Summary of Del Puerto Canyon Reservoir Final Environmental Impact Report, Part II

In Part I, we looked at a few of the reasons the proposed dam at the mouth of Del Puerto Canyon has caused such a great deal of opposition within the local community.  Some of the arguments against the dam include the risk of flooding that a dam failure would present to the city of Patterson, the loss of educational and recreational access to the lower canyon, destruction of Native American cultural sites, and loss of access to sites of geological and paleontological significance.

While there are many valid reasons why this canyon should not be flooded, perhaps the most significant to me, as a naturalist, is the loss of wildlife habitat and disruption of wildlife corridors that would follow.  

Below are excerpts from the environmental impact report (read the full text here and here) regarding the specific species of wildlife that have the potential to be displaced by the damming and flooding of Del Puerto Canyon.

Regarding terrestrial biological resources (i.e. wildlife):

(Quotes below taken from the EIR pdf pages 139-144.  Access the full text here.)

"The study area includes the footprints of the proposed project infrastructure, the maximum inundation area, areas where utilities may need to be relocated, any areas of potential disturbance related to constructing the proposed project, and a 300 foot buffer around these areas to identify sensitive biological resources that could be affected during project construction and/or operations." 

A "general habitat evaluation to determine whether suitable habitat exists for special-status plant and animal species... was performed by ICF biologists May 2019 through July 2019."  This included "placing motion activated trail cameras near the mouth of Del Puerto Canyon for a total of two weeks in mid to late June 2019," and "recording wildlife observations made during field surveys." 

"To prepare for the field surveys, biologists reviewed existing resource information related to the project to evaluate whether special-status species or other sensitive biological resources... could occur in the study area."  Sources reviewed included "California Natural Diversity Database (CNDDB) animal species records within 5 miles of the study area."  (The CNDDB is "an inventory of the status and locations of rare plants and animals in California. CNDDB staff work with partners to maintain current lists of rare species, as well as to maintain an ever-growing database of GIS-mapped locations for these species."  Learn more here.)

"Natural communities of special concern are habitats considered sensitive because of their high species diversity, high productivity, unusual nature, limited distribution, or declining status. Local, state, and federal agencies consider these habitats important, and compensation for loss of sensitive communities is generally required by agencies. The CNDDB contains a current list of rare natural communities throughout the state... USFWS [US Fish and Wildlife Service] considers certain habitats, such as riparian communities, important to wildlife; and the U.S. Army Corps of Engineers (USACE) and Environmental Protection Agency (EPA) consider stream habitats important for water quality and wildlife."

"One natural community of special concern, riparian woodland is present in the study area. Riparian woodland in the study area is classified as Fremont cottonwood forest, which has a State rarity of S3, which is defined as vulnerable in the state due to a restricted range, relatively few populations, recent and widespread declines, or other factors making it vulnerable to extirpation."

Special Status Wildlife (those listed as state or federally threatened or endangered) in the Canyon:

(Quotes below taken from the EIR pdf pages 146-167.  Access the full text here.)

ICF wildlife biologists recognized 22 special status wildlife species "that may occur in the study area or that could be affected by the proposed project."

Bear in mind, even if the CNDDB does not record a species as occurring in the area, and that species was not observed during this very brief survey of the Canyon, it does not necessarily follow that the species is entirely absent!  If suitable habitat is present, there is always the chance of its present or future occurrence.  And, to quote one very famous, albeit deeply historically flawed Disney movie, "If you cut it down, you will never know!"  If the canyon is dammed and flooded, the habitat lost forever, we will never know what treasures it held.

Below is a list of listed special status wildlife species that occur or may occur within the study area.

Vernal Pool Fairy Shrimp (federally threatened): Moderate potential for occurrence.  "Suitable habitat is present in the study area."

Vernal Pool Tadpole Shrimp (federally endangered): Moderate potential for occurrence.  "Suitable habitat is present in the study area."

Valley Elderberry Longhorn Beetle (federally threatened): High potential for occurrence.  "Several elderberry shrubs are present along and in the vicinity of Del Puerto Creek in the study area below 500 feet elevation and could provide host plants for the species. An exit hole was observed on one of the shrubs. There are no CNDDB records within 5 miles of the study area. The closest CNDDB record is approximately 8 miles northeast of the study area."

California Tiger Salamander (federally and state listed as threatened): Moderate potential for occurrance.  "Stock ponds in the study area represent suitable aquatic breeding habitat. Grasslands throughout the study area are located within 1.24 mile of potential breeding ponds and contain numerous small mammal burrows and soil cracks that could be used as upland habitat. There are no CNDDB records within 5 miles of the study area. The closest CNDDB record is 8.5 miles northwest from the study area."

