Effects of Utility Scale Solar Energy on Aquatic Ecosystems in the Southwest

 

by Melanie Paty

In a recent Environmental Management article, Grippo, Hayse, and O’Connor (2015) speculate on the potential detriments solar farm development imposes on temporary bodies of water and the wildlife that depend on them. The authors’ locational focus is the Southwestern United States, where there are more than 40 pending or approved solar development permits. Temporary bodies of water, either intermittent, “seasonally dry stream, especially during times of low rainfall or high heat,” or ephemeral, “defined as those that do not receive groundwater inputs and contain water only briefly and in direct response to precipitation,” play an important role in desert ecosystems: they connect the landscape, transport water and nutrients downstream, serve as the short-term habitat for animals with aquatic life stages and the reproductive site for various animals, and give rise to riparian corridors that provide a variety of benefits to local animal species. However, unlike permanent bodies of water, temporary water is not protected under the Clean Water Act, unless it is significantly connected to a permanent body of water. Thus, temporary bodies of water are often disturbed in construction or operation of solar farms; the three greatest concerns are disrupted flow, water contamination, and groundwater depletion. Water quality is jeopardized because in order to limit the amount of dust that accumulates on the mirrors and panels, solar farms use dust suppressants that contain chloride salts and brines. Limited data are available on the toxicity of these substances, but some have been shown to increase algal growth, reduce oxygen levels, and increase salt content to a point that is toxic for aquatic species. The authors recognize that it is impossible to go forward with solar plant construction without disturbing the temporary water bodies, so they suggest minimizing the impacts in a variety of ways, primarily through increased monitoring of detrimental effects. Some examples include: finding the sustainable groundwater yield, calculating the vulnerability of streams to erosion, and mapping groundwater-dependent communities at regional and site-specific levels.

While increase monitoring would be helpful, it would also be interesting to do a cost benefit analysis of the monitoring and avoidance measures, because, as the authors note, none of the threats have proven to produce population-level effects. While solar farms do have negative environmental impacts on the desert ecosystem, which is undervalued, the oil and gas industry has also had detrimental effects on many other ecosystems; thus, while it is important to ensure that solar farms are employing the most sustainable practices, it is also important to recognize that there are always tradeoffs, and clean energy offers much promise for a more sustainable future overall, despite some negative effects.

Grippo, M., Hayse, J., O’Connor, B. (2015). Solar Energy Development and Aquatic Ecosystems in the Southwestern United States: Potential Impacts, Mitigation, and Research Needs. Environmental Management (55) 244–256.

 

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