Mowing Vegetation as Mitigation: Trump Administration Practice Goes Unchallenged

The Trump administration is again touting the practice of mowing thousands of acres of desert vegetation as environmentally-responsible, despite a preponderance of evidence to the contrary.  The draft environmental review of the Yellow Pine Solar project in southern Nevada claims that vegetation mowing - as opposed to bulldozing - will yield positive outcomes that are highly doubtful.   This positive framing of the construction practice misleads the public and decisionmakers and ignores decades of scientific research regarding the impacts of mechanized disturbance on desert wildlands.  According to the draft environmental review:

"Mowing is becoming the standard on large site-type ROWs to prevent permanent impairment of public lands (as mandated by FLPMA) and in lieu of off-site mitigation...Mowing methods are designed to help preserve soils, biological soil crusts, soil seed banks, native perennial vegetation diversity and structure, and cacti and yucca species, and to resist weed invasions, dust, and erosion. " - Draft Environmental Impact Statement for the Yellow Pine Solar project in Nevada, page 2-12

The Yellow Pine Solar project would be built on nearly 5 square miles of desert wildlands between the Nopah and Spring Mountain ranges. 

Describing vegetation mowing as a replacement for "off-site mitigation" (or protecting habitat elsewhere) sets a dangerous precedent in policy, and also in messaging.  The construction practice will still result in extensive crushed vegetation, compacted soils, and a drastically undermined ecosystem.  Is it better than bulldozing? Yes, in the same way that getting shot in the leg is better than getting shot in the face.  It is much better to just avoid it, and install solar on already-disturbed lands and on rooftops.

The video below shows mowing of vegetation during construction of BrightSource Energy's hybrid natural gas/solar power tower facility in California. And this precedes additional disturbance caused by other vehicles used to dig trenches, clear access roads, and install posts and solar panels.

Before issuing the Yellow Pine Solar analysis, Trump's Interior Department in November issued the final environmental review for the 11 square mile Gemini Solar project, also in southern Nevada.  In that document, Interior dubiously claims that desert tortoises - listed as a threatened species and whose population continues to spiral downward - will be able to inhabit that solar site even after vegetation is mowed and soils are compacted by tractors.   Interior plans to reintroduce up to 183 desert tortoises to the Gemini Solar site once construction is complete.  The plan is clearly arbitrary and capricious because the same final environmental analysis also acknowledged that whether or not the reintroduction will succeed is "unknown."  

"This vegetation is expected to rebound within a few years of construction, based on evidence from other Mojave Desert solar facilities where vegetation was crushed and allowed to regrow.  General wildlife species that can fly over, fit through, climb over, or crawl or burrow under the security fencing are expected to continue to inhabit the solar facility, both during construction and O&M."   -Final Environmental Impact Statement for the Gemini Solar project, page 3-69

The bulk of scientific study indicates that mechanized disturbance of desert soils can have cascading impacts on vegetation and the animals that depend on that vegetation, including the desert tortoise.  Mowing vegetation across a solar site will require multiple passes by heavy equipment, in addition to the heavy equipment needed to construct access roads, dig trenches, and instal thousands of posts and solar panels.  These vehicle passes will not only crush vegetation, but also compact the soils.  Studies of off-highway vehicle (OHV) activity on Mojave Desert ecosystems conclude that:

“Important effects of OHV activities on soils and watershed function include soil compaction, diminished water infiltration, diminished presence and impaired function of soil stabilizers (biotic and abiotic crusts, desert pavement), and accelerated erosion rates. Compacted soil inhibits infiltration of precipitation. In turn, soil moisture available to vegetation is diminished, volumes and velocities of precipitation runoff increase, and soil erosion accelerates, leading to the formation of gullies and other surface changes. Additionally, soil compaction may inhibit root growth among plants, in which case organic matter, litter, soil fertility, and vegetative cover are diminished, further exacerbating the soil’s susceptibility to erosion.”  - Environmental Effects of Off-Highway Vehicles on Bureau of Land Management Lands: A Literature Synthesis, Annotated Bibliographies, Extensive Bibliographies, and Internet Resources, US Geological Survey

The Yellow Pine Solar project, if approved, will result in the removal of wildlands hosting a diverse array of plant and animal species. During surveys of the site, biologists observed dozens of desert tortoises and several burrowing owls.  Raptors were noted foraging over the site, to include golden eagle and red-tailed hawk.  Lesser nighthawk, loggerhead shrike, barn swallows, horned lark, and sagebrush sparrows were among the many other bird species observed.  Botanical surveys encountered instances of Fremont's phacelia, chicory, beavertail cactus, California poppy, wolfberry and desert almond, in addition to the abundance of Mojave yucca and creosote.   All of this will be cleared and crushed to make way for solar panels that, with the right policies in place, can be installed on already-disturbed lands or on rooftops.

If you wish to send public comments on this project to the BLM by the May 4 deadline, please visit this Basin & Range Watch info page.  At the bottom you will find suggestions on what to include you in your comments.  Comments can be e-mailed to:  blm_nv_sndo_yellowpine@blm.gov