A review of the essay
Essay Title : The environmental effects of damming rivers and of removing dams
Examiner: Dr Crile Doscher
Environmental Management and Design Division
Lincoln University
This essay is an excellent review of the often unappreciated ecological effects of dams and dam removal. In a country like New Zealand, where electricity from hydropower hovers between 65-85% of the country's total generation, dambuilding is second nature. As the author points out, many other countries have a similar disposition. When compared to other sources of electricity, hydropower is often pointed to as one of the "cleanest" and least harmful to the environment. This essay points out some of the falacies behind these beliefs by making the most of available literature, personal communication, and grey literature. It is clear that much effort has gone into the essay and its arguments are clear and balanced. My dictionary (Collins English Dictionary, 1998) defines essay as, "a short literary composition dealing with a subject analytically or speculatively." This has certainly been done.
If there is any criticism of the essay it would relate to scope. While the title refers to "environmental effects", the essay focuses more on the ecological impacts, particularly, but not limited to, the effects on fish species. This is backed up by the presence of fish images (which seem to multiply!) at the end of some sections. It is difficult to draw a boundary around a system when taking a more holistic view. This is particularly true with the systems considered here (rivers and their ecosystems) where, as the author points out, negative impacts tend to cascade throughout the system. Nonetheless, there are a few sections which seem to stand out as they depart from what seems to be a strong theme of the essay: dam effects on ecological communities. These sections are subsidence and landslides, greenhouse gases, water losses, and restored river flows. This is not to imply that these are unimportant--quite the opposite in some cases--but in reading through them I found myself asking: "But where are the fish?". Also, table of content page numbers should line up evenly.
At the heart of the issue of dam removal lie society's values. Which is more valuable to most people? A sound riverine ecosystem or the resources made possible by damming the river. This is a question for society and not for science. If society decides that restoring river runs and the ecological communities within them to a more "natural state" is desireable, then dam removal offers a viable method. The author is correct to point out that for it to be seriously considered, there must be a more concerted effort at documenting the true effects of dam removal. This essay provides an underpinning for those efforts to begin. I intend to have future students of mine who are interested in either the construction or removal of dams read this essay as part of their literature review as it provides a broad overview of the positives and negatives associated with dams and their removal.
Dr Crile Doscher
Environmental Management and Design Division.
Lincoln University