Just as watersheds enable the human and natural worlds to function as they do, they are vulnerable to harmful effects resulting from activities in those worlds. Fire can ravage a watershed, as the 1947 fire on Mount Desert Island did many of the watersheds on the east side of the island. Hundred-year storms can fell trees over a wide area and produce flooding, the effects of which will last for years. Falling rocks can destroy sections of watershed trails that have been used for decades, as they recently did on the Precipice Trail. And wildlife moving into a watershed can spur managers to close trails, as has happened in Acadia National Park as the result of peregrine falcons, a species endangered in Maine, nesting in the vicinity.

Typically, watershed concerns focus on the issue of waterborne pollution. Two types are commonly identified: 1) site-specific pollution events stemming from an identifiable source such as an outfall pipe or spill/leak site (point source pollution), and 2) diffuse pollution events occurring over a broad area such as phosphorus (a plant nutrient promoting algal blooms and subsequent oxygen depletion) or chemical runoff from a built or cleared area (nonpoint source pollution). A partial list of sources of waterborne contamination includes:

• leaking gasoline storage tanks
• oil spills, the dumping of crankcase oil
• leaked dry cleaning solvents
• improperly constructed septic systems
• chemical leakage from landfills
• malfunctioning septic systems
• industrial waste and storage sites
• agricultural chemicals and nutrients
• pathogenic organisms
  • bacteria (e.g., fecal coliform, fecal streptoccocci)
  • protozoa (e.g., giardia)
  • certain viruses and fungi
• organic material
  • biochemical oxygen demand (BOD)
  • dissolved oxygen
• nutrients
  • nitrogen (nitrate, nitrite, ammonia)
  • phosphorus (dissolved ions and inorganic molecules)
• dissolved solids
  • specific ions (e.g., sodium, potassium, calcium, magnesium)
  • general measures (total dissolved solids (TDS), conductivity)
• sediments
  • suspended sediment (measured as concentration of turbidity)
  • stream bottom sedimentation
• toxics
  • metals (e.g., cadmium, lead, mercury)
  • pesticides (insecticides, herbicides, fungicides

Of particular concern to Acadia and Mount Desert Island are:

• lawn fertilizers
• poorly maintained camp/gravel roads
• winter road salt use
• malfuncioning septic systems
• backyard trash piles
• increased rate of construction/development

Significant watershed contamination can also be traced to deposition of airborne chemicals emitted by vehicles, industrial plants, incinerators, and similar sources. Additional watershed threats include:

• forest fragmentation
• stream channel modification
• upland habitat degradation or loss
• streamflow diversion
• wetland degradation or loss
• thermal pollution
• combined sewer overflow
• loss of riparian buffers and habitat areas
• roadway runoff
• insect defoliation

Increasingly, researchers are reporting indications of climate instability or change on a global scale. Any long-term trends in the regional climate would affect vegetation and wildlife in Mount Desert Island watersheds in a variety of ways beneficial to some and unfavorable to others. Acadia may see red spruce forests (at the southern end of their current range) move north, and red oak hardwood forests (at the northern edge of their current range) move up from the south. If the climate warms by only a degree or two, an increasing amount of polar ice will melt, sea level will rise, and the island coastline will shrink.

Learn more about Acadia's water resource program.