January 8, 2016 Dear Committee to Save the Wiltsey Oaks: Thank you for calling my attention to the proposal (Marion Co. Case No 15-035) to construct a commercial-scale solar installation on 12 acres of the 44-acre property bordered by Wiltsey St. SE on the north, and Coates Drive SE. After viewing the site, I have two major concerns that the conditional use criteria in MCC 17.137.060(A) have not been sufficiently evaluated. Specifically those concerns relate to the requirement that: “The use will not have a significant adverse impact on watersheds, groundwater, fish and wildlife habitat, soil and slope stability, air and water quality. ” with emphasis on the terms highlighted in bold: (1) groundwater and (2) wildlife habitat. A further concern is whether the native cultural/archaeological value of the site has been adequately taken into account. I'll elaborate on these concerns in order, noting also that these comments are provided pro bono. Groundwater impacts The South Salem Hills have been delineated as a Groundwater Restricted Area with “limited availability,” by the Oregon Water Resources Department. A particular concern in this area is the long-term decline in water levels for wells in basalt. I have not made a detailed analysis of this particular site. However based on general principles of hydrogeology, this type of upland site should be expected to function as a location where rainwater infiltrates to recharge bedrock aquifers. Given that large boulders 1 m or more in size are visible on the site, and are moss-covered (indicating that they have been present and undisturbed for many years), this likely indicates that the bedrock is close to the surface. Considering the state-recognized sensitivity of bedrock aquifers in this area, the significance of this site as a groundwater recharge area, and the potential impacts of the solar installation on groundwater recharge should be evaluated. In rough numbers, a 12-acre site in the Salem area receives about 40 acre-feet of precipitation per year, or about 13 million gallons of fresh water – enough to serve the needs of at least 90 households. Presently the site proposed for this solar installation is covered by stony Nekia and Witzel soils. The Clearwater Hardrock Consulting · 38566 Hwy 99W · Corvallis, Oregon 97330-9320 USA · +1 541 745-5821 site appears to have been used mainly as pasture, which implies minimal compaction. The present grassy vegetation is likely to promote infiltration rather than runoff. I note that the applicants have included plans for a sedimentation basin in their plans, which indicates an expectation of increased runoff, and correspondingly decreased groundwater recharge. Increased runoff and decreased infiltration are indeed what should be expected from a solar development, due to re-grading and compaction of natural soils by heavy equipment during construction of the panels, plus the need for hardened surfaces to allow access for routine maintenance. This consequence of “site hardening” is a well-known phenomenon for standard commercial solar installations, so it should be expected in the absence of very detailed disclosures by the applicants, of measures to avoid such effects. Clearwater Hardrock Consulting · 38566 Hwy 99W · Corvallis, Oregon 97330-9320 USA · +1 541 745-5821 Wildlife impacts The most significant features of this site as wildlife habitat are (1) the presence of numerous native Oregon white oaks more than a century in age – some of them likely at least 150 years old -- that show growth characteristics typical of an oak savanna environment, (2) the continuing oak savanna structure of the habitat, (3) documented presence of at least three bird species highly correlated to savanna habitat that are Oregon Species of Special Concern (Slender-billed Nuthatch, Western Bluebird, and Chipping Sparrow), plus a few local sightings of another Species of Special Concern, Acorn Woodpecker, and (4) highly suitable habitat for another Species of Special Concern, Oregon Vesper Sparrow, which could have easily been missed by the limited monitoring to date. Some of the oaks on this site that would be removed to make way for the proposed solar installation are more than four feet in diameter at breast height (dbh), and many appear (at least from a distance) to be at least 2 ft dbh (see included photo). It takes at least 100 years for oaks to reach this size, so any “restoration” of the site following clearing for solar panels would be a multi-generation endeavor. Even more significant is that most of the oaks show evidence of growth in a savanna setting, where the trees were widely spaced, so there is good development of lateral branches which are important for many wildlife species associated with oak savanna habitat. Based on an analysis using Google-Earth images of the site, the current canopy cover by oaks is approximately 2.8 acres over the area of 21.2 acres for the main area in which the solar panels would be sited. This amounts to roughly a 13% oak canopy cover, which is well within the technical classification for oak savanna (up to 25% canopy cover). During a brief visit to an adjoining property on December 30, 2015, I detected at least three Slender-billed (White-breasted) Nuthatches that were making use of these oaks. This was not in the expected season for Chipping Sparrows to be present, but the habitat appeared to be suitable for nesting, based on my experience in surveying similar habitats. I also noted the presence of oak mistletoe which is important as a winter food source for Western Bluebirds. Acorn Woodpeckers have been noted by neighbors of the site. The combination of thin, rocky soils, southward/western aspect slopes, and savanna habitat structure also appears to be highly suitable for another Oregon Species of Concern, Oregon Vesper Sparrow during nesting season. This species would be difficult to detect without a focused survey, so it should be considered to be possibly present. Most of these species would be compatible with ongoing use of this site as grazing land, under the current Special Agricultural zoning. In particular, recent research by the American Bird Conservancy indicates that Oregon Vesper Sparrows will utilize cattle- or sheep-grazed oak savannas at densities up to one pair per 2 acres, under a light-to-moderate grazing regime. Clearwater Hardrock Consulting · 38566 Hwy 99W · Corvallis, Oregon 97330-9320 USA · +1 541 745-5821 Native cultural impacts As a rocky, hilltop site not conducive to plowing, it seems likely that this site has seen minimal disturbance since European-American settlement in the 1850s. An archaeological survey and assessment is therefore called for. Yours sincerely, Joel E. Geier, Ph.D., Hydrogeology Instructor, Oregon State University Master Naturalist Program, 2013-2015. Audubon Society of Corvallis field notes compiler, 1999-2006 & 2015 Willamette Basin field notes compiler, Oregon Field Ornithologists, 2000-2006 Contractor for Willamette Valley grassland/savanna/oak woodland bird research, 2007-2015. Owner, Clearwater Hardrock Consulting, specializing in groundwater flow and solute transport in fractured bedrock, 1993-2016. Clearwater Hardrock Consulting · 38566 Hwy 99W · Corvallis, Oregon 97330-9320 USA · +1 541 745-5821