ITEM:

INFORMATIONAL ITEM/STAFF REPORT

 

24.

QUARTERLY CARMEL RIVER RIPARIAN CORRIDOR MANAGEMENT PROGRAM REPORT

 

Meeting Date:

October 19, 2020

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 season at seven Monterey Peninsula Water Management District (District) riparian habitat restoration sites.  The following irrigation systems were in use May through September: Sleepy Hollow, deDampierre, Trail and Saddle Club, Begonia, Schulte, Valley Hills, and San Carlos.

 

            Water Use in Acre-Feet 2020 (AF)

            (preliminary values subject to revision)

            January - March          0.22 AF

            April - June                 0.63

            July – September        1.15

            Year-to-date                2.00 AF

 

MONITORING OF RIPARIAN VEGETATION:   Starting in June 2020, staff recorded monthly 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 monthly 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 24-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 2020 monitoring season to date show that riparian vegetation is below threshold moisture stress levels. The graph in Exhibit 24-A shows average canopy ratings for willows and cottonwoods in selected restoration sites in lower Carmel Valley.  The graph in Exhibit 24-B shows impacts to water table elevations.   The types of monitoring measurements made during June through September are as follows:

 

            Monitoring Measurement                                       

            Canopy ratings                                                (See Exhibit 24-A for trends.)          

            Groundwater levels (monitoring wells)          (See Exhibit 24-B for trends.)          

            Groundwater pumping (production wells)

 

OTHER TASKS PERFORMED SINCE THE JULY 2020 QUARTERLY REPORT:

 


1.                  Rancho San Carlos Bank Stabilization Project:  The District continues to irrigate the Rancho San Carlos Bank Stabilization Project just downstream of Rancho San Carlos Road Bridge. District staff have noticed vigorous growth of willows and cottonwood trees this summer, which will help stabilize this reach of the river. This area experienced significant erosion in the winter of 2016-2017.

 

EXHIBITS

24-A    Average Willow and Cottonwood Canopy Rating

24-B    Depth to Groundwater

                       

 

 

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