California Red-legged Frog (federally threatened, California species of special concern): Moderate potential for occurrence.  "Del Puerto Creek and a stock pond within the study area represent suitable aquatic habitat. Suitable upland habitat is present within 300 feet of suitable aquatic habitat and dispersal habitat is present within 1 mile of aquatic habitat. The closest CNDDB records for the species are approximately 15 miles south and 14.75 miles west."

Foothill Yellow-legged Frog (candidate for state listing as threatened, California species of special concern): Moderate potential for occurrence.  "Del Puerto Creek and adjacent riparian habitat represents suitable habitat in the study area. There are 4 CNDDB records within 5 miles of the study area, with the closest record on the southwestern boundary of the study area." 

Swainson's Hawk (state threatened): High potential for occurrence.  "Suitable nesting and foraging habitat are present in the study area and the species was observed during field surveys. There are 2 CNDDB records within 5 miles of the study area, with the closest record within the study area."  eBird lists dozens of Swainson Hawk sightings within the study area.

Golden Eagle (California fully protected species): High potential for occurrence.  "Suitable nesting and foraging habitat are present in the study area and the species was observed in flight during field surveys. There are no CNDDB records within 5 miles of the study area. The closest CNDDB record is approximately 10.5 miles south of the study area."  eBird lists dozens of Golden Eagle sightings within the study area.  "Studies by others indicate that there are golden eagle nesting territories within 5 miles of the study area (Wiens et al. 2015, Hunt et al. 2017 and Dunk et. al. 2019). Potential foraging habitat for golden eagle is present in the study area and the species was observed in flight during the wildlife surveys. Potential nesting habitat occurs to the west of the study area where there are cliffs and escarpments, as well as where there are trees within the study area." 

White-tailed Kite (California fully protected species): High potential for occurrence.  "Suitable nesting and foraging habitat is present in the study area. There are no CNDDB records within 5 miles of the study area. The closest CNDDB record is approximately 21 miles from the study area."  

Least Bell's Vireo (State and federally endangered): Low potential for occurrence.  "The study area is in the historic range of the species. There has only been one documented nesting in the San Joaquin Valley in recent years but there are not sustained populations. The study area supports minimal areas of riparian vegetation, which also lack the dense riparian vegetation required by the species. There is 1 CNDDB record [from 1928] within Del Puerto Canyon; however, the specific location within the canyon is unknown."

Tricolored Blackbird (State threatened): Moderate potential for occurrence.  "Suitable foraging habitat is present in the study area; however, the study area supports minimal areas of emergent marsh or upland nesting sites, which are not large enough to support a nesting colony. There are 3 CNDDB records within 5 miles of the study area, with the closest record approximately 1.5 miles east of the study area."  eBird lists dozens of Tricolored Blackbird sightings within the study area.

San Joaquin Kit Fox (federally endangered, state threatened): Moderate potential for occurrence.  "Suitable open grassland and friable soils are present in the study area, and burrows that range between 5 to 8 inches in diameter were observed during field surveys. There are 4 CNDDB records within 5 miles of the study area, with the closest record within the study area."  Perhaps most significantly, the study area "may be used as a dispersal corridor between more suitable habitat to the south and areas to the north."

Non-listed special status species in the Canyon:

(According to California Department of Fish and Wildlife, "A Species of Special Concern (SSC) is a species, subspecies, or distinct population of an animal native to California that currently satisfies one or more of the following (not necessarily mutually exclusive) criteria: is extirpated from the State or, in the case of birds, is extirpated in its primary season or breeding role; is listed as Federally-, but not State-, threatened or endangered; meets the State definition of threatened or endangered but has not formally been listed; is experiencing, or formerly experienced, serious (noncyclical) population declines or range retractions (not reversed) that, if continued or resumed, could qualify it for State threatened or endangered status; has naturally small populations exhibiting high susceptibility to risk from any factor(s), that if realized, could lead to declines that would qualify it for State threatened or endangered status.")

(Quotes below taken from the EIR Vol. II pdf pages 197-212.  Access the full text here.)

Western Spadefoot Toad (California species of special concern): Moderate potential for occurrence.  "Suitable aquatic habitat (seasonal wetlands and stock ponds) and upland habitat (grasslands) is present in the study area. There are 4 CNDDB records within 5 miles of the study area, with the closest record just outside the southwestern boundary of the study area."

Western Pond Turtle (California species of special concern): Moderate potential for occurrence.  "Suitable aquatic habitat is present in the study area in Del Puerto Creek. No pond turtles were observed during surveys. There are no CNDDB records within 5 miles of the study area. The closest CNDDB record is approximately 7 miles west of the study area."

