The project partners (Del Puerto Water District and San Joaquin River Exchange Contractors Water Authority) supply Central Valley Project (CVP) water to thousands of acres of highly productive farmland in Stanislaus, San Joaquin, Merced, Fresno, and Madera counties. CVP water is imported south from the Sacramento-San Joaquin Delta (Delta) through the Delta-Mendota Canal. For more than two decades, droughts and pumping restrictions imposed to protect fish habitat and water quality have caused shortages and volatility in water deliveries exported from the Delta. The reservoir would provide locally controlled and owned water storage for farmers and wildlife refuges in the area during dry months and droughts and will allow the project partners to better serve their customers, which in turn will support the local economy and benefit the region.

Draft Environment Impact Report reference: Chapter 1, Page 1-2, Section 1.1.1 “Need for Water Storage."

A reliable water supply is key to the vitality of our region. Water supplies would be stored in the reservoir at times when they are available to the project partners and released back to the Delta-Mendota Canal when needed for agricultural irrigation and wildlife refuges. The reservoir would store Central Valley Project water supplies originating from the Sacramento-San Joaquin Delta and delivered to the water agencies via the Delta-Mendota Canal. Storing water from wet periods also helps improve groundwater supply conditions for residents and municipal supplies on the westside of the Valley by reducing groundwater pumping in dry periods and droughts.

The project partners will own and operate the proposed facilities. The Del Puerto Water District and the San Joaquin River Exchange Contractors Authority are State of California public agencies; therefore, the project will be a public water agency owned facility. Those served by the reservoir will be the users of the stored water and will pay for the project.

These landowners include hundreds of family farms in the region—the average farm size is approximately 120 acres. These farms use water to support livestock, poultry, and dairy and grow diverse crops, including fruits, nuts, and vegetables, many of which carry the organic label. The principal crops grown in the area are almonds, tomatoes, apricots, walnuts, oats, wheat, barley, grains, broccoli, corn, melons, dry beans, peaches, citrus, spices, cherries, wine grapes, and olives. Our farmers also contribute to the local and regional economy with jobs (on-farm, packing, processing, and shipping) purchasing of equipment and supplies, local taxes (e.g., 25% of Patterson school bonds), and support for local businesses, schools, activities, and charities.

In addition, wildlife refuges in the region will also receive water from the proposed project and will pay for the water delivered to them. The project partners are also seeking supplemental funding. The 2016 Water Infrastructure Improvements for the Nation Act (WIIN Act) could provide up to 25% of construction costs for federal benefits such as Central Valley Project (CVP) water supply reliability, flood control, refuge water supply, and storage currently unavailable to the area's wildlife refuges.

The reservoir will provide a local, public water agency controlled storage facility that benefits farmlands, wildlife refuges, and area communities. The project will:

• Capture and manage Del Puerto Creek storm flows to increase flood protection and reduce insurance requirements for residents and businesses in the Del Puerto Creek floodplain, in north Patterson.
• Improve local water supplies. The stored storm water will be used to improve infiltration in the creek, improve local groundwater, and increase the City of Patterson water supplies.
• Improve water supply reliability for agriculture, which in turn supports the local and regional economy.
• Improve regional groundwater conditions. Using water stored in the reservoir for irrigation will reduce groundwater pumping and improve drinking water supplies for west side communities, including Crows Landing, Dos Palos, Firebaugh, Grayson, Gustine, Los Banos, Mendota, Newman, Patterson, and Westley. Many of these are disadvantaged communities with limited resources to address their water supply issues.
• Provide water for wildlife refuges in the area, which provide critical habitat for birds and animals and recreation for the region.

Draft Environment Impact Report reference: Chapter 1, Page 1-3, Section 1.2 “Proposed Project Objectives.”

