Receive and file the 2021 Cache Creek Annual Status Report. (No general fund impact) (Perez/Liebler)

1. Receive and file the 2021 Cache Creek Annual Status Report;
    
2. Direct staff to submit the finalized report with the Chief Clerk of the California State Assembly by February 15, 2022; and
    
3. Direct staff to work with the Cache Creek Technical Advisory Committee to integrate and prioritize recommendations contained in the 2021 Cache Creek Annual Status Report into the FY 21/22 and 22/23 budgets, as appropriate.

Sustainable Environment

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 are protection of groundwater, preservation of agriculture, restoration of Cache Creek, and regulation of commercial mining. 

The CCRMP (adopted August 20, 1996, amended August 15, 2002, and December 17, 2019) is an adaptive watershed restoration and management plan.  It eliminated in-channel commercial mining and established an improvement program for implementing on-going projects related to channel stability and restoration of habitat within and along the creek.  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, revegetation, and habitat restoration. 

The CCIP is overseen by the Cache Creek Technical Advisory Committee (Cache Creek TAC), which is a three-person interdisciplinary group comprised of a hydraulic engineer, a fluvial geomorphologist, and a riparian biologist.  The Cache Creek TAC was established to provide scientific and technical review and oversight for all projects conducted under the CCIP, as well as collect and evaluate scientific data on hydrologic, hydraulic, sediment transport, and biological conditions within the CCRMP area.  The Cache Creek TAC is currently staffed (via contracts held by the County) by Paul Frank, P.E., CED (Hydraulic Engineer), Mark Tompkins, P.E., Ph.D (Fluvial Geomorphologist), and Andrew Rayburn, Ph.D (Riparian Biologist).

Section 2.2 of the CCIP requires that the Cache Creek TAC produce an annual status report each year for the Yolo County Board of Supervisors.  The report is intended to: 1) document the previous year's monitoring results, field observations, and completed in-channel restoration or stabilization projects; 2) provide analysis of data and trends; and 3) identify recommendations and projects to be implemented the following year.  This report represents a critical component of the adaptive management of Lower Cache Creek. 

The annual report subject to this staff report is for the 2021 Water Year which covers the period of October 1, 2020 to September 30, 2021 (Attachment A).  

SUMMARY OF FINDINGS

Hydrologic and Water Quality Findings

The 2021 Water Year was a dry year for Cache Creek and the Sacramento River Valley.  Drought conditions persisted and no peak flow was recorded at the Yolo USGS streamflow gage.  Due to the lack of sufficient flows, in-channel water quality sampling did not occur during the 2021 Water Year.

Geomorphology Findings

Since there was no surface flow at the Yolo gage, the threshold required for significant sediment transport and channel change was not met.  These no flow conditions contributed to the lowest delivery and transport of sediment to and through the CCRMP area over the last 17 years.  As a result, the only measurable channel change in Cache Creek in Water Year 2021 was the continued persistence and expansion of riparian vegetation in and along the channel that established after the extremely wet Water Year 2019.

Biological Resources Findings

The condition of biological resources in 2021 was generally similar to conditions observed in 2020, although drought-stressed vegetation was observed in several new locations. Continued growth of native and non-native woody and herbaceous vegetation was observed in some locations observed during the 2021 Creek Walk, as expected given the lack of significant scouring flows during the 2020–2021 winter season.  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.

Non-native and invasive plant species remain widespread along Lower Cache Creek, and continue to be one of greatest constraints to further recovery of native habitat. As in recent years, arundo, tamarisk, Ravenna grass, and other non-native species were frequently observed and are re-establishing and potentially spreading in some locations.  Many additional non-native and 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.  After treatment of non-native and 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, Cache Creek Conservancy staff, and volunteer observers during the 2021 Creek Walk.  Swainson’s hawks (State threatened) were observed in all seven reaches, and Western pond turtles (State species of special concern) were observed in the Dunnigan Hills reach.  An off-channel colony of riparian bank swallows (State threatened) were reported by Teichert Esparto staff in the Madison reach, and Sacramento roach (State fish species of special concern) was observed in a pool in the Guesisosi reach. A total of 63 unique bird species were observed in 2021 including red-tailed hawk, bald eagle, American kestrel, acorn woodpecker, Bullock’s oriole, song sparrow, marsh wren, and wood duck.  Other wildlife species observed included Columbian black-tailed deer, black-tailed jackrabbit, bobcat, Western whiptail, and non-native common carp. Several dead beaver were also observed in reaches of Cache Creek that are typically flowing in early summer, but that were dry in at the time of the 2021 Creek Walk.

