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In 2002 the Environmental Protection Agency (EPA) approved
a plan submitted by Vermont and New York to reduce the amount of phosphorous
in Lake Champlain called the Lake Champlain Phosphorous TMDL (Total
Maximum Daily Load).
Essentially a TMDL (Total Maximum Daily Load)
is the maximum amount (load) of a single pollutant from all contributing
sources that a water body can receive and still meet water quality standards.
A TMDL is required for Lake Champlain because phosphorus concentrations
in many segments of the lake are higher than the levels allowed.
Phosphorous is a naturally occurring nutrient essential for plant growth.
It is found in all living and once living things including leaves, lawn
clippings, and animal wastes. It is also common in fertilizers and automatic
dishwashing detergents. Too much phosphorous in water causes algae blooms
that can be a health hazard for swimmers. Algae blooms block sunlight
and prevent oxygen-producing underwater plants from growing. When the
algae dies and decays, it uses up oxygen leaving little for fish.
About 10% of the phosphorus in the Lake comes from wastewater treatment
and industrial discharges (point sources). About 90% of the phosphorus
comes from runoff from roads and developed areas, and from lawns, farmlands,
and other rural areas (nonpoint sources). Of these nonpoint sources about
56% is from agricultural land, 7% is from forested land and 37% is from
urban and other developed land.
That 37% of phosphorous pollution from “urban and other developed land”
is generated from activities such as washing cars on roads and driveways,
not cleaning up pet waste, using automatic dishwashing detergents that
contain phosphorous, and over-fertilizing lawns and gardens.
In 2006, as required by the TMDL, the Vermont Legislature passed a bill
requiring the State to develop a campaign to reduce phosphorous in the
Lake by discouraging the use of phosphorous fertilizers on YOUR lawn.
If you’ve never heard of this before....
We’ve got a lot of work to do!
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Green Lawns, Not Green Waters
It’s possible to have an attractive lawn while keeping
phosphorous fertilizer out of stormwater runoff. The following steps will
help you keep your soil and grass healthy while still protecting our waters.
Fertilize Only as Needed: If a soil test confirms a need for extra
nutrients, apply organic fertilizer at appropriate times of year. If a
soil test is not taken and you want to apply fertilizer, assume that soils
have enough phosphorous and apply a phosphorous-free fertilizer. (For
information about soil testing, visit www.lcbp.org/garden.htm). Avoid
or reduce summer applications. The best once-a-year application is in
late summer or early fall. Use a drop spreader if possible and don’t fertilize
before a rain. Look for the Middle Number: A string of three numbers on
a fertilizer bag shows its analysis—the middle number being phosphate
(phosphorous) content. A “zero in the middle” means phosphorous free fertilizer.
Water: In early morning, when there is less than 1 inch a week
of rain during the growing season.
Plant Grass Seed: That includes a mixture of grasses that do well
in your setting (soil, light, activity). Add or rely on a legume (such
as common white clover) among the grass to add nitrogen. Apply grass seed
to existing lawns in fall and spring to out compete weeds.
Aerate: Heavily compacted lawns once a year in early fall to encourage
infiltration rather than runoff.
Mow: To maintain a height of 3 to 4 inches. Remove no more than
1/3 of the grass blade and leave clippings on lawn.
Weed: By hand when possible. Keep soils and plants healthy to out
compete weeds and avoid pests. Use an integrated pest management plan
(call the UVM Master Gardener Help Line 800-639-2230 for more information).
Lawn care information provided by Karen Bates, DEC; Sid Bosworth, UVM;
and Metro WaterShed Partners
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