perspectives on the phosphorus problem in lake champlain
DESCRIPTION
Perspectives on the Phosphorus Problem in Lake Champlain. Eric Smeltzer [email protected]. Why is phosphorus a problem in lakes?. Low Phosphorus ~10 µg/L. Medium phosphorus. High phosphorus. Very high Phosphorus > 50 µg/L. Why are excessive algae a problem in lakes?. - PowerPoint PPT PresentationTRANSCRIPT
Why is phosphorus a problem in lakes?
LowPhosphorus~10 µg/L
Very highPhosphorus> 50 µg/L
Highphosphorus
Mediumphosphorus
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%)
New York wastewater (3%)
New York nonpoint sources (19%)
Quebec wastewater (<1%)
Quebec nonpoint sources (8%)
Long-term trends in Vermont wastewater phosphorus loads to Lake Champlain
1975 1980 1985 1990 1995 2000 2005 2010Pho
spho
rus
Load
Dis
char
ged
(mt/y
r)
0
50
100
150
200
250 Phosphorus detergent law
2002 Lake Champlain TMDL
0.8 mg/l effluent concentration limit
2002 TMDL Limit
Dishwasher detergent law
(18.4)
Long-term trends in phosphorus loading to Lake Champlain from all sources
Pho
spho
rus
Load
(mt/y
r)
0
200
400
600
800
1000
1200
1400
Gag
ed F
low
(hm3 /y
r)
0
2000
4000
6000
8000
10000
12000
19911992
19931994
19951996
19971998
19992000
20012002
20032004
20052006
20072008
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.
0
2000
4000
6000
8000
10000
12000
14000
Federally-subsidized superphosphate (in tons) brought into Vermont for farmers to apply to fields.
Images from the Landscape Change Program
Deforestation and over-grazing in Vermont during the 19th century caused tremendous erosion of upland soils.
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!