Find lake

Click the Find lake button and a field will appear in which you can write the lake's name or a part of it. Click the Submit button and all the lakes that correspond to your search will be listed. Select the right lake by clicking Select from the end of the row. After this, you will get all the basic information about the lake automatically into the data form. If your lake is not on the list, return to the data form and fill in all the basic information yourself.

Lake name

First try if your lake can be found from the LLR-database (the Find lake button) If not, fill in lake name and all the other basic information.

Volume

Lake volume in cubic meters.

Mean depth

Lake mean depth in meters.

Lake type

The number that equals your lake's type. From the table below you can see the Finnish lake types and their characteristics.

Finnish lake types (A = area, z = mean depth)

Type

Code

Name of the type

Characteristics

1

Vh

Small and medium low humic lakes

A < 4,000 ha; color < 30 mg Pt/l; z ≥ 3 m

2

Ph

Small humic lakes

A < 500 ha; color: 30-90 mg Pt/l; z ≥ 3 m

3

Kh

Medium humic lakes

A: 50 - 4,000 ha; color: 30-90 mg Pt/l; z ≥ 3 m

4

SVh

Large low humic lakes

A > 4,000 ha, color < 30 mg Pt/l

5

Sh

Large humic lakes

A > 4,000 ha; color ≥ 30 mg Pt/l

6

Rh

Very humic lakes

color > 90 mg Pt/l, z ≥ 3 m

7

MVh

Shallow low humic lakes

color < 30 mg Pt/l, z < 3 m

8

Mh

Shallow humic lakes

color: 30-90 mg Pt/l, z < 3 m

9

MRh

Shallow very humic lakes

color > 90 mg Pt/l, z < 3 m

10

Lv

Lakes with a very short retention time

Retention time about 10 days or less

11

PoLA

Lakes in northern Lapland

Located above the tree line (of pine)

12

RrRk

Nutrient rich and very calciferous lakes (subtype not defined)

Naturally rich in nutrients or lime

13

Rr

Nutrien rich lakes (subtype of RrRk)

Catchment naturally rich in nutrients

14

Rk

Very calciferous lakes (subtype of RrRk)

High lime content

(Source: Finnish Environment Institute. Instructions for determining the type of the surface water 15.1.2007 (in Finnish).)

 

Data chart

Create an Excel chart and label the columns A-E exactly as in the example below. Make sure you have all the small and capital letters right! Save the chart in csv-format.

To fill in the chart you need the following data about the lake as averages over the lakes retention time:

LN total nitrogen load (kg/d)

LP total phosphorus load (kg/d)

TotN total nitrogen concentration (g/l)

TotP total phosphorus concentration (g/l)

Q outflow (m3/s).

Make sure you have the values in the right units! Try to collect data from as long a time period, and from as many retention periods as possible. You should have data from at least two retention periods, giving a minimum of two rows. If you have loading and concentration values for only one of the other nutrient, you can leave those columns empty and use the option Target load based on good/mod class boundary of TotP or Target load based on good/mod class boundary of TotN for target load estimates.

The retention time used here is the lake's actual retention time rounded up to the next whole year (so the minimum retention time will be one year). Retention time (in days) can be calculated with the equation

where

T = retention time (d)

V = volume (m3)

Q = outflow (m3/s)

 

The load values (LN and LP) are the average daily loads, calculated from the estimated or measured sum loads for the retention time.

The total nitrogen and total phosphorus concentrations (TotN and TotP) are averages for the retention time, but only the values from the growing season (or seasons, if the retention time is longer than one year) are taken into account when calculating the average. If there are concentration values from different parts of the lake, use the ones from the main basin. If samples are also taken from different depths of the basin, calculate first the volume weighted average (if possible) for every sampling occasion with the equation

where

CTot total nutrient concentration (g/l)

Cn the nutrient concentration of the water layer n (g/l)

Vn the volume of the water layer n (from the midpoint of the observation Cn and it's upper observation to the midpoint of the observation Cn and it's lower observation, see figure below.) (m3)

V total volume of the lake (m3)

 

If the sampling interval is longer than the lake's retention time (in years), you can use the values from each sampling occasion as they are. However, carefully consider how representative the values are, as there can be big variation in in-lake concentrations during the growing season.

When you have the data chart ready, click the Browse button, search for the chart file in your directory and choose Open.

If you do not have enough data for the data chart, click the I don't have data button and continue to fill in the new data form that appears.

Loading/Flush

If you do not have the data needed for the Data chart, give an estimate of the daily phosphorus and nitrogen load (kilograms per day) and of the lakes outflow (cubic meters per second).

Color

Lake water color in milligrams platinum per liter (needed only when estimating target loads with the biomass model).

Prediction probability (fixed)

When the prediction probability is 50, there is a 50 % possibility to achieve good water quality with the target loads given by the models. Nevertheless, the possibility of failure is also 50 %. This probability level is always used in all the predictions.

Prediction probability 2

You can make the estimates of the lake specific model more accurate by choosing higher probability levels. For instance with prediction probability 80, the possibility to achieve good water quality is 80 % and the possibility of failure only 20 % (see also Prediction probability (fixed)). You can examine what effect a higher prediction probability has on the target load estimations.

Prediction probability 3

As Prediction probability 2. You can add one more probability level and compare the target load estimations.

