
of pollutant loading

or phosphorus into Long Lake,

it would be potentially

impacting water quality
for a couple of decades.

That's opposed to Lake Altoona
which I showed you earlier,

where they have a large river
coming into that system,

it's a relatively shallow basin.

The average time water stays
in Lake Altoona is 22 days,

but when we get into
a high flow event,

it may be only in
there less than a day,

a few hours, during
a flood event.

So we can take a lot
of pollutant loading

and flush it through
a system like that.

The other impact on lakes
when we think about that is

how much land physically
drains to each acre of lake.

When we have lakes that have
less than ten acres of land,

ten acres of watershed
to each acre of lake,

those tend to be our higher
water quality systems.

There just isn't enough
land mass out there

to produce enough inputs
of sediments and nutrients

to impact water
chemistry that much.

And that's opposed to some
of our lake ecosystems,

and I'll talk about
that, or reservoirs,

where we may often have
two, three thousand acres

of land draining to
every surface acre

in a reservoir ecosystem.

So landscape
position, simply think

about the land of
Wisconsin on a tilt,

or your watershed
a bit on a tilt.

Those lakes high up in the
system near the top of the hill,

so to speak, those
are our seepage lakes.

The ones highest up,
often don't even have

a lot of groundwater
in flow to them

so drought can produce
extreme effects on them.

We have lakes up in the
Chippewa County forest

and the Chippewa marine
that their lake levels

still have never
recovered totally

since the '88, '89 drought.

So we're that many decades out.

And as you move down
through the system,

you're accumulating
more water all the time

and you have higher
groundwater inputs

and surface water input.

So those ones higher up, smaller
watersheds,

less runoff, tend to
be where you find your

higher quality lake ecosystems.

The Sand Lake I showed
you, the Long Lake,

both very, very high
quality systems.

They're very high
on the landscape.

Lake Altoona,
very low on the landscape.

It's right near almost where

the Elk River dumps
into the Chippewa.

Large land mass
that drains to it,

has a much poorer water quality
and sedimentation issues.

So let's switch over now
a little bit to think about,

so that's kind of the
physical nature of this lake

and how their function, it's
mass of water coming in,

mass of water in the basin,
those types of things.

But what are the
characteristics of that water?

How is it influenced?

That ultimately will influence

the biological
characteristics of the lake.

So if we had just distilled
water in our lakes,

we wouldn't have any
life in our lakes, right?

So we all need a mix of
nutrients in our life.

We have micronutrients, which
are made of the elements

on the side of
the lower graphic.

Some lakes are harder, softer.

That's simply the
amount of dissolved ions

in the lake ecosystem.

And dissolved
oxygen is obviously

incredibly important
in our lakes.

I talked a bit
about winter-kill.

To maintain a viable
warm water fishery,

our dissolved oxygen
concentration needs to be

5 or above
to sustain all life stages

of that fishery and that system,

that is our water
quality standard

for a warm water fishery.

What I really wanna focus
on are nutrients a bit,

especially the
ones we can manage.

So when we really think about
the primary nutrients in

lake ecosystems, there's carbon,
nitrogen, and phosphorus.

It's that ratio especially

of how they relate
to one another.

But when we think
about the nutrients

we may have some
ability to impact.

We really can't impact carbon,

we really can't impact nitrogen,

that much of the
atmosphere is full of it.

But we can impact this
element called phosphorus.

So phosphorus really
is a major driving

in ecosystem health in most
of our lakes in Wisconsin.

We need phosphorus
in these systems.

It's a critical component
in all forms of life.

It's part of our DNA, our RNA,

our energy metabolism
for us to sustain ourselves

or any other living thing.

But a little bit of
phosphorus can go a long way

at producing algae in
a freshwater ecosystem.

1 pound of phosphorus
can magnify itself

into 500 pounds of algae.

That's a huge ratio.

It, naturally, in Wisconsin,

because of our parent
soil materials,

we did not have a lot
of natural phosphorus.

Our lakes in a
pre-settlement condition were

very, very low for the
most part in phosphorus.

It leads us to this concept of
limiting nutrient principle.

That simply is that the
nutrient in least supply

in that lake ecosystem
or freshwater system,

will control the amount
of plant or algae growth,

and we often relate
this just to algae.

