The Cache Creek Improvement Program (CCIP) requires that the Cache Creek Technical Advisory Committee (TAC) produce an annual status report in January of each year for the Yolo County Board of Supervisors. This annual report provides a record of the implementation of the Cache Creek Resources Management Plan (CCRMP) and CCIP for the 2019 Water Year, which spans the period of October 1, 2018 to September 30, 2019. The report is intended to: 1) document the previous year's monitoring results, field observations and any completed in-channel restoration or stabilization projects; 2) provide analysis of data and trends; and 3) identify recommendations and projects for the next year. This report represents a critical component of the adaptive management of lower Cache Creek.
Status of In-Channel Maintenance Regulatory Approvals
Lower Cache Creek is subject to regulation by various state and federal agencies, such as: the US Army Corps of Engineers, the US Fish and Wildlife Service, the State Department of Fish and Game, and the State Water Resources Control Board. County staff have secured programmatic regulatory approvals which authorize certain in-channel maintenance activities (such as gravel bar skims, bank repairs, vegetation removal, etc.) from two (2) of the required three (3) agencies: the State Department of Fish and Wildlife and the State Water Resources Control Board. Staff has met with the US Army Corps of Engineers and has submitted a memo to the Corps, seeking concurrence that in-channel projects, designed to the County's "In-Channel Maintenance" ordinance specifications and involving only the removal of material from the channel (i.e. all cut/dredging and no fill/discharge) are exempt from Army Corps jurisdiction under the "Tulloch Rule". Without a federal nexus, in-channel projects could be implemented under the County's existing state approvals and covered by the Yolo Habitat Conservancy's HCP/NCCP.
Staff is working with the County's federal advocates to seek concurrence on this issue.
Background
The Cache Creek Area Plan (CCAP) was adopted by the Yolo County Board of Supervisors in 1996. The CCAP is comprised of the Off Channel Mining Plan (OCMP) and the Cache Creek Resources Management Plan (CCRMP). The goals of the CCAP effort are protection of groundwater, preservation of agriculture, restoration of Cache Creek, and regulation of commercial mining. Implementation of the CCRMP is discussed further below.
The CCRMP (adopted August 20, 1996, amended August 15, 2002, and December 17, 2019) is a creek management plan. It eliminated in-channel commercial mining and established an improvement program for implementing on-going projects to improve channel stability and restore habitat along the creek banks. The CCRMP provides a policy framework for the restoration of 14.5 miles of lower Cache Creek and includes specific implementation standards. The Cache Creek Improvement Program (CCIP) is the implementation plan for the CCRMP and identifies specific categories of projects that include: bank stabilization, channel maintenance, re-vegetation and habitat restoration.
The CCIP is overseen by a Technical Advisory Committee (TAC) comprised of three scientists charged with advising the County on implementation of in-channel restoration and stabilization projects. The work of the TAC is, by design, an iterative process driven by on-going monitoring and technical feedback on creek performance. The TAC is comprised of a fluvial geomorphologist, a hydraulic engineer and a riparian biologist.
In January of each year the TAC is required to prepare, and present to the Board of Supervisors, an annual status report for their activities of the previous year. This report fulfills that obligation and provides an opportunity for the TAC, community, and stakeholders to step back and take a larger perspective in looking at both the creek and the CCRMP with a critical eye for improvement.
Summary of Findings
Hydrologic and Water Quality Findings
The 2019 Water Year was a dry year for Cache Creek and the Sacramento River Valley. There were two elevated flow events during the water year February. Water quality sampling data remained within or below the ranges measured in previous years and did not exceed any recommended contaminant limits. Some contaminants continued to not be detected in Water Year 2019 as in the last several years.
Geomorphology Findings
Water Year 2019 was much wetter than 2018 in the Cache Creek basin. Consistently wet hydrologic conditions resulted in numerous weeks of sustained flow above 5,000 cfs in Cache Creek, and two peak flows greater than 20,000 cfs. These relatively high flows contributed to the third highest delivery and transport of sediment to and through the CCRMP area over the last 15 years. Evidence of elevated sediment transport in 2019 was observed throughout the 2019 Creek Walk and included significant erosion at the PG&E Palisades site as well as significant deposition in the vicinity of numerous bridge crossings. Relatively high sediment transport was also captured in the comparison of 2017 and 2019 topographic conditions. Similar to 2017, there was actually net erosion throughout the CCRMP area, with both localized deposition and erosion in individual reaches. The most change occurred in the Hungry Hollow Reach, where 374,786 tons of sediment was deposited and 686,781 tons of sediment was eroded. The Dunnigan Hills and Rio Jesus Maria reaches had the least topographic change in Water Year 2019.