Significant opportunities for habitat enhancement and restoration are essentially unchanged from 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), the Moore Siphon repair site (RM 18.0), Wild Wings Open Space Park (RM 17.0), the Correll-Rodgers properties (RM 13.7), the Capay Organic creek frontage (RM 27.9) identified in 2019, and off-channel pits in the Dunnigan and Hoppin reaches.  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 and invasive species treatment) may be a more cost-effective approach for in-channel or near-channel locations subject to high flows.

SUMMARY OF 2021 RECOMMENDATIONS

Hydrologic and Water Quality Recommendations

The Cache Creek TAC Hydraulic Engineer recommends the following:

• Capay Dam – Remedies to prevent future damage of the dam and movement of the dam’s concrete pads into the channel should be undertaken.  Additionally, erosion behind the recent emergency bank stabilization wall should be investigated and addressed. 
• PG&E Palisades – The erosion control blanket and all associated infrastructure should be removed.  As of 2021, PG&E is working on implementing the removal with construction expected in 2022.
• Erosion sites identified (Jensen Bend, Granite Esparto, Esparto Bridge, south bank of RM 23.3, Teichert Esparto, Payne Property, and Woodland Reiff) should continue to be monitored in the future. 
• Consideration should be given to removal of bank protection weirs particularly downstream of the Esparto Bridge.  These weirs are eroding, are used by illicit off-highway vehicle use, and could be replaced by more modern approaches to bank stabilization. 
• Review the program's in-channel water quality sampling program in light of variability in Cache Creek flows and make changes, if needed.

Geomorphology Recommendations

As in previous years, the TAC Geomorphologist's recommendations for Water Year 2021 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, 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.

Evaluation and implementation actions continue to be recommended for the following:

• Accelerate voluntary implementation of previously recommended bar skimming projects at RM 24.6 – 25 and RM 20.1 – 20.5. 
• Reinitiate voluntary bar skimming project evaluation at RM 21.6.
• Evaluate the potential for additional bar skimming at RM 21 and RM 22.
• Complete removal of the PG&E Palisades infrastructure (RM 26.9) from Cache Creek.
• Notify bridge owners of scour and deposition at bridge piers and abutments, and continued succession of riparian vegetation upstream and downstream of bridges.
• 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).
• Continue detailed monitoring of fine sediment deposition at Huff’s Corner and complete an evaluation of the need to remove deposited fine sediment.
• Following the 2019 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 migrated near or beyond the CFT.  Also, complete administrative and/or technical changes to the CFT based on the results of this assessment. 
• 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 2022.

Biological Resources Recommendations

Recommendations regarding biological resources are grouped into four general categories: native vegetation monitoring and management (Annual Report Section 5.1.5), habitat restoration (Annual Report Section 5.2.3), invasive species monitoring and management (Annual Report Section 5.3.2), and special-status species (Annual Report Section 5.4.2).

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.

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. A new recommendation is made regarding opportunities to incorporate native plant species of cultural importance to the Yocha Dehe Wintun Nation into revegetation and restoration projects.

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.

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 plant and wildlife species.

The implementation of the CCAP program includes coordination and collaboration with a multitude of stakeholders including landowners, the aggregate producers, the Cache Creek Conservancy, the Yolo County Flood Control and Water Conservation District, the Yolo Habitat Conservancy, the Yolo County Resource Conservation District, and state and federal agencies.