So if we only have about
10 times as much nitrogen

as we do phosphorus in the lake,

then we say the lake
is nitrogen limited,

but when we're in 15 times
more nitrogen than phosphorus,

then really phosphorus is doing,

it's that gray area in between.

But this was really not
well understood really until

the 1970s and there
was great debate.

You think back 40, 50 years ago,

why was that important
because we just

take for granted that
we can deal with this.

Back in those days, all of our

cleaning solutions
across the world,

phosphorus was a major
constituent in them.

And the soap and
detergent industry

really wanted to protect that
ability to maintain phosphorus

and we hadn't really gotten
into this understanding of

well, we should be
morphing our products

into more healthy things
that help us live our lives.

So there was great debate going
on all across the country.

There was a camp
saying it was carbon,

another camp of scientists
saying it was nitrogen,

and then there was a group
talking about phosphorus,

so this was really put to
rest in the early 1970s

by a Canadian researcher
named Dave Schindler

as a young graduate
student or young professor,

up doing his work in
Laurentian Shield in Canada,

and with lakes,
they simply did was

took this lake, it was Lake 227,

put a plastic curtain there
across the middle of the lake

that goes all the
way to the bottom,

and he fertilized
both sides of the lake

with nitrogen and
carbon, so there was

plenty there to sustain algae.

And so then what he simply
did is then augmented

one side of the lake
with phosphorus,

and that was the
response Dave got

and it got kinda put
the whole issue to bed.

It is, most of our
lakes, phosphorus

does control algal growth
in most of our lakes

and we feel that in Wisconsin,

over 90% of our lakes
are phosphorus limited.

So it's the one we're
really concerned about.

How we manage that on
the land and in the lake

will control the amount of
algae and the type of algae

you'll get in your lakes.

So soon after that, there
was many, many people

across the world
and the country,

started trying to figure more
of these relationships out,

and this is a very
basic relationship

and it simply is, as
you put more phosphorus

into a lake ecosystem, you
will drive more algae growth

and this is a log-log scale,

so people that understand math,

this is a lot of
noise around here.

We have many, many
mathematical simulations

and variations of that,
that really help us

determine how far do we need

to reduce those
phosphorus levels in lakes

to restore ecosystem health.

So we spent a lot
of time on this.

When I was originally
hired to work

for the DNR, back
in the early '80s,

it was one of my jobs

to understand these
relationships in streams

and people were working
on this in lakes.

So, we finally got to developing
water quality criteria

for lakes in Wisconsin,
30 years later in 2011.

So why do we develop criteria?

Well, it's when we have
obvious water quality problems

and we know they're caused
by excess nutrient loading,

we need to know
how clean is clean,

where do we need to manage
that system back to,

and those goals that then
directly relate to them.

We have numbers that
we know can protect

recreational fish and aquatic
life uses and those things,

and also EPA said this
would be a good thing

for all the states to do.

And these are our criteria
for lakes in Wisconsin.

So those two-story fishery lakes

where we wanna
maintain the integrity

of that dissolved oxygen,

and those deep lakes
below that thermocline,

that stratified layer,

they are very sensitive
to phosphorus.

We'll give them a very low
number, 15 micrograms per liter.

To maintain those
stratified lakes,

those deeper ones,
those higher quality lakes

that I talked about,

that's 20 micrograms per liter.

These are very,
very low numbers.

These are parts per billion,

so if we had a billion ping
pong balls in this room,

to maintain integrity
of a stratified lake,

only 20 of them
could be represented

as phosphorus molecules,

so these are very,
very low numbers.

And so, as the lakes become
less sensitive to phosphorus,

as we get up into those
reservoir systems,

those numbers we have developed

are 40 micrograms per liter
which is twice as much

as what would be
in a seepage lake.

So let's think about now,
how does this impact

the biology of the system,
right?

So what we really want to have,

we gotta create this food
web through the system.

And so what we want are

the high quality algae
species in the system

that can go up into our
invertebrate population,

that little guy in the middle
there is called a zooplankton.

We have many, many species
of those in our lakes,

and they're the guys that
are the energy transformers.

