pH
The pH of a lake
reflects how acidic or basic the water is and helps determine which
plant and animal species are present. The measure of the acidity is on a
scale of 0-14, with 7 being neutral. Acid waters are below 7, alkaline
waters are above 7. pH of lakes vary in Maine from 4.45 to 9.35, the average is
6.7. A one unit change in pH represents a 10 fold change in acidity or
alkalinity.
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The pH scale with common substances |
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pH Value Limits
|
|
Minimum |
Maximum |
Effect |
|
3.8 |
10.0 |
Fish eggs can be hatched, but deformed
young often produced |
|
4.0 |
10.1 |
Limits for most resistant fish species
|
|
4.1 |
9.5 |
Range tolerated by trout |
|
4.5 |
9.0 |
Trout eggs and larvae develop normally
|
|
4.6 |
9.5 |
Limits for perch |
|
5.0 |
--- |
Limits for stickleback fish |
|
5.0 |
9.0 |
Tolerable range for most fish
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|
--- |
8.7 |
Upper limit for good fishing waters
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|
5.4 |
11.4 |
Fish avoid waters beyond these limits
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6.0 |
7.2 |
Optimum (best) range for fish eggs
|
|
1.0 |
--- |
Mosquito larvae are destroyed at this pH
value |
|
3.3 |
4.7 |
Mosquito larvae live within this range
|
|
7.5 |
8.4 |
Best range for the growth of algae |
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Water ,Water Everywhere; Hach
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Care to Compare?
The data used to create this graph were provided
to PEARL by the Maine Department of Environmental Protection
(DEP). DEP summary data were
used, which can be viewed by clicking "Browse Data Sets" then
the "Water Quality" button from PEARL's homepage. The distribution of mean (or
average) pH levels recorded at 863 sampling sites are shown. Need data?
You can search for a lake or pond
from the PEARL homepage.
Out of 863 sample stations:
|
pH reading |
Number of sample
sites with readings in this range |
Percentage of
sample sites with readings in this range |
| 4 - 4.9 |
6 |
0.7 |
| 5 - 5.9 |
29 |
3.4 |
| 6 - 6.9 |
501 |
58.0 |
| 7 - 7.9 |
313 |
36.3 |
| 8 - 8.9 |
13 |
1.5 |
| 9 - 9.9 |
1 |
0.1 |
- 6, or 0.7%, had pH readings of 4 - 4.9
- 29, or 3.4%, had pH readings of 5 - 5.9
- 501, or 58%, had pH readings of 6 - 6.9
- 313, or 36.3%, had pH readings of 7 - 7.9
- 13, or 1.5%, had pH readings of 8 - 8.9
- 1, or 0.1%, had pH readings of 9 - 9.9
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