How vegetation loss makes lakes and rivers more vulnerable to algae growth

Natural shoreline retained

Minimal development scenario.
minimal impact development allows the natural background and nutrient flow to meet the needs for aquatic life, resulting in clean water and habitat that supports healthy fish and wildlife

In this scenario, the lake home is set back from the water and most of the existing natural vegetation between the home and the lake and along the shoreline is left intact (Figure 1). This vegetation holds soil in place and slows down nutrient-laden runoff, increasing infiltration and decreasing the amount of nutrients flowing into the lake. In this more natural condition, nutrient flow is in equilibrium with the needs of aquatic life resulting in clean water and habitat that supports healthy fish and wildlife. 

 

Contemporary shoreline development

 
Replay
minimal impact development allows the natural background and nutrient flow to meet the needs for aquatic life, resulting in clean water and habitat that supports healthy fish and wildlife

In contrast, suburban-style or lawn to lake shoreland development features little to no natural vegetation, particularly along the shoreline. Natural vegetation between the home and water is replaced with lawn and hard surfaces such as patios, BBQ pits, boulder walls, and stairways (Figure 2). Under historical average rain fall, these ‘lawn to lake’ developments contribute 7 to 9 times more phosphorus to surface waters than more naturally vegetated shorelines. The average ‘lawn to lake’ lot contributes 0.2 pounds of phosphorus (through runoff) per summer compared to 0.03 pounds for a lot with a naturally vegetated shoreline . This increase in phosphorous results in 100 pounds of algae compared to just 15 pounds under natural conditions. Over time, as more shoreland lots develop this way, more lakes will experience algal blooms and loss of clean water.

 

Contemporary shoreline development + climate trends

Replay
Increasing rain intensity causing even more nutrient flow and sedimentation and with warming waters resulting in excess algae and loss of fish and wildlife

Continued contemporary shoreland development along with more intense rain events and warming waters are accelerating the growth of algae and aquatic plants and loss of clean water. Unless the flow of nutrients to our lakes and rivers are reduced, we face:

 

  • Growing health and safety concerns for our families and pets due to more frequent and long-lasting algal blooms, some toxic.
  • Reduced swimming and other in-water activities due to increases in aquatic plants and algae.
  • Loss of fish and wildlife species we associate with natural areas, including loons.
  • Loss of recreational tourism businesses due to loss of fisheries and/or declining water quality.
  • Decline in shoreline property values and tax base due to declining water quality. 

1. Radomski, P. J., and K. Van Assche. 2014. Lakeshore Living: Designing Lake Places and Communities in the Footprints of Environmental Writers. Michigan State University Press, East Lansing.

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