clean and clear

wastewater

There are 60 wastewater treatment plants discharging phosphorus in the Vermont portion of the Lake Champlain Basin. These facilities include municipal and private industrial plants, and other facilities such as fish hatcheries. Untreated wastewater contains high concentrations of phosphorus, but much of the phosphorus in wastewater can be removed through advanced treatment processes.

Vermont has been making capital investments to upgrade wastewater treatment facilities for phosphorus removal for many years. Between 1979 and 2001, before the Lake Champlain Phosphorus TMDL was adopted, 30 municipal facilities in the Lake Champlain Basin were upgraded for phosphorus removal at a capital cost of $39 million.

State law limits the concentration of phosphorus in the effluent from larger facilities in the Lake Champlain and Lake Memphremagog basins to a monthly average of 0.8 milligrams per liter. In addition, the Lake Champlain Phosphorus TMDL established individual, annual mass loading limits (in metric tons per year) for phosphorus at each wastewater discharge in the basin. Compliance with the loading limits in the TMDL required the additional construction of phosphorus removal upgrades at five aerated lagoon type treatment plants. The state currently provides grants to municipalities for 100% of the capital cost of constructing needed phosphorus removal upgrades.

Vermont’s long-term program to reduce wastewater discharges of phosphorus to Lake Champlain represents a major success story. As a result of these investments, phosphorus loading to Lake Champlain from Vermont treatment plants has declined by 83% since 1991. During the 1970s, wastewater discharges made up nearly half of the total phosphorus load to Lake Champlain. Recent river monitoring data indicate that wastewater discharges are now less than 10% of the total load to the lake.