5.10 Biological Resources

5.10 BIOLOGICAL RESOURCES Introduction This section addresses impacts to biological resources resulting from implementation of the Equal- Weight Project Alternatives. Biological resources present in the Study area include row crops and orchards, riparian resources along creeks, aquatic resources, and developed areas. Potential impacts to these resources were assessed by HT Harvey and Associates in April 2009 and previous studies. The biological resources study prepared for the General Plan expansion areas is provided in its entirety as Appendix 5.10 Biological Resources. Setting Regional Setting The Study Area is located in western Stanislaus County. The climate of the San Joaquin Valley in Stanislaus County is characterized by hot, dry summers and cool, moist winters with frequent heavy fog. Weather patterns in the valley result from the presence of the Coast Range to the west and the Sierra Nevada Mountains to the east. Overall, the Coast Range produces a rain shadow effect, with the majority of moisture falling on the coastal side of the mountains. During winter months, however, the offshore high pressure areas move further south on the coast, allowing the San Joaquin Valley to receive the majority (90%) of its annual precipitation. The average annual precipitation in Patterson ranges from 10 inches to 12 inches (USDA 2009). Temperatures range from an average high of 96°F and low of 63°F in the summer, to an average high of 54°F and low of 37°F in the winter (National Weather Service 2009). Local Setting According to the Natural Resource Conservation Service, the soils underlying the Study Area are well drained to moderately well drained, except for the hillsides of the Diablo Range foothills west of Interstate 5. A summary of the soil types present on the Study Area is provided in Table 5.10-1 below. CITY of PATTERSON ~ General Plan EIR 5.10-1 5.10 BIOLOGICAL RESOURCES Table 5.10-1: Soil Types In The Study Area Percent of Soil Type Acres Study Area Capay Clay 1,970 15.43 Capay Clay wet 1,359 10.64 Capay Clay, loamy substratum 271 2.12 Capay Clay, 0- 2% slope, rarely flooded 805 6.30 El Soylyo silty clay loam 293 2.29 Vernalis-Zacharias complex, 0-2% slopes 304 2.38 Vernalis loam, 0 - 2% slope 204 1.60 Vernalis clay loam, wet 12 0.09 Vernalis clay loam, 0 - 2% slope 794 6.22 Vernalis Zacharias complex, 0-2% rarely 387 3.03 flooded Vernalis loam, rarely flooded 1,173 9.19 Stomar clay loam 1,095 8.58 Zacharias clay loam, 0-2% slope 470 3.68 Zacharias gravelly clay loam 327 2.56 Zacharias gravelly clay loam 2-5% slope 194 1.52 Zacharias clay loam, 2 - 5% slope 278 2.18 Zacharias clay loam, 0 - 2% slopes rarely 404 3.16 flooded Zacharias gravelly clay loam, rarely flooded, 499 3.91 0-2% Cortina gravelly sandy loam 283 2.22 Calla-Carbona complex 419 3.28 Elsalado loam 240 1.88 Elsalado loam, rarely flooded 389 3.05 Elsalado loam, 0-2% slopes 292 2.29 Wisflat-Arburura-San Timoteo complex, 20- 306 2.40 50% slopes Total: 12,768 100.00 CITY of PATTERSON ~ General Plan EIR 5.10-2 5.10 BIOLOGICAL RESOURCES Plant Communities and Habitats within the Study Area Eleven habitats occur on the Study Area: California annual grassland, irrigated crops/ alfalfa, irrigated crops/other, orchard, vineyard, redwood plantation, ruderal, riparian, vernal pool, aquatic, and developed (Table 5.10-2, Figure 5.10-3). These biotic habitats and associated vegetation and wildlife are described in further detail below. Plant communities were described in terms of dominant tree, shrub, and herbaceous vegetation composition and, when possible, classified according to the nomenclature of Holland (1986) and Sawyer and Keeler-Wolf (1995). Figure 5.10-1 shows the distribution of these habitats and land use types. Table 5.10-2 -- Summary of Biotic Habitats and Land Use Types Present In the Study Area Habitat type Acreage Percent of total Irrigated Row Crop --Alfalfa 1,789.8 14.0% Aquatic 57.9 0.5% California Annual Grassland 415.5 3.3% Orchard 3,562 27.8% Redwood Plantation 7.8 0.1% Riparian 16.1 0.1% Irrigated Row Crop --Other 2,743.6 21.5% Ruderal 154.9 1.2% Vernal Pool 0.8 0.0% Vineyard 49.2 0.4% Developed/Other: 3,970.5 31.0% Total: 12,768 100% Sources: HT Harvey, 2010, HT Harvey, 2006, HT Harvey, 2002 CMCA, 2010 CITY of PATTERSON ~ General Plan EIR 5.10-3 Figure 5.10-1: Habitats within the General Plan Study Area CITY of PATTERSON ~ General Plan EIR 5.10-4 California Annual Grassland California annual grassland occurs in the area west of Interstate 5 and comprises approximately 415.46 acres (3.3%) of the Study Area. This habitat covers gently rolling to steeply sloped (75% slope) terrain dissected by ephemeral drainages and Del Puerto Creek in the north. The terrain north of Del Puerto Creek and along the southwest near I-5 is very steep with some exposed rocky cliffs near Del Puerto Creek. This habitat is primarily dominated by non-native annual grasses, but also supports a variety of native herbs. The dominant grass species in these areas are ripgut brome (Bromus