Because Water Year 2019 continued the channel change and sediment transport conditions last observed in Water Year 2017, the recommendations developed by the Cache Creek TAC did not change substantially from recommendations made in 2017 or 2018. While some areas that experienced erosion or scour in 2017 continued to stabilize through vegetation growth and sediment deposition between 2018 and 2019, many areas continued to experience channel aggradation that forces migration of the active channel and, in some locations, bank erosion at or near program boundaries. Because two of the wettest years on Cache Creek over the last fifteen year occurred in 2017 and 2019, it is an ideal time for the CCRMP to implement as many recommendations as possible during Water Year 2020.
Biological Resource Findings
The condition of biological resources in 2019 was surprisingly similar to conditions observed in 2018. Native woody and herbaceous vegetation were again observed to be re-establishing in many locations despite the 2018–2019 winter season high flows that were assumed to have had a negative impact. Only minor additional erosion and vegetation loss resulting from these flows were observed. Although some formerly vegetated areas that were scoured during the 2016–2017 winter season high flows have yet to recover, other areas are now densely vegetated. Increasing native vegetation was again observed to be creating potentially adverse conditions in some locations; however, no actions are yet required other than continued annual monitoring.
Invasive species are still widespread in many locations along lower Cache Creek, although the intensive treatment of arundo, ravennagrass, and tamarisk that has occurred since 2006 with funding from the Wildlife Conservation Board has greatly reduced the extent of these three species. As in 2018, arundo and tamarisk were observed to be re-establishing and spreading in many locations during the 2019 Creek Walk. Similar to native vegetation, 2018–2019 winter season high flows did not have the anticipated negative impact on arundo and tamarisk within the channel, and limiting further re-establishment and spread of these species should be a top priority. Many additional invasive species (e.g., Himalayan blackberry, perennial pepperweed, and tree tobacco) remain common along lower Cache Creek and should be prioritized for treatment and monitoring. Following the additional of canary grass and purple starthistle to the CCRMP priority invasive species list in 2018, 2019 Creek Walk observations led to the recommendation that invasive primrose also be added to the priority list. After treatment of invasive species, native woody and herbaceous species should be planted whenever possible to enhance habitat and reduce the potential for re-invasion.
Many common and special-status species of wildlife, invertebrates, and fish were again observed by the Cache Creek TAC, County and Cache Creek Conservancy staff, and volunteer observers during the 2019 Creek Walk. Swainson’s hawks (State threatened) were observed in all seven reaches, and a bald eagle (State endangered) was observed above the Capay Dam. Numerous potential colonies of riparian bank swallows (State threatened) were also observed although the juvenile birds had fledged earlier in the year. Western pond turtles (State species of special concern [SSC]) were observed floating in pools and basking on logs, as in years past, and local landowners reported an American badger (SSC) on their property on the north side of the channel in the Dunnigan Hills reach. Additional species of note included Acorn woodpecker, lesser nighthawk, American kestrel, red-tailed hawk, peregrine falcon, osprey, beaver, bobcat, Mexican free-tailed bats, and non-native wild pigs.
Significant opportunities for habitat enhancement and restoration were again noted in 2019, including the PG&E “Palisades” site (river mile [RM] 26.8), Capay Open Space Park (RM 26.3), the Hayes “Bow-Tie” property (RM 20.0), the Millsap property (RM 18.5), Wild Wings Open Space Park (RM 17.0), the Correll-Rodgers properties (RM 13.7), and the Capay Organic creek frontage (RM 27.9) identified in 2019. Based on 2017 and 2018 Creek Walk observations, the long-term resilience of revegetation and restoration projects within or adjacent to the active channel should be carefully considered prior to implementation, since such projects can be negatively impacted or completely removed by high flows. Passive restoration (e.g., streamflow enhancement) may be a more cost-effective approach for in-channel or near-channel locations subject to high flows.
Summary of 2019 Recommendations
Hydrologic and Water Quality Recommendations
The Cache Creek TAC Hydraulic Engineer recommends the following:
1) Capay Dam – Remedies to prevent future damage of the dam and movement of the dam’s concrete pads into the channel should be undertaken.
2) PG&E Palisades – The erosion control blanket and all associated infrastructure be removed and the palisades either be removed entirely or cut at or below ground level and revegetation/natural stabilization project be implemented. PG&E is working on design plans to implement this.
3) Erosion sites identified (Jensen Bend, Granite Esparto, Esparto Bridge, Woodland Reiff, south bank of RM 23.3, Teichert Esparto, and Payne Property) should continue to be monitored in the future.
