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<br />Soil Investigations for Data Collection in the Delta <br />Initial Study/Proposed Mitigated Negative Declaration 113 <br />Implementation of Mitigation Measures MM BIO-1b, MM BIO-12, MM BIO-18, <br />and MM BIO-19 would reduce potential impacts to Boggs Lake hedge-hyssop to: <br />Less than Significant with Mitigation Incorporated. <br />Diablo helianthella (Helianthella castanea) <br />Diablo helianthella has a CRPR of 1B.2 but is not listed under FESA or CESA. <br />This species is a perennial herb in the sunflower family, and it blooms from <br />March to June (CNPS 2019). It is endemic to California, and its current range <br />includes the northern Central Coast and northern San Francisco Bay Area <br />(CNPS 2019, Jepson Flora Project 2019). It is presumed extirpated from Marin <br />and San Francisco counties. It typically grows in broadleafed upland forest, <br />chaparral, cismontane woodland, coastal scrub, riparian woodland, and valley <br />and foothill grassland (CNPS 2019). The microhabitat for Diablo helianthella <br />includes interfaces between chaparral and oak woodland in rocky, azonal soils, <br />often in partial shade (CDFW 2019). Threats to this species include <br />urbanization, grazing, fire suppression, road maintenance, recreational activities, <br />and non-native plants (CNPS 2019). This species has low potential to occur <br />within the Study Area based on the presence of marginally suitable habitat. <br />Implementation of Mitigation Measures MM BIO-1b, MM BIO-12, MM BIO-18, <br />and MM BIO-19 would reduce potential impacts to Diablo helianthella to: Less <br />than Significant with Mitigation Incorporated. <br />Brewer’s western flax (Hesperolinon breweri) <br />Brewer’s western flax has a CRPR of 1B.2 but is not listed under FESA or <br />CESA. This species is an annual herb in the flax family, and it blooms from May <br />to July (CNPS 2019). It is endemic to California, and its current range includes <br />the southern Inner North Coast Ranges, northwestern San Joaquin Valley, and <br />northeastern San Francisco Bay Area (CNPS 2019, Jepson Flora Project <br />2019). It typically grows in chaparral, cismontane woodland, and valley and <br />foothill grassland (CNPS 2019). The microhabitat for Brewer’s western flax <br />includes rocky serpentine soil within chaparral and grasslands (CDFW <br />2019). Threats to this species include development and the construction of Los <br />Vaqueros Reservoir (CNPS 2019). This species has low potential to occur within <br />the Study Area based on the presence of marginally suitable habitat so potential <br />impacts would be less than significant. <br />Implementation of Mitigation Measures MM BIO-1b, MM BIO-18, and MM BIO-19 <br />would further avoid, minimize and/or reduce the potential for impacts to Brewer’s <br />western flax. <br />Hogwallow starfish (Hesperevax caulescens) <br />Hogwallow starfish has a CRPR of 4.2 but is not listed under FESA or CESA. <br />This species is an annual herb in the sunflower family, and it blooms from March <br />to June (CNPS 2019). It is endemic to California, and its current range includes