Axa Assurance Maroc - Insurer Innovation Award 2024
Spahr
1. GROWING PAINS
Uneasy co-existence: Lake
Champlain and the modern humans
R.Lana Spahr
2. Lake Champlain, briefly designated as one of America's
"Great Lakes" is certainly one of the largest and most
extensive freshwater lakes in the country. It spans geo-
political boundries, as well as ecosystems and watersheds,
120 miles wide, up to 12 miles wide and containing an
immense 6.8 quadrillion gallons of water.
3. Objective of Presentation
I intend to demonstrate how the Lake Champlain environment
is negatively affected by human-created nutrient over-load,
or eutrophication and why applied solutions have had only an
incremental effect. The Lake's regions,or segments, some
naturally eutrophic, have collectively become more so, with one
result manifestation as algal blooms and damaged ecology
resulting from this. While Phosphates are the general cause of
this phenomenon, it is not simply an obvious cause and effect
situation. The factors involved include increased population
and population density, greater reliance on intensive
agriculture, and a collective (over time) result of many human
activities. Combine eutrophication with the impact of exotic
species and you have a situation of over-all weakened
ecosystems.
4. Ecological Mechanisms
While Nitrogen adds to the process of Eutrophication, it is
considered a lesser limiting factor in freshwater bodies while
Phosphorus is the primary limiting factor in the growth of
primary producers such as algae. The Lake has several basin
regions, which are of varying depth, geologic characteristics, fed
by differing watersheds and sometimes separated by shallow
bars. Theses differing basins and bays have differing trophic
levels, varying from a clear oligotrophic environment, with low
natural algae growth and nutrients and high oxygen levels to a
turbid eutrophic environment, high nutrient levels and algae
growth and low oxygen levels.The naturally eutrophic segments
of Lake Champlain are usually bordered by extensive wetlands,
for example the South Lake, where decaying plants and feeding m
organisms cycle Phosphorus back into its shallow depths.
5. Ecological Mechanisms (Con't)
Eutrophication is a hazard because algae quickly increases its
population, and oxygen is suddenly scarce, and light
diminished. Algae increases the plankton, which temporarily
increases food for snails and fish. As these populations briefly
swell, this is unsustainable, and they soon die-off. The micro-
organisms involved in the decomposition use still more Oxygen,
and the balance is altered further.
In addition, some fish need a certain turgidity and sediment of
water to lay their eggs in and when the ecology is shifted, exotic
species who are adapted to this new less-oxygenated, lower
light environment might gain a foot hold.
6. Before analyzing the phosphorus run-off in the Lake, lets look
at the watersheds surrounding the Lake.
7. WATERSHED PHOSPHORUS
Phosphorous enters into lakes and rivers in many ways -
storm drains, as a by-product of waste-water treatment and
through various industries. These are 'point-sources' where you
can 'pin-point' the source. A large amount of it however, almost
80%, doesnt enter directly, but is agricultural run-off from
manure and fertilizers and development run-off (i.e. lawn
fertilizers, detergents that first filter thought watersheds. These
are non-point sources, diffuse and widespread. The horizontal
lines on the previous graphic show the measured phosphorus
and the target (ideal) phosphorus for each section of the Lake.
8. Intensive Agriculture and Phosphates
1. Phosphorus on regional farms was often federally subsidized, and it was enormously cheap use. Many
previously forested land was converted to farm to intensive corn and dairy farming. In Franklin County, NY
heavily fertilized corn planting rose from 7.000 in 1950 to 27,000 acres in 2002. Franklin county contains the St'
Lawrence watershed which drains into the Lake. (source: R. Holt- love live share website) Not only does this add
to the overall Phosphorus load, the loss of the forests in the watershed means less filtration.
2. In addition to the fertilized hay, alfalfa, and corn grown often for Dairy cattle often requires phosphorus. A dairy
cow's urine and manure contains 30 times a human's production of Phosphorus. Phosphorus run-off can be
reduced by applying manure when the ground isn't frozen, composting correctly, and adjusting animal's
feed to give them only the amount of Phosphorus that they need. Riparian buffer zones can help to filter
hosphorus, before a stream or creek.
and uptake the P
9.
10. Changes in population & Land Use
As 80% of lake Champlain's Phosphorus run-off is from non-
point sources, it is important to look at the surrounding area.
The lake Champlain Basin program (LCBP) has fouund an
increase in area population of 25% from 1970, and 6.1% from
1990. While these might not be huge numbers, consider the
map in the previous slide- certain areas have doubled their
population (200% or more). It is interesting - i found that
Phosphorus levels didn't correspond with cities and towns.
Overall, the trend has been forested land has become farmed,
and farmed land is being developed.
Consider that 1200 out of 1900 of Vermonts farms are in the
Lake Champlain watershed! (Source: vermontagriculture.com)
11.
12. Analysis of Phosphorus Levels
Although the previous graphic seperated oligotrophic,
eutrophic, and mesotrophic (intermediate) basins of the Lake,
the overall trend was eutrophication. TMDL is the Total
Maximum Daily Load of Phosphorus that a waterway can
process, and the TMDL , differing for various regions and
ecosystems within the lake is marked by a red line. Most
sections of the Lake were close to that line or vastly exceeding
it.
13. Comparison of Land use and Phosphorus
I have found that the segments of th e Lake found in 2000 to
be impaired by the VA-NR DEC (Vermont Agency of natural
Reasources, Dept. of Conservation are the same areas that
experienced population growth, watershed contamination, and
high Phosphorus levels. For example, the watershed feeding the
Otter Creek segment had an area population growth of 50-
200% in different parts of it. This segment of the Lake
measured very high in Phosphorus in the 90s, as did its
watershed. Population growth by itself doesn't always indicate
a large increase in Watershed and Lake levels, as an increase in
people isn't an indicator for type of land use. However the
correlation of watershed and lake Phosphorus excess was
much closer.
14. Comparison of Land use and Phosphorus
(con't)
The six highest concentrations of watershed Phosphorus,
including the highest level of Missisquoi Bay, whose watershed
spans New york, vermont, and Canada, were all areas of the
Lake Champlain waters that the Vermont Department of
Conservation flagged as 'impaired waterways'. Although
population growth paid a large part into the Phosphorus
problem, the impairment and hazardous TMDLs of the
Watersheds was the greatest cause of the Phosphorous
problem.
15. Persistence and Continued Efforts
While there are dozen of non-government and government
organizations that are working to improve Lake Champlain for
all of its human and non-human inhabitants, efforts to fight
Eutrophication have been mixed. Phosphorus, to some degree
stays put- it does not combine to form a gas like Nitrogen or
Sulfur. On a farm, for example, the soil chemistry and ecology
can suffer from Eutrophication. the Phosphorus in the soil will
leach out eventually, sometimes for decades and this has been
found to be the case in the lake Champlain area (citation found
but lost). This makes improvements in agriculture and newer
BMPs (Best Management practices), hard to measure.
Of course, non-point sources are hard to regulate, as they
occurs over hundreds of acres, and across jurisdictions. In
conclusion, knowing exactly how to measure the progress is as
important as education and mitigation of the problem.