diandrus) and slender oat (Avena barbata). Native herbs present within the California annual grassland habitats include Great Valley gumweed (Grindelia camporum var. camporum), Heermann’s tarweed (Holocarpha heermannii), and California poppy (Eschscholzia californica). The non-native grasslands found on the site are productive wildlife habitat. Grassland species such as mourning dove (Zenaida macroura), savannah sparrow (Passerculus sandwichensis), California ground squirrel (Spermophilus beecheyi), and deer mouse (Peromyscus maniculatus) forage on the seed crop and attract predators such as the gopher snakes (Pituophis melanoleucus), American kestrel (Falco sparverius), red-tailed hawk (Buteo jamaicensis), and coyote (Canis latrans). Winter migrants to this site include Say’s phoebe (Sayornis saya) and American pipit (Anthus rubescens), while the spring and summer months bring western kingbirds (Tyrannus verticalis). Irrigated Crops/Alfalfa Irrigated alfalfa (Medicago sativa) comprises 1,789.8 acres (14.0%) of the Study Area. Black mustard (Brassica nigra), Johnsongrass (Sorghum halepense), Italian ryegrass (Lolium multiflorum), and other ruderal, weedy species are also found sporadically throughout the fields. These crops are primarily flood- irrigated using water that is diverted from the laterals present on the site to irrigation trenches located on the periphery of the fields. Because it is less frequently disturbed than other crops, alfalfa can provide attractive habitat for some wildlife. During irrigation, flocks of birds including great blue herons (Ardea herodias), snowy egrets (Egretta thula), white-faced ibis (Plegadis chihi), long-billed curlews (Numenius americanus), and American crows (Corvus brachyrhynchos) are frequently observed feeding on invertebrate life and small mammals forced to the surface by sheets of water. Alfalfa frequently supports large populations of gophers (Thomomys sp.) and voles (Microtus sp.), which are prey for raptors such as red-tailed hawks, Swainson’s hawks (Buteo swainsoni), and northern harriers (Circus cyaneus). Irrigated Crops/Other Irrigated crops/other comprise 2,743.6 acres (21.5%) of the Study Area. This habitat type includes plowed or recently disked fields, hay, pasture, fallow fields (previously farmed but not currently planted), and row crops including broccoli and corn. Black mustard, Johnsongrass, Italian ryegrass, and other ruderal, weedy species are also found sporadically throughout the fields. These crops are primarily flood-irrigated using water that is diverted from the laterals present on the site to irrigation trenches located on the periphery of the fields. Species that occur in cultivated habitats are generally widespread species accustomed to disturbances such as American kestrels, American crows, killdeer (Charadrius vociferous), western meadowlarks (Sturnella neglecta), Brewer’s blackbirds (Euphagus cyanocephalus), and house finches (Carpodacus mexicanus). CITY of PATTERSON ~ General Plan EIR 5.10-5 5.10 BIOLOGICAL RESOURCES Fallow fields are likely to have larger populations of small mammals, such as gophers, than actively farmed lands and may be more likely to provide nesting habitat for birds such as killdeer, mourning doves, and red-winged blackbirds (Agelaius phoeniceus). Raptors also prey upon small mammals within fallow fields. Orchard Orchards comprise approximately 3,562 acres (27.8%) of the Study Area. Apricot (Prunus armeniaca), English walnut (Juglans regia), and almond (Prunus dulcis) cultivars were the primary orchard crops. The orchards throughout the Study Area are generally maintained with few weedy species, and the herbaceous layer consisted primarily of barren soil at the time of the survey. Orchards provide limited habitats for wildlife, as frequent disturbances associated with crop production such as pruning, spraying, harvesting, watering, and other ground disturbances limit the potential for most wildlife species to persist in these habitats. However, some animals such as the side-blotched lizard (Uta stansburiana) persist under these conditions. Birds such as American crows and yellow-billed magpies (Pica nuttalli) utilize nut crops and can be quite abundant. Burrowing animals such as California ground squirrels and gophers are normally actively discouraged because of damage these animals can cause to irrigation systems. Redwood Plantation A single redwood (Sequoia sempervirens) plantation occurring in the northeast section of the Study Area comprised approximately 7.82 acres (0.1%) of the Study Area. Overall plant diversity was low due to the close spacing of the trees. This small isolated redwood plantation is of limited value to wildlife due to low species and structural diversity. As with many rural woodlots, it may provide roosting and nesting habitat for common bird species such as American crows, mourning doves, and house finches. Vineyard Vineyards comprise approximately 49.16 acres (0.4%) of the Study Area.

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