lake science basics · 2018-01-22 · lake science basics “everything should be made as simple as...

Lake Science Basics

“Everything should be made as

simple as possible, but not simpler.” Albert Einstein

Lake Management Workshop

Polk County Association of Lakes and Rivers

Polk County Land & Water Resources Dept.

Topics

PCALR 2013

• Background fundamentals

• Lake quality influencers

• Lake quality measurement

Background Fundamentals

• Lake science - a tool

• What is lake quality?

• Lake formation & aging

• Water & nutrient cycling

• Terminology

PCALR 2013

Does Your Lake Satisfy Everyone?

Lake Science: a tool to aid in

• learning a lake’s capacity to satisfy

people’s desires

• determining actions to maximize

satisfaction

• maintaining a match between lake’s

capacity and people’s desires

PCALR 2013

Perception of Lake Quality Varies

• Good clarity

• Not too weedy

• Fishing success

• Pleasing shoreline

• Great nature experience – wildlife, plants…

• Non-toxic water

• Safe and considerate use

• Not too much noise or light

• No overcrowding (boats & people)

• Lake level just right

• Enjoyable watersports

• Good company

PCALR 2013

Water clarity?

PCALR 2013

“Less Weeds”?

PCALR 2013

Pleasant Scenery?

PCALR 2013 Source: UW Extension

Less Business?

PCALR 2013 Source: Andy Loree photo

No Bad Invisible Stuff?

PCALR 2013

Often Unnoticed Good Stuff?

PCALR 2013

Polk County Lake History

• Age of earth – 4.5 billion years

• Glaciers 10000-30000 years ago

• Lake aging since last glacier period

PCALR 2013

Area covered by last ice age

PCALR 2013 Source: NOAA

Border shown is about 15000 years ago

Polk County Glaciers

PCALR 2013

Glacier Lake Formation

PCALR 2013 Source: NYSFOLA

Natural vs Cultural Aging


Cultural Eutrophication (accelerated aging)

The excessive addition of

• Inorganic nutrients

(phosphorus and nitrogen),

• Organic mater

(live & dead plants & animals),

• and silt

(soil particles)

to a lake.

PCALR 2013

PCALR 2013 Source: Steve Carpenter, UW

Cultural Aging Sources


Hydrologic Cycle

PCALR 2013 Source: Sorge WDNR

Lake Life Cycle

PCALR 2013

Settling & Decomposition

PCALR 2013

algae

alg

ae d

ie &

settle

to b

ott

om

decay uses up oxygen &

produces nutrients

Food Web

PCALR 2013 Source: Managing Lakes & Rivers 2001

Lake Zones


Littoral Zone


Dissolved & Suspended Particles

PCALR 2013

Pure water

Dissolved material

no settling

Dissolved and suspended material

Large particles – rapid settling

Small particles – slow settling

Nutrient Concentration and Loading

PCALR 2013

1 tsp per glass (concentration)

3 tsp per glass (concentration)

= 9 tsp load to lake and

3 glasses of liquid flow

to the lake

= 15 tsp load to lake and

15 glasses of liquid flow

to the lake

IMPORTANT: both nutrient concentration AND amount of flow to a lake

Topics


• Lake quality influencers Physical

Chemical

Biological

Shoreland & Littoral Zone


PCALR 2013

Physical Influencers

• Area (lake and watersheds)

• Retention time

• Type

• Position in landscape

• Depth

• Temperature

• Mixing

• Shape

PCALR 2013

“Sheds”

PCALR 2013

Runoff

Watershed

“Sheds”

PCALR 2013

Runoff

Watershed

Groundwater

Watershed

“Sheds”

PCALR 2013

Runoff

Watershed

Groundwater

Watershed

Direct Precipitation

Watershed

Watershed Size


Lake Surface Area = 100 acres More runoff

More sediment and nutrient loading

Shorter hydraulic retention time

Lake Surface Area = 100 acres Less runoff

Less sediment and nutrient loading

Longer hydraulic retention time

Retention Time


3 million gal/day

150 million gal ÷ 3 million gal/day ꞊ 50 days

3 million gal/day

150 million gal

Retention Times

PCALR 2013

North Pipe Lake – 1.5 years

Pipe Lake – 10.1 years

Seepage Lake


Drainage Lake


Impoundment Lake


Landscape Position


Depth Effects


Deep Lakes

Stratify

Shallow Lakes

Continuous

Nutrient

Recycling

Mixing (overturn) & Stratification

PCALR 2013 Source: WDNR

Shape

PCALR 2013

wind direction

Wind will mix up

the longer lake

the most.

Irregular shapes

have twice as

much shoreline to

develop & add

nutrients to lake

Chemical Influencers

PCALR 2013

Macro nutrients

Carbon

Hydrogen

Nitrogen

Oxygen

Phosphorus

Characteristics

Total suspended solids

pH (acidity)

Conductance

Color

Hardness

Alkalinity

Dissolved gases

Carbon dioxide

Oxygen

Nitrogen

Some other important elements

Sodium

Sulfur

Magnesium

Silicon

Potassium

Magnesium

Iron

Calcium

Most Wisconsin Lakes

Phosphorus Limited

PCALR 2013

Lake 226, Ontario, Canada

carbon & nitrogen added

carbon, nitrogen &

phosphorus added

Source: Experimental Lakes Area, Canada

Land Use


Land Cover Total Phosphorus

Export

kg/ha/yr

High Density Urban 1.5

Row Crop Agriculture 1.0

Mixed Agriculture 0.8

Grass / Pasture 0.3

Medium Density Urban 0.5

Low Density Urban 0.1

Forested 0.09

Phosphorus export coefficients - developed based

using monitoring data.