Yes. The dam will be designed and built to meet all current requirements of the California Division of Safety of Dams, and all applicable federal dam safety requirements. The design will be based on a detailed seismic hazards analysis for several nearby faults, the closest being the San Joaquin Fault, which runs north-south near the I-5 alignment. Other nearby faults are the Ortigalita Fault and Greenville Fault, 25 miles and 30 miles away, respectively. None of these faults is considered active, as none has had activity along them within the last 11,000 years. A 6.1 earthquake was recorded in 1881 (not on any fault) about six miles from where Del Puerto Canyon Reservoir would be located. Once the seismic hazards analysis is complete, the dam will be designed to withstand the maximum credible earthquake on nearby faults. That maximum credible earthquake is estimated at 6.9 for nearby faults. The dam design would provide a margin of safety. A seismic monitoring system will be built into the dam and remain in service throughout its life to monitor structural integrity continuously.

The project partners prepared a video describing design measures for earthquake safety. You can view the video here.

If built, the new reservoir would eliminate flooding in the Del Puerto Creek floodplain along the creek and in north Patterson. This area could then be removed from the FEMA 100-year flood maps (1% probability of flooding each year), which would eliminate mandatory flood insurance requirements for residents and businesses in this area.

It is important to note that the Del Puerto Canyon Reservoir would be an off-stream facility, unlike many reservoirs in the State that are located on major rivers such as the Sacramento, Feather, American, and San Joaquin Rivers. Being an off-stream reservoir means it is located in a very small watershed and filled by pumping water up into the reservoir from a downstream source. An analysis of the potential for extreme storm flows, known as the Probable Maximum Flood, is used to establish the design of the dam and spillway, ensuring safe operation even during extreme flood conditions.

Dam designers are also required to simulate the potential inundation zones if a dam were to fail. This information is intended to inform emergency planning and is required for all dams under state jurisdiction. The Del Puerto Canyon Reservoir facilities will be designed to the most stringent current federal and state dam design standards. The design, construction, and operation of the project would be overseen by the California Division of Safety of Dams, whose charge it is to regulate dams to prevent failure, safeguard life, and protect property. These design standards apply to more than 60 dams in California of similar size and hazard classification.

The State of California has permitting, inspection, and enforcement authority for dams in the state. The State reviews plans and specifications for dam construction and major repair work; inspects construction work on new and existing dams; and reviews and approves Emergency Action Plans. In addition to regular inspections, the dam would include a monitoring system to proactively report any issues before they develop into a risk.

The project partners prepared a video describing flooding, inundation zones, and insurance. You can view the video here .

The situation at Anderson Dam demonstrates that dam safety oversight in California works effectively. The dam was built in 1950 and is owned and operated by Valley Water (formerly known as Santa Clara Valley Water District). Because Anderson Dam is located in California and includes hydroelectric power generation, its operation and safety are overseen by both the California Division of Safety of Dams and the Federal Energy Regulatory Commission. In 2011, dam safety inspections identified potential risk of dam failure in an earthquake. The dam owners were ordered to immediately reduce the amount of stored water behind the dam to reduce the risk to downstream communities. Since then, the dam has operated at less than 60% of capacity until seismic improvements are complete. During design of the improvements, it was determined that the foundation of the existing dam needed to be fully excavated and replaced, resulting in increased costs and schedule delays. Work is again underway to design a replacement dam. In February 2020, the Federal Energy Regulatory Commission ordered the reservoir drained before the end of 2020, and that it remain drained until a replacement dam is built that meets current dam design standards. Further information about the status of Anderson Dam can be found here .

The circumstances at Oroville Dam also demonstrate that dam safety oversight in California works effectively. Oroville Dam was completed in 1967. In February 2017, an extreme storm caused record inflows to Lake Oroville. A crack developed in the dam’s spillway (referred to as a “failure”) which required the use of the emergency spillway to maintain safe water levels behind the dam. As a safety precaution, approximately 188,000 people downstream of the dam were evacuated. The dam was not at risk of failing, and there were no losses to downstream properties or lives.

The failures of two, private, hydroelectric dams in Michigan were caused by extreme storms and flooding. The Edenville Dam was built in 1924 at the confluence of the Tittabawassee and Tobacco Rivers. The Edenville Dam owners had been cited by federal regulators for failing to upgrade the dam spillway to accommodate large rainstorms. In 2018, the regulators revoked the owner's operating license for failing to address the safety issues. The Tittabawassee River is more than 70 miles long and drains an area of more than 2,400 square miles. Michigan has only two staff and a supervisor to oversee more than 1,000 dams. In contrast, California has more than 70 staff to oversee about 1,200 dams water.ca.gov/Programs/All-Programs/Division-of-Safety-of-Dams .