They're taking
those algae cells,

turning them into meat protein,

and then they will be harvested
by fish that eat them,

often our panfish or some of

our minnow species
is a good example.

So we have all this biology
going on in our lake ecosystems.

So what does that primary
function of that algae?

Well one of the
first things it is,

is that energy source for
our invertebrate community,

those filter feeders,
we call them.

But they also produce oxygen.

We surely need oxygen
in our systems to sustain us.

But it's the type
of algae we have.

As long as we stay with
these types of algae

over in the lower type, these
are smaller-celled algae,

our lakes' ecosystem health
remains in a high quality state.

But when we put too many
nutrients into this system,

we shift from this algae
population dominated to

a blue-green algae
population,

so we call those cyanobacteria,
blue-green algae.

As you increase the phosphorus
concentration in our lakes,

we increase that
lake's capability,

we make that nutrient
more available,

we want all those other algae,
different genera of algae

to be in our lakes that
are smaller cellular algae.

They don't create the
nuisance algal blooms.

But you can see there's
a transition right there

in many lakes around that
20 microgram per liter number.

Soon as you get above
20 micrograms per liter,

you start to create a situation

where blue-green algae dominate
in our lake ecosystems.

These are both pictures
that have come from--

Picture on the left is an
algae bloom on peat oil flowage.

That's one of my
co-workers on the right,

that is in Tainter Lake,
over near the city of
Menomonie.

These lakes have the
ability to produce

very, very high levels
of blue-green algae.

And what blue-green algae,
some species

at some times during
their life stage,

we're trying to figure
out what trips us,

they can produce toxicity.

That's what probably killed
that goose in the left.

But these toxins can be
harmful to us, our pets,

if we get to these high levels.

When these cells die,
they release

the toxins into the water.

These are just some
of the characteristics

associated that can
be how they impact us.

We can get dermal reactions.

We have had many folks over
in the Tainter Lake system

that are very prone to it,
that'll get rashes.

One of our staff people was
loading a boat one time,

by the time
she got back to the lab,

showered up and everything,
she got home

and she had this incredible rash

on the lower portion of her leg,

where she had been
in contact with that water.

Neurotoxins, when you hear
of dog deaths sometimes,

or cattle deaths in farm ponds,
they ingest that water.

It can be a very rapid
death for some of those,

and then we also have
hepatotoxins, blood impacts,

where it impacts liver function,

so if you see water
quality characteristics

that look bad, just stay out,

cause there could be
blue-green algal toxicity.

So let's switch here, I mean,
I guess, just again show

this invertebrate communities,

an important part of
our lake ecosystem,

and it is one of those
that energy transfer.

This is the zooplankton,
the daphnia on the left.

That is lunch for
"young-of-the-year" fishes,

that's what they're after.

And if we have a high
quality algae population,

high quality zooplankton,
there's a lot of energy there

to produce a lot of fish
biomass up the food chain.

Aquatic plants, incredibly
valued in our lake ecosystem,

as long as, again, that
system is in balance.

They are absolutely
critical habitat

for many of our aquatic
species that live in lakes.

They are great
physical structure

and are energy dissipaters
and they produce oxygen.

Fish, I think this is what
we all kind of relate to

when we think about this.

As long as we have good
habitat, good water quality,

we tend to have
high quality fisheries,

and some of those
highly impacted lakes,

that Cedar Lake that
I was talking about,

we went through a period of
time there where the fishery,

probably 95% of the fish biomass

in the lake was tied up in carp.

It was also a huge
impact on water quality.

Our rough fish
have very short gut tracts.

They eat the benthos,
the bottom invertebrates

off the lake, and
what they can do is

they actually take
those invertebrates

and sediments from the bottom,

put them through the gut tract,

make many nutrients available,

and they can be a
source of nutrients,

posing a poor water
quality problem.

When we looked at
Cedar Lake back then,

we thought about 30% of
the water quality problem

in the lake was simply
due to the mass of carp

that was in that system.

They were putting thousands
of pounds of phosphorus a year

into the photic zone, the area
where light is in the lake,

to create the algal blooms.

They were a big
factor in that issue.

So, again, all these critters
need high quality habitat.

These are the views and
those characteristics,

those services we want to
maintain in those lakes.

