There is little question that any current discussion about the feeder streams is focused upon erosion, sedimentation and aggrading deltas where the streams enter the lake. Most available evidence indicates that these issues have become more serious since the mid-1990's. As Susan Warren noted in a 1998 letter, "These large sediment deltas are not natural and may be serving as an early warning sign that the lake is receiving significant pollutant inputs."
The pollution is the result of nutrient loading in the sedimentation, particularly phosphorus loading. Even small increases in phosphorus loads can cause large algal blooms. (See Appendix 13 for a detailed explanation of the link between sediment and nutrient loading.).
That said, erosion is part of a natural process. All one needs to do is look at old pictures of the "Watson Sand Bar” to realize that sedimentation and aggrading deltas are not a new phenomenon. Over the next millennia, Caspian Lake will continue to fill in. During our watch, the best we can do is engage in practices which do not accelerate the natural process.
The studies which are available suggest that there are three principal contributors to the recent increases of sedimentation: (1) runoff from the roads and driveways which surround the lake; (2) landowner practices which increase and concentrate runoff speed and volume; (3) new development, which inevitably taxes the capacity of the watershed to buffer storm runoff.
While some would like to isolate one single cause, it will require diverse and proactive efforts to address the problem.
Greensboro residents have noted that maintenance on the dirt roads around the lake has improved dramatically in recent years, and for that they are grateful. More gravel and more frequent grading have improved travel and saved wear and tear on vehicles. However, every ton of dirt and gravel used to maintain and improve the roads inevitably gets washed downhill toward the lake. Now, more than ever, culverts and drainage ditches will accelerate runoff and erosion unless properly installed and maintained in conformance with best practices. According to Jim Ryan there are several culverts and ditches which are likely candidates for either repair or replacement. (See Appendix 3)
There are numerous resources available which identify best practices for maintaining back roads. One of the most useful is the Better Back Roads Pocket Guide; a link is provided in Appendix 12.
Several of the more recent repairs to west Lake Shore Road and North Shore Road have been part of Better Back Roads projects and have been designed to minimize runoff.
Riparian property owners are also contributing to the sedimentation. Riparian buffers have been compromised. Aggressive logging has taken place too close to the feeder streams. Field drains are channeling water into the riparian zones. Poorly designed or maintained domestic drainage systems and driveways are doing the same thing.
During the committee's inspection tour, Jim Ryan noted four separate instances where landowner oversight was contributing to erosion. Taken separately, landowner oversights may seem inconsequential. However, the cumulative impact can be significant.
Finally, development itself is part of the problem, because it removes land, sometimes Class Three wetlands, from the natural buffering process, which in turn puts more pressure on the feeder streams. In her 1999 study, Lori Barg expressed serious concern about the degradation of the Class Three wetlands surrounding the lake.
There are existing state resources available to help riparian landowners who wish to minimize erosion and sedimentation. Interested landowners should contact either Amy Picotte (Amy Picotte@state.vt.us) or Justin Kenney (Justin.Kenney@state.vt.us). Both work for ANR in the Watershed Division.