The dam problems in Michigan and Oroville are distinct from the conditions at the proposed Del Puerto Canyon Reservoir. Edenville Dam was constructed 96 years ago, when dam design standards were less stringent. Both Edenville and Oroville dams are located on large watersheds that can be impacted by large storms. The proposed reservoir is an offstream storage facility, meaning that it is filled primarily from downstream water sources, not from watershed runoff. Del Puerto Creek is an intermittent stream in a much smaller watershed (74 square miles) than Edenville (2,400 square miles) and Oroville (3200 square miles). The dam will be designed with a spillway and emergency drawdown facilities to accommodate the probable maximum flood.

No, FEMA does not require persons downstream from a dam to purchase flood insurance. The dam would reduce flooding in lower portions of Del Puerto Creek, which would reduce flood insurance requirements for residents and businesses currently located within the FEMA 100-year flood zone for that creek. The project partners will carry flood liability insurance, which will cover third parties, including Patterson residents.

Draft Environment Impact Report reference: Figure 3.11-1 in Section 3.11, City of Patterson Flood Insurance Rate Map.

There are more than 90,000 dams in the United States. There has never been an instance of a landslide causing overtopping of any of these dams. Because the hills along the west side of the Central Valley are a common area for landslides, extensive geotechnical evaluations are underway to further characterize landslide risks for the reservoir. These evaluations will be used to ensure that the dam structure is anchored to bedrock and that design and construction measures will be used to stabilize or remove potential landslides.

Approximately 3.5 miles of Del Puerto Canyon Road is located within the reservoir inundation area. DPWD and the Exchange Contractors are working with Stanislaus County public works department to identify the most appropriate new roadway alignment for this portion of Del Puerto Canyon Road. Challenges for relocation include the steepness of the canyon and the potential for landslides. The relocated road would have one 12-foot wide travel lane with a paved 4-foot shoulder in each direction (Draft EIR page 2-8). Bicycling would be safer with the wider shoulders. The elevation profile for the proposed roadway relocation can be viewed on the Resources page. Occasional turnouts could be developed to accommodate birders, photographers, and other viewing.

Draft Environment Impact Report reference: Chapter 2, page 2-8, Section 2.2.3 “Roadway Relocation” and page 2-21, Section 2.4.6 “Roadway Relocation.”

Yes. The project team is in discussions with PG&E and Shell to determine the best options. See section 2.2.4 Utility Relocation of the Draft EIR for additional information. Additionally, as more information becomes available, it will be posted on this page.

Draft Environment Impact Report reference: Chapter 2, page 2-9, Section 2.2.4 “Utility Relocation” and Chapter 2, page 2-21, Section 2.4.7 “Utility Relocation.”

The lands that would be inundated by the proposed reservoir are currently privately owned with no public access. Frank Raines OHV Park, approximately 11.4 miles west of the proposed reservoir footprint, would still be accessible via a relocated and improved Del Puerto Canyon Road. The project partners would purchase enough private property to build and operate the reservoir and have publicly suggested that they would be willing to support the purchase of additional lands, if necessary, to support other uses. The property purchased around the reservoir could be used for these other uses as long as they do not conflict with the primary purposes of the reservoir. The project partners are supportive of further uses of the lands, such as cattle grazing or recreation, but uses would have to be managed by a partner, e.g., ranch manager or public recreation agency. The project partners continue to work with Stanislaus County and the City of Patterson to develop the potential recreational opportunities around the proposed reservoir.

Area landowners have expressed concerns about the possibility of increased trespassing with the addition of the reservoir. The project partners would be responsible for security of the reservoir and related facilities. Security would be designed as part of the reservoir facilities, and intrusions would be enforced by reservoir operators with the continued support of local law enforcement.

