The Lake Champlain Basin Program, created by the Lake Champlain Special Designation Act of 1990 to coordinate the implementation of the Lake Champlain management plan, has released its 2012 Lake Champlain “State of the Lake Report”. The report, which is issued every 3-4 years, concludes that the water should be treated before drinking or bathing, most of the lake is safe to swim in most of the time, and some fish may be eaten, if “consumed responsibly” according to fish consumption health advisories.
Phosphorus levels and the potential threat of toxic algae blooms remain elevated. Mercury and PCB contamination in fish is declining, but new chemical threats are on the rise. Invasive species remain a serious problem, especially to game fish and native mussels, but biodiversity projects such as fish ladders, and wetland and riparian habitat restoration or enhancement has made progress in protecting sensitive ecosystems in some areas.
“We use scientific data to determine what kind of progress is being made on the management of Lake Champlain water quality and habitat health,” Bill Howland, LCBP Program Manager, said in a statement issued to the press today. “Again, in 2012, we share both good and not so good news, depending on which issue and which lake segment is being discussed. Certainly the Lake is not meeting phosphorus concentration targets, but each jurisdiction remains diligent and active in their efforts to decrease loads.”
Here are some of the big trends being reported, lifted from the report:
Don’t Drink or Bathe With The Water Unless Treated
The risk continues for exposure to coliform bacteria following storms, and public health agencies around the Lake recommend that all water collected directly from the Lake be treated at a minimum with an ultraviolet light or chlorination system prior to use (for both drinking and bathing).
Swim With Caution to Avoid E. Coli and Algea Blooms
Of the 35 public beaches on Lake Champlain that were evaluated for this report, closures due to coliform bacteria totaled 66 temporary closures and three extended closures (more than one week), between 2008 and 2011. Beach closures due to cyanobacteria blooms have been even less frequent with eight closures in the same time period. Public beaches in Missisquoi Bay were closed for significant periods of time in 2008 and 2011 due to cyanobacteria (blue-green algae) blooms, the risk of which continues to be elevated following 2011 flooding. Beaches in Burlington and Shelburne, VT have at least one closure annually due to coliform bacteria or cyanobacteria.
Eating Fish Possible, Within Limits
Data collected in 2011 for sportfish in Lake Champlain reveal substantial declines in mercury levels in the tissue of three of the five most common sportfish. Average sized lake trout are approaching the US EPA criterion for consumption. Fish mercury levels are expected to improve with newly issued US EPA regulations on mercury emissions from coal-fired power plants. While other fish advisories remain in effect, New York State ended more strict consumption advisories in Cumberland Bay near Plattsburgh after following significant declines in PCB levels in fish tissue.
Phosphorus levels in most areas have been stable or increasing slightly since 2007. In 2010, the average in-lake phosphorus concentrations exceeded established targets at nine of the thirteen lake segments. The historic floods of 2011 caused a spike in phosphorus concentrations in many parts of the Lake to the highest levels observed since 1990.
New Generation Contaminants Present
A 2006 study by the USGS found 70 different “new generation contaminants” present in low levels in Lake Champlain Basin waterways. These products include fire retardants, plasticizers, pesticides, fragrances, stimulants, and detergents associated with potential human health and ecosystem quality risks. During the 2008 lampricide treatment of the Missisquoi River, traces of the lampricide were detected at a Québec water treatment facility. Although concentrations were still below US EPA thresholds, this was cause for concern.
Biodiversity Declining, But Habitats Improving
Riparian habitat remains threatened, although progress has been made to reverse these trends. Since 1995 4,000 acres of wetlands and approximately 300 miles of riparian habitat have been restored or enhanced. 30,000 trees have annually been planted as buffers along stream banks in the Basin. The zebra mussel invasion in Lake Champlain has led to serious declines in native mussel populations. In Vermont, eight of the Basin’s fourteen native mussel species are threatened or endangered, including the black sandshell, pocketbook, and pink heelsplitter mussels.
Invasive Species A Significant Problem
As of 2011, Lake Champlain is home to 49 known aquatic non-native species, many of which are invasive, but the rate of invasions has been reduced since 2000. Water chestnut remains a major problem in Lake Champlain, but notable progress has been made in in controlling this specie from Benson VT north. Scientists have documented recent declines in zooplankton populations. There is no effective means for control of white perch, zebra mussels, and alewife, among the most aggressive invasive species. White perch, first documented in the Lake in 1984, is now the dominant fish species found in Missisquoi Bay. Zebra mussels have heavily colonized the shallow-waters of the Main Lake, South Lake and parts of the Northeast Arm. In 2008, a widespread alewife die-off occurred in the Lake, confirming that a large population had become established. The most recent invasive is Variable-leaf watermilfoil which was found in the US section of Missisquoi Bay in September 2009; another infestation of more than 80 acres was discovered in 2011 on the New York side of South Bay.
Fishing Opportunities Stable, Some Improvements
Smallmouth and largemouth bass catch rates and the size of fish at tournament weigh-ins have increased over the past four to five years. Lake trout stocked by New York and Vermont grow well and reproduce, but few survive the first year of life. Stocking, habitat restoration, and improving fish passage for landlocked Atlantic salmon have produced record catch rates at fish passage ladders on the Boquet and Winooski Rivers. Strong spawning runs in 2010 and 2011 broke annual catch records for both rivers. In 2011, 189 salmon were collected in the fish lift at the Winooski One hydroelectric facility, exceeding all previous records since the lift began operating in 1993. Muskie, Lake sturgeon, and whitefish remain at artificially low levels, although appear to be mostly stable. Sea lamprey wounding on lake trout and salmon has dropped to the lowest rates since monitoring began in 1985.
Climate Changes Taking place
Average August surface water temperatures have increased in Lake Champlain as much as 6.8°F (3.8°C) since monitoring began in 1964. Additionally, the average air temperature in the region increased by 2.2°F (1.2°C) from 1976 to 2005. This increase corresponds with data throughout the Northeastern United States and Great Lakes. Precipitation also is showing an upward trend; the average annual precipitation over the past 40 years has increased 3 inches as compared to the prior 80 years. Lake Champlain has frozen-over less frequently in the last 50 years than in the prior 130 years and the data show that this trend might be accelerating.
2011 Flooding Heavily Impacted Lake
Preliminary analyses indicate that nutrient delivery to the Lake from most tributaries was well above the 20-year average, and in-lake phosphorus concentrations were above average as well. Management agencies around the Basin are developing flood resiliency plans to mitigate impacts of flood events in the future.
The full report can be found online [pdf].