Hart Lake 2009 Annual Report

Volunteer Collector: Josh Teigen

 

Hart Lake -  258 Acres         Approx. Depth: 54 ft.

Lake Type: SEEPAGE

Bayfield County

DNR Region: NO

Waterbody Number: 2903200

GEO Region:NW

 

Site Name

Storet #

Hart Lake (T47n R08w S27) - Deep Hole

043079

 

Date

SD

(Secchi depth)
(ft)

Hit
Bottom

TSI

(Trophic State Index)
(SD)

Lake
Level

Clarity

Color

Perception

06/14/2009

25.5

NO

30

NORMAL

CLEAR

GREEN

1

 

07/13/2009

22.5

NO

32

NORMAL

CLEAR

GREEN

1

 

07/26/2009

25.5

NO

30

NORMAL

CLEAR

GREEN

 

1

08/05/2009

22

NO

33

NORMAL

CLEAR

GREEN

1

 

08/13/2009

22.5

NO

32

NORMAL

CLEAR

GREEN

1

 

08/24/2009

21.5

NO

33

NORMAL

CLEAR

GREEN

1

 

09/07/2009

24.5

NO

31

NORMAL

CLEAR

GREEN

1

 

09/23/2009

21.5

NO

33

NORMAL

CLEAR

GREEN

1

 

 

Date

Collector Comments

08/05/2009

Partly cloudy and a nice chop on the lake.

08/13/2009

Sunny.....no clouds

08/24/2009

Sunny.....no clouds

09/23/2009

Sunny and a little chop on the water

 

 

 

 

 

 

 

Average Summer (July-August) Secchi Readings by Year

 

 

Hart Lake

Lake Type: SEEPAGE

Bayfield County

DNR Region: NO

Waterbody Number: 2903200

GEO Region:NW

 

 

 

Avg July-Aug Secchi Depth (ft)

 

5

10

15

20

25

30

35

40

 



19

  1993



21

  2004



18

  2007



23

  2009

           


Past secchi averages in feet (July and August only).

Year

Secchi Mean

Secchi Min

Secchi Max

Secchi Count

1993

19

19

19

2

2004

20.8

19.75

22

5

2007

18.5

15.7

21.3

4

2009

22.8

21.5

25.5

5

 

 

 

 

 

 

Hart Lake  Annual Narrative Report - 2009


oligotrophic

Hart Lake (T47n R08w S27) - Deep Hole was sampled 8 different days during the 2009 season. Water clarity was sampled with a secchi disk. Taking Secchi readings is just one means of monitoring the health of a lake.  Combined with temperature readings, chemistry testing of chlorophyll, phosphorus, & dissolved oxygen during the warm months, we get a more accurate picture of its overall water quality.

The average for the Northwest Georegion was 9.7 feet. The average summer (July-Aug) secchi disk reading for Hart Lake (T47n R08w S27) - Deep Hole (Bayfield County, WBIC: 2903200) was 22.8 feet which is considerably higher than the average. Typically the summer (July-Aug) water was reported as CLEAR and GREEN.

 

 

 

 

 

 

 

 

Trophic State Index Report – 2009

 

Trophic state index (TSI) is determined using a mathematical formula (Wisconsin has its own version). The TSI is a score from 0 to 110, with lakes that are less fertile having a low TSI. We base the overall TSI on the Chlorophyll TSI when we have Chlorophyll data. If we don't have chemistry data, we use TSI Secchi. We do this rather than averaging, because the TSI is used to predict biomass, or living organisms in an environment such as a lake. This makes chlorophyll the best indicator. Visit Bob Carlson's website, dipin.kent.edu/tsi.htm, for more info.

 

The overall Trophic State Index (based on Secchi) for Hart Lake (T47n R08w S27) - Deep Hole was 32. The TSI suggests that Hart Lake (T47n R08w S27) - Deep Hole was oligotrophic. This TSI suggests deeper lakes, are characterized by very high Secchi depths, plenty of oxygen in deep water, and may have cold-water fish species living in them.

 

 

 

Past Summer (July-August) Trophic State Index (TSI) averages.

Trophic State Index Graph

Hypereutrophic


100

90

80

70

Eutrophic

60

50

Mesotrophic

40

Oligotrophic

30

20

10

0

 

 

 

 

 

 

 

 

Chl TSI: 35TP TSI: 39

 

1991

 

 

 

 

 

 

Secchi TSI: 35

 

 

1993

 

 

 

 

TP TSI: 44

 

1997

 

2003

 

 

 

 

 

Secchi TSI: 33

2004

     

 

 

 

 

TP TSI: 44

Secchi TSI: 33Chl TSI: 35

     

2007

  

 

 

 

 

 

 

       

2008

 

 

 

 

 

Secchi TSI: 32

2009

 


= Secchi     = Chlorophyll     = Total Phosphorus

 

TSI(TP) = TSI(Sec) > TSI(Chl)

Non-algal particulate or color dominate light attenuation

TSI(Sec) = TSI(Chl) >= TSI(TP)

The algae biomass in your lake is limited by phosphorus

TSI(TP) > TSI(Chl) = TSI(Sec)

(2007)

Zooplankton grazing, nitrogen, or some factor other than phosphorus is limiting algae biomass

 

TSI

TSI Description

TSI < 30

Classical oligotrophy: clear water, many algal species, oxygen throughout the year in bottom water, cold water, oxygen-sensitive fish species in deep lakes. Excellent water quality.

TSI 30-40

Hart Lake

Deeper lakes still oligotrophic, but bottom water of some shallower lakes will become oxygen-depleted during the summer.

 

 

Understanding Your Lake Data:

 

For more information about understanding your lake data as it relates to water clarity, click on the following link and go to Page 79. 

 

http://dnr.wi.gov/lakes/CLMN/manuals/0910chem/ChemistryMan76-91.pdf

 

 

If you have any questions, please contact Jane Swenson, swensonje@cheqnet.net