Blainville's Horned Lizard (California species of special concern): Moderate potential for occurrence.  "Suitable sandy soils are present in the study area. There are no CNDDB records within 5 miles of the study area. The closest CNDDB record is approximately 15.5 miles from the study area." 

Northern California Legless Lizard (California species of special concern): Moderate potential for occurrence.  "Suitable sandy soils are present in the study area. There is 1 CNDDB record within 5 miles of the study area, approximately 5 miles southwest of the study area."

San Joaquin Coachwhip (California species of special concern): High potential for occurrence.  "Suitable open grassland and small mammal burrows are present in the study area. There is 1 CNDDB record within 5 miles of the study area, approximately 1 mile east of the study area."

Western Burrowing Owl (California species of special concern): Moderate potential for occurrence.  "Suitable grassland habitat with small mammal burrows is present in the study area. No burrowing owls were observed in the study area during reconnaissance level surveys. There are 2 CNDDB records within 5 miles of the study area, with the closest record within the study area."  However, eBird lists at least a dozen Burrowing Owl sightings within the study area.  "Potential habitat for western burrowing owl is present in grasslands throughout the study area, and numerous ground squirrel burrows that could be utilized by western burrowing owl were observed during the wildlife surveys." 

Loggerhead Shrike (California species of special concern): High potential for occurrence.  "Suitable nesting and foraging habitat are present in the study area and the species was observed during field surveys. There is 1 CNDDB record approximately 1.5 miles east of the study area."  eBird lists hundreds of Loggerhead Shrike sightings within the study area.

Grasshopper Sparrow (California species of special concern): High potential for occurrence.  "Suitable habitat is present in the lower grassland portions of the study area. There are no CNDDB records within 5 miles of the study area but there are several eBird observations within the lower portion of Del Puerto Canyon during the breeding season."

Western Red Bat (California species of special concern): Moderate potential for occurrence.  "Suitable roosting sites are present in riparian woodland and ornamental trees, and suitable open habitat for foraging is present in the study area. There are no CNDDB records within 5 miles of the study area. The closest CNDDB record is approximately 14 miles from the study area."

Pallid Bat (California species of special concern): Moderate potential for occurrence.  "Suitable roosting habitat joints in Del Puerto Creek culvert beneath I-5, abandoned structures, rock outcrops, and trees with cavities in riparian woodlands. Suitable open habitat for foraging is present in the study area. There are no CNDDB records within 5 miles of the study area. The closest CNDDB record is approximately 12 miles from the study area."

Western Mastiff Bat (California Species of Special Concern): Moderate potential for occurrence.  "Suitable rocky outcrops and joints within the Del Puerto Creek culvert beneath I-5 represent suitable roosting habitat and suitable open habitat for foraging are present in the study area. There are no CNDDB records within 5 miles of the study area. The closest CNDDB record is approximately 17 miles from the study area."  

American Badger (California Species of Special Concern):  High potential for occurrence.  "Suitable habitat with friable soils is present in the study area, and burrows with badger diggings were observed during field surveys. There is 1 CNDDB record within 5 miles of the study area, approximately 3 miles south of the study area."  

Additionally, "non-special-status migratory birds have the potential to nest in the study area. Although these species are not considered special-status wildlife species, their occupied nests and eggs are protected by California Fish and Game Code Sections 3503 and 3503.5 and the Migratory Bird Treaty Act. Fifty-seven bird species were observed in flight or roosting in the study area during the 2019 surveys. No nesting surveys were conducted as part of the reconnaissance level surveys. Bird observation records reviewed in the Cornell Lab of Ornithology’s online bird observation database, called eBird, indicate that at least 116 bird species have been observed within the study area (eBird 2019)."  (EIR Vol. I, p.167)

"Non-Special-Status Roosting Bats Roosting non-special-status bats have the potential to forage and roost in trees, structures, and rock outcrops in the study area. CDFW typically recommends that substantial roost colonies of non-special status bats (such as Mexican free-tailed bat) be protected from disturbance, especially during maternal roosting and hibernation." (EIR Vol. I, p.167)

In summary, the EIR states: "The reservoir and associated facilities would affect potential habitat for a variety of terrestrial and aquatic species. The EIR will evaluate impacts on candidate, sensitive or special status species; effects on riparian habitat and other natural communities, effects on state and federally protected wetlands; impacts on movement of native wildlife and effects on nursery sites, and potential conflicts with local policies and ordinances protecting biological resources, and a listing of mitigation measures to help address impacts." 

Stay tuned for Part III