4) Longitudinal profiles of water surface elevations should be performed in the future to assist in calibrating the hydraulic model of Cache Creek developed in 2016 and updated in 2018. The Cache Creek TAC Hydraulic Engineer recommends mobilizing for survey for a predicted flow in excess of 30,000 cfs if observed in the winter of 2019-2020.
Geomorphology Recommendations
As in previous years, geomorphology recommendations for Water Year 2019 are in three general categories: monitoring, evaluation, and implementation. Monitoring is recommended at multiple sites including RM 28.3 (near Capay Dam), RM 26.7, RM 20.8 (near CEMEX), RM 18.8, RM 18.2 (near Moore’s Siphon), RM 17.8, RM 15.4 (near Teichert Woodland), and RM 12. Monitoring at these locations should focus on lateral channel migration, sediment deposition, and erosion. The Cache Creek TAC Geomorphologist also recommends the following evaluation and implementation actions:
1) Accelerate voluntary implementation of previously recommended bar skimming projects at RM 24.6 – 25 and RM 20.1 – 20.5.
2) Reinitiate voluntary bar skimming project evaluation at RM 21.6.
3) Evaluate the potential for additional bar skimming at RM 21 and RM 22.
4) Complete removal of the PG&E Palisades infrastructure (RM 26.9) from Cache Creek.
5) Notify bridge owners of scour and deposition at bridge piers and abutments, and continued succession of riparian vegetation upstream and downstream of bridges.
6) Continue detailed monitoring and assessment of channel treatments at locations of 2017 channel migration and erosion (RM 26, 25.5, 23.5, 22, 21.5, and 18).
7) Continue detailed monitoring of fine sediment deposition at Huff’s Corner and complete an evaluation of the need to remove deposited fine sediment.
8) Upon approval of the CCAP Update, assess Channel Form Template (CFT) with respect to 2019 topographic conditions at RM 26.0, RM 25.5, RM 23.5, RM 22, RM 21.8, RM 21.4, RM 18.2, and anywhere else the active channel has migrate near or beyond the CFT. Also complete administrative and/or technical changes to the CFT based on the results of this assessment.
9) Yolo County, Cache Creek TAC, Cache Creek Conservancy, Yolo County Resources Conservation District, and Yolo County Flood Control and Water Conservation District should work together to develop a comprehensive invasive species removal, ecosystem restoration, flood management and water supply bundle of projects based on prior Cache Creek TAC recommendations and submit additional Proposition 1 (and other) grant proposals to fund such projects in Water Year 2020.
Biological Resource Recommendations
Recommendations regarding biological resources are grouped into four general categories: native vegetation monitoring and management (Section 5.1.5), habitat restoration (Section 5.2.3), invasive species monitoring and management (Section 5.3.2), and special-status species (Section 5.4.2).
1) Recommendations regarding native vegetation focus on monitoring approaches intended to understand changes in native vegetation, as well as management actions required (if any) to maintain desirable flow conditions.
2) Recommendations regarding habitat restoration highlight high-priority potential projects, the importance of including native understory species, the need for post-implementation monitoring, the importance of planting native species on invasive species treatment sites, and the potential for increased surface flows and strategic channel maintenance projects to accelerate native habitat recovery.
3) Recommendations regarding invasive species monitoring and management include expanding the list of priority species and the areas in which treatments are implemented, the importance of a formal monitoring program to track invasive species, the need to remove treated biomass from the CCRMP area, the importance of planting native species on invasive species treatment sites, and the ongoing need to leverage invasive species treatment within the CCRMP area to support additional mapping and treatment upstream of Capay Dam.
4) Recommendations regarding special-status species focus on the need for additional monitoring and documentation of both rare and common species, documentation of observations, and the potential for increased surface flows to benefit Western pond turtles and other native species.
Program Highlights
The following noteworthy events occurred during the 2019 Water Year:
Three public Cache Creek Technical Advisory Committee (TAC) meetings were held during Water Year 2019: April 15, 2019, July 17-19 (Creek Walk), and September 5, 2019. These meetings were attended by Cache Creek TAC members, County staff, members of various partner agencies, program stakeholders, and the public.
The Cache Creek TAC conducted its 2019 Creek Walk on July 17-19, 2019. The Creek Walk is the annual physical inspection of the creek with the main purpose of documenting channel conditions, as required by the CCIP. The entire length of the CCRMP boundary is covered over three days. Joining the Cache Creek TAC on this year’s Creek Walk was County staff, representatives from the gravel mining industry, program stakeholders, and members of the public. Observations made by the Cache Creek TAC during 2019 Creek Walk are provided as Appendix C of the 2019 Annual Report. A compilation of miscellaneous photographs captured during the 2019 Creek Walk is provided as Appendix D of the 2019 Annual Report.