Del Puerto Canyon Reservoir would not be suitable for water-based recreation because of steep shorelines and fluctuating water levels from wet periods to dry periods. Generally, in the summer, the reservoir will be very low or almost empty. The water will be used to meet the reservoir's primary purpose—irrigation water for crops in the region and water supplies for wildlife refuges.

The project partners are coordinating with Stanislaus County and the City of Patterson to assist in identifying recreational amenities that would not conflict with the primary purposes of the reservoir. The County or City could potentially develop activities such as hiking, picnicking, or an educational center. The County and/or City would be responsible for determining the necessary planning steps and funding needs, and the project partners have committed to participating in a process that develops this potential, which is underway.

The relocated roadway would continue to provide access to birding and bicycling. As noted above under roadway relocation, the new road will include a larger shoulder for safer bicycling and turnouts could potentially be developed for birders, photographers, etc.

The project partners are open to further discussion and exploration of this concept.

Truck traffic will be managed during the construction of both the roadway and dam to minimize delays and dust. It is expected that the improvements to the I-5/Sperry Avenue interchange and Del Puerto Canyon Road relocation will be completed before dam construction begins, however the schedule for construction of interchange improvements is outside the control of the project partners. The project partners will be working with Stanislaus County and Caltrans to ensure that interchange improvements happen as soon as possible. Stringent dust control measures will be in place throughout construction.

Draft Environment Impact Report reference for project construction: Chapter 2, page 2-15, “Construction Considerations,” page 2-19, section 2.4.10 “Environmental Commitments.” Chapter 3, page 3.3-1 through page 3.3-30, section 3.3 “Air Quality” – Note: this section evaluates the potential air quality impacts associated with implementation of the proposed project.

The only hazardous materials that will be on-site during construction are fuels and lubricants needed for heavy equipment operations (e.g., diesel fuel). Standard measures for preventing and controlling spills will be in place.

Draft Environmental Impact Report reference: Chapter 3, page 3.10-1 through 3.10-13, Section 3.10, "Hazards and Hazardous Materials." This section describes the environmental setting for hazards and hazardous materials in the study area, including the project site and adjacent areas that could be affected by the use or presence of hazardous materials.

The project team is evaluating and documenting the impacts to riparian and grassland habits. The final location and amount of habitat restoration will be worked out with the state and federal natural resources agencies as part of project permitting.

Through the required environmental reviews, the project impacts to all species, including protected species, have been evaluated, and mitigation is proposed to avoid and minimize significant impacts. Mitigation to protect birds will be included in the project.

Draft Environmental Impact Report reference: Chapter 3, page 3.4-1 through page 3.4-72, section 3.4 “Biological Resources—Terrestrial” – This section evaluates the potential terrestrial biological impacts (and mitigations) associated with implementation of the proposed project. Chapter 3, page 3.5-1, section 3.5, Biological Resources—Fish evaluates the potential biological resource impacts to fish.

The creek flows will be captured by the dam and released to the creek below the dam in a way that reduces flooding and promotes groundwater recharge. Moderating the flows below the proposed dam would also improve habitat along the creek.

Draft Environmental Impact Report reference: Chapter 2, page 2-13, “Reservoir Releases.”

There are no tribal cultural resources, including sacred lands, recorded as present in the project area. The project partners have consulted with the Native American Heritage Commission and are coordinating with the North Valley Yokuts Tribe, to ensure respectful treatment of the existing archaeological sites and any artifacts that may be found within the project area.

Draft Environmental Impact Report reference: Chapter 3, Section 3.14, pages 3.14-1 through 3.14-5, “Tribal Cultural Resources.” This section evaluates the potential impacts on Tribal Cultural resources associated with implementation of the proposed project

The environmental studies document the known resources in the canyon and acknowledge that previously undiscovered resources could be unearthed during construction. If paleontological resources are located during construction they can be relocated, and cultural resource would be documented and protected from damage during construction before the reservoir is filled. The project partners will be working with state agencies and local resource experts to develop a preservation plan.

Draft Environmental Impact Report reference: Chapter 3, page 3.6-1 through page 3.6-12, section 3.6, "Cultural Resources.” This section evaluates the potential impacts on cultural resources associated with implementation of the proposed project.