We'll talk a bit about habitat.

That near shore habitat,
we call the "littoral zone"

is where the light penetrates
deep enough into the water

to allow aquatic plants to grow

shoreward from that, and
then up onto the lake shore.

So when we just think
about that littoral zone,

or the area where light
penetrates deep enough

to stimulate the growth
of aquatic plants,

over 90% of the species
in any given lake

are dependent on that
critical habitat component

for at least some component
of their life history.

So if we can maintain
the integrity of that,

we often maintain the
integrity of the system.

And then shoreward from that,

that shoreland buffer zone
area is absolutely incredibly

valuable for aquatic
life near shore,

water-dependent wildlife
and water quality of the lake.

So how have we
developed our lakes?

And how have these impacts
impacted our lake ecosystems?

I'll try and finish up here.

Oh, sorry.

As we think about
this, we look at,

this is what our lake
shores often looked like

in an undeveloped state.

We had emergent vegetation
out the submergent.

Natural woody vegetation
on the shore.

As we have brought
our societal values

and how we live
in our communities,

you know, this is what
we've often brought to these,

and so, when we bring that
type of pattern of development,

we lose these natural ecosystem
functions to our lakes.

So how does that
impact our lakes?

So one of the things
we've looked at,

we have a compendium of
literature that's been developed

in the '90s and through the
early 2000s in Wisconsin,

but they all kind of
show the same thing.

With the way we develop
our lake shores,

once we get to about
30 homes per mile,

we have lost many of
the ecosystem services that

that nearshore and that shallow
water area provides.

And this happens to be
a green frog study.

Once you get about to
that level, there is no
longer

the characteristics there
at a high enough level,

and our green frogs are gone,

but it also shows up
in other areas.

This is coarse woody
habitat, we call it.

It's wood in the lake.

And this is a very valuable
ecosystem function,

providing diversity of
habitat, diversity of refuge

on that wood that's growing,

and there is a
thin layer of algae

which has a lot of
inverts growing on it

which a lot of small fish
come in and pick off.

Big fish come in
there to the prey,

little fish come in there
to get away from big fish.

But again, when we get out
around that 30 homes per mile,

we lose this ecosystem
service in our lakes.

This is Dan Schindler's work,

he happens to be the
son of Dave Schindler.

He was one of our grad students

at the Center for Limnology
back in the late '90s.

And what Dan started looking at,

so how does this
impact fish growth

if we don't have that
high quality habitat

in our lake ecosystems
in the north?

And what he really showed was

fish in lakes with
good woody habitat

have growth rates
of three times more

than lakes where
we've lost that.

So if you turn that
around, you could say

one way we've
developed our lakes,

we've lost about
a factor of three,

or if we had that high quality
habitat in our systems,

our fisheries' production
would be improved

by as much as 300%.

It's a huge number.

So, finishing up
with talking a bit

about how land use impacts

and watershed
impacts water quality.

We think about that and
natural lake ecosystem,

when that water falls on back
to the hydrologic cycle slide,

only about 10%
of that water would runoff.

50% of it would go in

and contribute to
sustaining
ground water levels.

So when we urbanize
an area, especially,

we flip that totally around.

In an urban area, we
only maybe infiltrate

15% of the rainfall
and we runoff 55%.

That 55% running off is a
huge transport mechanism

for phosphorus sediment
and other pollutants.

So our challenge as managers is

how do we take a system like
the picture up on the left,

but make it function
like one on the right?

And we can do this,
it's not that big a deal.

But we have to value
that function, as a society,

before we can do that.

So when we think about this,

we have a variety of models,

but when we as scientists
talk about runoff

or how much pollutant loading
comes from a given land type,

in a natural state,
our landscape,

that one on the lower right,

that forested area
or low density urban,

that only loads pollutant
phosphorus to a water body

at about

0.1 kilograms
per hectare per year.

You can flip that right into
pounds per acre per year,

if that's easier
to think about it.

But by the time we
get to mixed ag,

or high density urban,
we've increased that

by an order of magnitude,
by about ten-fold.

This is a new tool that's out
there for any of you folks.

Go see Matt Diebel's talk in
the next session after plenary,

but what Matt has put
together for us now

for all lakes in Wisconsin--

That happens to be Cedar Lake
down there in the bottom.

