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Soil Investigations for Data Collection in the Delta Initial Study/Proposed Mitigated Negative Declaration 78 to suitable habitat and would reduce potential impacts to longhorn fairy shrimp to: Less than Significant with Mitigation Incorporated. Vernal pool fairy shrimp (Branchinecta lynchi) Vernal pool fairy shrimp is listed as Threatened under FESA but is not listed under CESA. It has a NatureServe ranking of G3S3 and is included on CDFW’s Special Animals List. This species is a 0.12 to 1.5-inch short-lived aquatic crustacean found in ephemeral freshwater habitats. The current range in California includes the Central Valley, Coast Ranges, and disjunct locations in Riverside County. Vernal pool fairy shrimp are found in a variety of vernal pool habitat types, ranging from small, clear sandstone pools to large turbid, alkaline pools. It is most frequently found in pools measuring less than 0.05 acres but has been found in pools exceeding 25 acres. Like other fairy shrimp, vernal pool fairy shrimp hatch from desiccated cysts that remain in the soil until the first winter rains and complete their lifecycle by early summer. Cysts are shed by mated females and remain in the soil until the following winter. Individuals hatch in water temperatures of 50 degrees Fahrenheit or lower and reach maturity approximately 40 days later depending on temperature (USFWS 2007c). The upper temperature tolerance for this species is approximately 75 degrees Fahrenheit (Erickson and Belk 1999). Threats to this species include habitat loss and fragmentation due to urbanization, agricultural conversion, and mining. Vernal pool fairy shrimp has moderate potential to occur within the Study Area based on the presence of suitable habitat. Implementation of Mitigation Measures MM BIO-1 and MM BIO-12 would avoid and minimize adverse impacts to suitable habitat and would reduce potential impacts to vernal pool fairy shrimp to: Less than Significant with Mitigation Incorporated. Midvalley fairy shrimp (Branchinecta mesovallensis) Midvalley fairy shrimp has a NatureServe ranking of G2S2S3 and is included on CDFW’s Special Animals List but is not listed under FESA or CESA. This species is a 7 to 20 mm short-lived aquatic crustacean found in ephemeral freshwater habitats. It is endemic to California, and its known range is limited to the Central Valley. Midvalley fairy shrimp are found in vernal pools; primarily small, short-lived pools and grass-bottomed swales that are less than 10 cm in depth. This species has been found in relatively alkaline pools, but its tolerance range for variations in water chemistry are not well known. Like other fairy shrimp, this species hatch from cysts that remain in the soil until the first winter rains; however, they mature comparatively quickly, in as little as 8 days (CDFW 2019c). This species is unusually tolerant of warm water temperatures of at least 90 degrees Fahrenheit and potentially higher, which helps them survive when the water in their typically small, shallow pools heats up (Erickson and Belk 1999). Midvalley fairy shrimp has moderate potential to occur within the Study Area based on the presence of suitable habitat. Implementation of Mitigation