In Fall 2018, the fourth year of the required five years of mercury sampling in off-channel mining wet pits (Section 10-5.517, OCMP) was conducted, utilizing the services of Dr. Darrel Slotton. The Year #5 sampling event is scheduled to take place in Fall 2019. The reports for the first three years of sampling (2015, 2016, and 2017) are posted on the Natural Resources webpage. The Year #4 (2018) report is currently being reviewed by County staff.
There was one surface water quality sampling event this Water Year, which occurred on January 10, 2019. The samples from this event were analyzed for a suite of water quality constituents. A detailed discussion of these results is included in Chapter 3 of the 2019 Annual Report.
On May 10, 2019, the Draft Environmental Impact Report for the Cache Creek Area Plan Update was released for a 45-day public comment period. On August 20, 2019, the Final Environmental Impact Report was released. Staff brought the CCAP Update package before the Planning Commission on November 14, 2019, and recommended the Commission make a recommendation to the Board of Supervisors to certify the EIR and adopt the CCAP Update package. The Planning Commission voted unanimously (7-0-0) to support staff’s recommended action. On December 17, 2019, the Board of Supervisors unanimously voted (5-0-0) to certify the EIR and adopt the CCAP Update package.
On April 9, 2019, the Yolo County Board of Supervisors approved Staff’s recommendation to receive and file the Cache Creek Parkway Plan Open Space Inventory and Baseline Improvements document and its associated Financial Feasibility Study (Minute Order No. 19-59). The Baseline Inventory document contains a map and profile of each of the 17 properties and two bridge structures that are already a part of, or negotiated to become, a part of the CCAP open space system, based on executed development agreements and/or other prior negotiations relevant to each site. Also included is descriptive information about each property, along with a brief property history, details relating to access and dedication terms, relevant legal documents and technical studies, existing or approved improvements, and known opportunities and constraints related to existing conditions or known or approved future conditions. The associated financial feasibility analysis concludes that project revenues will be adequate to fund the Cache Creek Parkway at baseline conditions. In the same action, the Board of Supervisors directed Staff to revise and circulate the Cache Creek Area Plan Parkway Master Plan and Vision document and Parkway Master Plan Financial Feasibility Study. The Master Plan contains an overall vision for future trail connections, identification of gaps and recommendations for future acquisitions, site-specific recreational and open-space opportunities, and recommended future improvements, consistent with the goals and aspirations of the CCAP. Staff has received these documents in draft form and are currently reviewing them. Additionally, the Board directed staff to conduct public outreach on these documents. The public outreach schedule is currently under development and will occur in early 2020.
On April 9, 2019, the Yolo County Board of Supervisors approved a Flood System Repair Project funding agreement, and associated resolutions, with the State Department of Water Resources to receive $2,418,250 in funding for the repair and rehabilitation of the Huff’s Corner segment of the Cache Creek levee system (Minute Order No. 19-60). The work plan subject to this agreement includes two major projects: 1) a full raise of the Huff’s Corner levee segment; and 2) a reconfiguration of the Cache Creek channel adjacent to the levee segment to control bank erosion. The project is estimated to be complete in Summer 2021.
In April 2019, the Yolo County Archives completed a digitization project of all historical CCAP program files. The project lasted six months and involved going through the 90+ boxes the program has accumulated over the last 20 years and scanning and sorting relevant files. The Natural Resources Division is greatly appreciative for the Archives team’s hard work.
In September 2019, the County received notice that the planning grant application that was submitted to California State Parks OHV Grants and Cooperative Agreements Program was funded to the amount of $152,310. The application involves the preparation of a market analysis to ascertain if there is enough community and stakeholder support for OHV opportunities in the County. Assuming there is demand and support for these opportunities, the County will prepare a feasibility study to examine two different scenarios: (1) improving access to exhibit OHV trail riding opportunities within the unincorporated County; and (2) creating a small-to-medium sized OHV park in the unincorporated County. The County has executed a project agreement with the State and has released a Request for Proposals for consultant services. The project is expected to officially kick-off in early 2020.
In September 2019, the 2019 Lower Cache Creek aerial survey project was completed. The program requires that an aerial survey of the creek occur every five years, or after a major creek event defined as 20,000 cubic feet per second (cfs) or greater at the Yolo gage. In this instance, the latter of the two thresholds was triggered. |