WISCONSIN VALUES

Big Butternut Lake Nutrient Budget

PCALR 2013 Source: Polk County LWRD

Note: Internal load

not included Pasture/grass

12%

High density

residential

41%

Medium density

residential

1% Rural residential

1%

Wetlands

8%

Forest

22%

Lake surface

15%

Nutrient Load Sources

• External

o Runoff watershed

o Groundwater watershed

o Direct precipitation

• Internal - Phosphorus (P) released from sediments

o With mixing, phosphorus may increase in surface water

o Without mixing, oxygen loss prevents fish & zooplankton

from living in lower water zone

PCALR 2013

P

Biological Influencers

• Producers

o algae

o plants

• Consumers

o Fish & other vertebrates

o zooplankton & other invertebrates

• Decomposers

o bacteria

o fungi

o detritivores

PCALR 2013

Algae

Food for small fish

and zooplankton.

A few species are

toxic.

PCALR 2013 Photo Source: WI Lake Partnership

Aquatic Plants • Habitat (protection for

animals)

• Prevents shore erosion

• Absorbs nutrients

• Some are invasive

PCALR 2013 Photo Source: Czarapata, WI Lake Partnership

Consumers

PCALR 2013 Photo Source: WI Lake Partnership

Decomposers

PCALR 2013

Scud

Bloodworm (midge) larva

Bacteria

Carp

Fungi

Shoreland & Littoral Zone Modification

Examples

• Woody Habitat

• Green Frogs

• Lake lots

PCALR 2013

Shoreland Trends - Woody Habitat

PCALR 2013

log

Growth

Rate

(mm/yr)

Woody Habitat (no./km)

High Development

Low Development

Undeveloped

High Development

Low Development

Undeveloped

From Schindler et al. 2000

Fish grow ~3X faster in lakes with lots of woody habitat

Source: Sorge, WDNR

Shoreland Trends – Green Frogs


Undeveloped Lot: Apr.-Oct. phosphorus/sediment runoff model


1940s development: Apr.-Oct. phosphorus/sediment runoff model



Today’s development: Apr.-Oct. phosphorus/sediment runoff model

Shoreland Development Trends

April – October phosphorus/sediment runoff

20000 sq-ft lot Undeveloped

forest

1940s

development

Today’s

development

Gallons runoff

to lake

7500 7500 37400

Pounds phosphorus

to lake

0.03 0.03 0.20

Pounds sediment

to lake

5 20 90


Lawn Vs Forest Study

PCALR 2013 Source: USGS & WDNR

Phosphorus runoff

from a shoreland lawn

averaged 8 times

more than

from adjacent forested

shoreland

Study Area

Topics


• Lake quality influencers


PCALR 2013 CLMN Manual

Secchi Depth

• Visibility threshold

• Simple

• Inexpensive

• Measurement

variability

PCALR 2013

Samplers & Sensors

PCALR 2013

Dissolved oxygen,

Temperature

For phosphorus sampling

below surface waters

For surface sampling of

phosphorus & chlorophyll

Source: WDNR

Basic Measurements

• Secchi depth

Low cost clarity measurement

Rough indicator of eutrophication degree

• Total phosphorus

More means more algae - usually

• Chlorophyll

Estimates amount of algae

• Dissolved Oxygen

Determines depth for lake animal survival

Helps keep phosphorus in sediments

• Temperature

Depth profile gives stratification measurement

Higher temperature encourages algae growth

PCALR 2013

Trend Charts

PCALR 2013 Wisconsin Citizen Lakes Monitoring Network

Trend Charts

PCALR 2013

Phosphorus Effect Anomalies

PCALR 2013

R2(all points) = 0.002

Measurements for More Thorough Understanding

Dissolved phosphorus

Color

pH

Alkalinity

Hardness

Nitrogen (organic and inorganic forms)

Micronutrients

Paleolimnology

Algae type and amount

Plant survey

Zooplankton

Streams – flow rate, nutrient conc., biological index

Toxins

Depth profiles

Spring/winter/fall basic set

PCALR 2013

Point Intercept Aq Plant Survey

PCALR 2013 Source: Polk County LWRD

Paleolimnology


Measurement Records

• Statewide –

Citizen Lake Monitoring Network Database

• Local record set –

Critical for effective lake management

• Review annually for relationship to goals

PCALR 2013

Useful References

• Understanding Lake Data Limnology 101 Basics Limnology 101 Landuse & Watershed Impacts Limnology 101 Biotic Interactions & Habitat pcalr.org/library/#lake-citizen-science

• Understanding Lakes lakeaccess.org/understanding.html

• Lake Ecology – Resources Clearinghouse uwsp.edu/cnr/uwexlakes/ecology

• North American Lake Management Society nalms.org

• New York State Federation of Lake Associations http://www.dec.ny.gov/docs/water_pdf/dietlake09.pdf

PCALR 2013

http://pcalr.org/library/





http://www.lakeaccess.org/understanding.html

http://www4.uwsp.edu/cnr/uwexlakes/ecology/





http://www.nalms.org/home/default.cmsx

http://www.dec.ny.gov/docs/water_pdf/dietlake09.pdf

Lake Science Basics

Questions?

Contact Larry Bresina

[email protected]

lake science basics · 2018-01-22 · lake science basics “everything should be made as simple as...

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