ITEM:

INFORMATIONAL ITEM/STAFF REPORT

 

22.

QUARTERLY CARMEL RIVER RIPARIAN CORRIDOR MANAGEMENT PROGRAM REPORT

 

Meeting Date:

October 20, 2025

Budgeted:

N/A

 

From:

Dave Stoldt,

Program/

N/A

 

General Manager

Line Item No.:

 

Prepared By:

Thomas Christensen

Cost Estimate:

N/A

                            

General Counsel Review:  N/A

Committee Recommendation:  N/A

CEQA Compliance:  This action does not constitute a project as defined by the California Environmental Quality Act Guidelines Section 15378.

 

IRRIGATION OF RIPARIAN VEGETATION: The supplemental watering of riparian restoration plantings is currently being carried out for the summer and fall season at seven Monterey Peninsula Water Management District (District) riparian habitat restoration sites. The following irrigation systems were in use April through September: Sleepy Hollow, deDampierre, Trail and Saddle Club, Begonia, Schulte, Valley Hills, and San Carlos.

 

            Water Use in Acre-Feet 2024 (AF)

            (preliminary values subject to revision)

            January - March          0.02 AF

            April - June                 0.31

            July – September        0.89

            Year-to-date                1.22 AF

 

MONITORING OF RIPARIAN VEGETATION:   Starting in July 2025, staff recorded observations of canopy vigor on target willow and cottonwood trees to provide an indication of plant water stress and corresponding soil moisture levels. Four locations (Rancho Cañada, San Carlos, Valley Hills, and Schulte) are monitored for canopy ratings based on a scale from one to ten. This scale evaluates characteristics such as yellowing leaves and percentages of defoliation (see scale on Exhibit 22-A). A total of 12 willows and 12 cottonwoods at these locations provide a data set of established and planted sample trees that are representative of trees in the Carmel River riparian corridor. Combined with monthly readings from the District’s array of monitoring wells and pumping records for large-capacity Carmel Valley wells in the California American Water service area, the District’s monitoring provides insight into the status of soil moisture through the riparian corridor.

 

Current monitoring results for the 2025 monitoring season to date show that riparian vegetation is experiencing little to no moisture stress associated groundwater extraction because of the favorable depth to groundwater and soil moisture. It is important to note that irrigation around municipal wells is carried out to help alleviate impacts from water extraction. The graph in Exhibit 22-A shows average canopy ratings for willows and cottonwoods in selected restoration sites in lower Carmel Valley.  The graph in Exhibit 22-B shows impacts to water table elevations. The types of monitoring measurements made during July through September are as follows:

 

            Monitoring Measurement                                       

            Canopy ratings                                                (See Exhibit 22-A for trends.)          

            Groundwater levels (monitoring wells)          (See Exhibit 22-B for trends.)          

            Groundwater pumping (production wells)

 

OTHER TASKS PERFORMED SINCE THE JULY 2025 QUARTERLY REPORT:

 

1.                  District staff have been carrying out vegetation management along reaches of the Carmel River to prevent debris dams or diversion of high winter flows into vulnerable streambanks. Most of the work includes cutting downed trees into smaller sections so they can safely move through the system during high flows.

 

EXHIBITS

22-A    Average Willow and Cottonwood Canopy Rating

22-B    Depth to Groundwater

                       

 

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