And through GIS techniques
and digital elevation models,

we can computer generate what
your water shed looks like now

and the land use
characteristics of it.

And the reason Matt put this
together for us on Cedar Lake

is that, I think he's got
some place here, I thought--

oh, the phosphorus load,
most likely

because of the amount
of agriculture in there,

this watershed,
he estimates to be loading

about 0.5 pounds
per acre per year,

most likely,
at 13,600 pounds a year.

Well, because of the farmers

in this watershed have
cooperated fantastically

with their lake shore neighbors,

this watershed
only is functioning

at a factor of about
0.2 pounds per acre.

And it shows we can
manage the runoff

in these agricultural
ecosystem watersheds,

so their amount of phosphorus
coming off the land

is only two times
above background.

That's a phenomenally low number

for an agricultural
dominated watershed.

And so how does that ag
source area get on there?

Well, we put it on there through
what we've fed our cattle.

After World War II, we've
had a lot of our dairy cattle

on enriched phosphate
mineral that showed up

through their
manure that has been

on their land for decades.

Farmers have really since,
I would say, the late '90s,

no longer feed, we found
we don't need to feed that.

And then of course,
inorganic fertilizers,

and farmers are doing a
tremendously better job

of really putting on that
fertilizer based on crop need

and managing their
land off in a way

so it doesn't generate runoff.

Here's just a fact
from Lake Mendota.

This is Elena Bennett's
master's research

for Center of Limnology
back in the mid '90s.

What Elena did was
put together a mass balance

for how much phosphorus
did we put on the land

in the Lake Mendota watershed?

Well, this is 1,300 metric tons,

so there's 2,200 pounds
in a metric ton.

That's a few million pounds
of phosphorus a year.

And then, how much really
do we use of that phosphorus

to produce the meat commodities?

A little over half of that.

So we were storing,
back in pre-1995 conditions

of Lake Mendota, we were
just mass accumulating

phosphorus on the landscape

of over a million pounds
a year, 575 metric tons.

It's a huge number.

So we have learned
from these situations

and we're doing
much better today.

Residential development, boy,
that has impacted our lakes,

especially from new channeling.

How we develop property
when we develop

or rebuild a home, we totally
destroy the soil health,

the soil structure, by putting
all this equipment around.

We virtually eliminate
often, or severely reduce

the ability of that soil
to infiltrate water.

We fertilize our yards,
we grade our yards

to make them highly efficient

to get that storm water run
off away from the buildings.

So we did a little
work, John Panuska,

he did this work for us
when he worked at DNR.

He's now over at the university.

John did some modeling for us

so we took an
individual lake slot.

We wanted to simulate a lot up

on Long Lake in Chippewa County.

So in a natural condition,

before we did any development,

John simulated that
this slot would generate

about 1,000 cubic feet
of runoff of water,

3 hundredths of a pound
of phosphorus

and 5 pounds of sediment.

So the first property that
was built on this lake

was post-World War II,
where we had,

this is what we were building.

This happens to be
the Laine Cabin, up on a lot.

And so when Grandpa
Laine came up

on the train from Chicago
in the summer,

he built a cabin,
built a cottage,

and what was that impact?

Well, that impact,
he really didn't impact

cause we weren't putting
much impervious surface down,

we weren't disturbing
much of the lake life,

so we maintained most

of those natural
hydrologic characteristics
of that landscape.

So things changed a bit when
the Laines sold the property

and the boom in the
market in the '90s.

This is a very modest home
by those standards,

but it really changed things up
on that lot.

So we went almost to 4,000
square feet of imperviousness.

We had to get around on that
lot to build that house,

and so we impacted runoff,
we predicted five-fold increase.

In phosphorus, about
a seven-fold increase.

Our lakes cannot
sustain these types

of increased inputs
if we don't manage them.

Okay, so this is just a shot

as we increase
that imperviousness.

Once we get to even as
little as

15% of the lot is covered

with rooftops, sidewalks,
walkways, driveways,

you've increased
the mass loading of phosphorus

from that parcel of land
by a factor of six.

And so, with that, I'm done.

Thanks, folks.

(applause)