Chl-a and nutrient data

If your lake can be found in the LLR-database (see Find lake), the chlorophyll-a and nutrient data needed to run the chlorophyll-a model is also ready. If not, create an Excel chart exactly like in the example below and save it in csv-format. Make sure you label the colums A-C right!

totp = total phosphorus concentration (g/l)

totn = total nitrogen concentration (g/l)

chla = chlorophyll-a concentration (g/l)

To fill in the chart you need surface water concentration values of total phosphorus, total nitrogen and chlorophyll-a from all the sampling occasions that have taken place during the growing season in different years. No averages need to be calculated. If there are concentration values from different parts of the lake, use the ones from the main basin.

When you have the data chart ready, click the Browse button, search thechart file from your directory and choose Open

Target load based on good/mod class boundary of TotP

With this option LLR gives you an estimate of the target phosphorus load with which the in-lake phosphorus concentration reaches the good/moderate class boundary.

Target load based on good/mod class boundary of TotN

With this option LLR gives you an estimate of the target nitrogen load with which the in-lake nitrogen concentration reaches the good/moderate class boundary.

Target loads based on good/mod class boundary of TotP and TotN

With this option LLR gives you an estimate of the target phosphorus and nitrogen load with which the in-lake phosphorus and nitrogen concentration reaches the good/moderate class boundary.

Target loads based on good/mod class boundary of Chl-a

With this option LLR gives you an estimate of the target phosphorus and nitrogen load with which the in-lake chlorophyll-a concentration reaches the good/moderate class boundary.

Target loads based on good/mod class boundary of phytoplankton biomass

In this option LLR gives you an estimate of the target phosphorus and nitrogen load with which the phytoplankton biomass will not exceed the good/moderate class boundary.

Water quality class boundaries

Water quality class boundaries for Finnish lakes

Type

Variable

Class boundaries

 

 

 

High/Good

Good/Mod

Mod/Poor

Poor/Bad

1. Vh

TotP

g/l

10

18

35

70

 

TotN

g/l

400

500

750

1000

 

Chl-a

g/l

4

7

14

28

 

Biomass

mg/l

0,6

1,3

2,6

5,2

2. Ph

TotP

g/l

18

28

45

90

 

TotN

g/l

510

700

1000

1500

 

Chl-a

g/l

7

15

24

48

 

Biomass

mg/l

1,5

3,8

7,6

14

3. Kh

TotP

g/l

18

28

45

90

 

TotN

g/l

540

660

1000

1500

 

Chl-a

g/l

7

12

24

48

 

Biomass

mg/l

1,2

3,3

6,6

13

4. SVh

TotP

g/l

10

18

35

70

 

TotN

g/l

400

500

700

900

 

Chl-a

g/l

3,6

7

13

26

 

Biomass

mg/l

0,5

0,9

1,9

3,8

5. Sh

TotP

g/l

15

25

40

80

 

TotN

g/l

460

600

900

1300

 

Chl-a

g/l

6

11

20

40

 

Biomass

mg/l

0,9

1,7

3,4

6,7

6. Rh

TotP

g/l

30

45

65

120

 

TotN

g/l

590

750

1100

1800

 

Chl-a

g/l

12

20

40

80

 

Biomass

mg/l

1,3

2,4

4,8

9,6

7. MVh

TotP

g/l

15

25

45

80

 

TotN

g/l

480

600

1000

1500

 

Chl-a

g/l

5

8

15

30

 

Biomass

mg/l

1,2

2,3

4,6

9,2

8. Mh

TotP

g/l

25

40

65

100

 

TotN

g/l

600

750

1100

1800

 

Chl-a

g/l

12

20

40

60

 

Biomass

mg/l

1,6

4,4

8,8

17

9. MRh

TotP

g/l

40

55

80

150

 

TotN

g/l

680

850

1400

2200

 

Chl-a

g/l

15

25

50

100

 

Biomass

mg/l

2

5,4

10,6

21,2

10. Lv

TotP

g/l

25

40

70

90

 

TotN

g/l

450

610

900

1400

 

Chl-a

g/l

5

8

20

35

 

Biomass

mg/l

Class boundaries not set

11. PoLa

TotP

g/l

9

12

15

20

 

TotN

g/l

190

300

400

600

 

Chl-a

g/l

3

5

10

20

 

Biomass

mg/l

Class boundaries not set

12. RrRk

TotP

g/l

40

55

75

120

 

TotN

g/l

780

930

1200

1800

 

Chl-a

g/l

12

20

40

60

 

Biomass

mg/l

Class boundaries not set

13. Rr

TotP

g/l

40

55

75

120

 

TotN

g/l

780

930

1200

1800

(savialueet)

Chl-a

g/l

12

20

40

60

(muut)

Chl-a

g/l

7

12

25

50

 

Biomass

mg/l

Class boundaries not set

14. Rk

TotP

g/l

20

30

50

80

 

TotN

g/l

550

750

1100

1600

(savialueet)

Chl-a

g/l

12

20

40

60

(muut)

Chl-a

g/l

7

12

25

50

 

Biomass

mg/l

Class boundaries not set

TotP = total phosphorus concentration

 

TotN = total nitrogen concentration

 

Chl-a = chlorophyll-a concentration

 

Biomass = phytoplankton biomass in June-August

 

 

 

 

 

(Source: Finnish Environment Institute & Finnish Game and Fisheries Research Institute.

Reference conditions for ecological classification of surface waters and assessing the class. 22.1.2008 (in Finnish).)