Perspectives on the Phosphorus
Problem in Lake Champlain
Eric Smeltzer
[email protected]
Why is phosphorus a problem in lakes?
Low
Phosphorus
~10 µg/L
High
phosphorus
Medium
phosphorus
Very high
Phosphorus
> 50 µg/L
Why are excessive algae a problem in lakes?
•
•
•
•
Impair recreation and aesthetic enjoyment
Impair water supply
Alter the ecosystem
Blue-green algae (cyanobacteria) can be
toxic
A blue-green algae (cyanobacteria) bloom
X
Phosphorus concentrations and trends in Lake Champlain
Sources of phosphorus loading to Lake
Champlain, 2007-2008
Vermont nonpoint sources (68%)
Vermont wastewater (2%)
Quebec nonpoint sources (8%)
Quebec wastewater (<1%)
New York wastewater (3%)
New York nonpoint sources (19%)
Phosphorus Load Discharged (mt/yr)
Long-term trends in Vermont wastewater
phosphorus loads to Lake Champlain
250
Phosphorus detergent law
0.8 mg/l effluent concentration limit
200
2002 Lake Champlain TMDL
150
Dishwasher detergent law
100
2002 TMDL Limit
50
(18.4)
0
1975 1980 1985 1990 1995 2000 2005 2010
Long-term trends in phosphorus loading to Lake
Champlain from all sources
12000
1200
10000
3
1000
Gaged Flow (hm /yr)
Phosphorus Load (mt/yr)
1400
8000
800
6000
600
4000
400
2000
200
0
0
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
Nonpoint Load
Wastewater Load
Gaged Flow
TMDL Target Load
Lake Champlain Basin Land Use
Phosphorus loading to Lake Champlain by land use type
Why does it take so long to see
results?
It takes several years for vegetation to become
established.
Phosphorus has accumulated in the soils of some farm fields after decades of
over-fertilization. It can takes many years for soil phosphorus concentrations
to decline even after proper nutrient management methods are implemented.
Federally-subsidized superphosphate (in tons) brought into Vermont for
farmers to apply to fields.
14000
12000
10000
8000
6000
4000
2000
19
3
19 6
38
19
40
19
42
19
44
19
46
19
48
19
50
19
53
19
5
19 6
58
19
60
19
62
19
64
19
66
19
68
19
70
19
72
0
Deforestation and over-grazing in Vermont
during the 19th century caused
tremendous erosion of upland soils.
Images from the Landscape Change Program
There is an historical legacy of alluvial sediments deposited along Lake
Champlain Valley rivers. These sediments are continuing to erode, and even
with proper river corridor protection measures in place, it will be decades
before stream stability is fully restored.
Decades of excessive phosphorus loading can create the conditions for
internal phosphorus loading in places like St. Albans Bay and Missisquoi
Bay. Internal loading delays the recovery of the bay in response to load
reductions from watershed sources.
Changing farming practices and other landowner behavior sometimes
takes the transition of a generation.
It’s going to be a marathon…..
….not a sprint!
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Phosphorus Impacts in Lake Champlain