ITEM:

INFORMATIONAL ITEMS/STAFF REPORTS

 

28.

QUARTERLY IRRIGATION PROGRAM AND RIPARIAN PROJECTS REPORT

 

Meeting Date:

July 21, 2008

Budgeted

N/A

 

From:

Darby Fuerst,

Program/

N/A

 

General Manager

Line Item No.:

 

Prepared By:

Thomas Christensen

Cost Estimate:

N/A

 

General Counsel Approval:  N/A

Committee Recommendation:  N/A

CEQA Compliance:  N/A

 

IRRIGATION OF RIPARIAN VEGETATION: The supplemental watering of riparian restoration plantings resumed in March of 2008 at ten Monterey Peninsula Water Management District (District) riparian habitat restoration sites.  The following irrigation systems were in use March through June: De Dampierre, Trail and Saddle Club, Scarlett, Begonia, Schulte South, Schulte Bridge, Schulte, All Saints, Valley Hills, and San Carlos at Dow Property.

 

            Water Use in Acre-Feet (AF)

            (preliminary values subject to revision)

           

            January - March 2008   0.01 AF

            April - June 2008           2.19

            Year-to-date                  2.20 AF

 

MONITORING OF RIPARIAN VEGETATION:   During May and June 2008, staff recorded weekly 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 every week for canopy ratings based on a scale from one to eleven. This scale evaluates characteristics such as yellowing leaves and percentages of defoliation (see scale on Exhibit 28-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.  Soil moisture measurements are conducted at three of these sites (San Carlos, Valley Hills, and Schulte) using tensiometers.  Soil moisture values are measured at seven stations with 18-inch and 36-inch tensiometers in the soil column.  Combined with monthly readings from the District’s array of monitoring wells and pumping records for large-capacity Carmel Valley wells in the CAW system, the District’s monitoring provides insight into the status of soil moisture through the riparian corridor.

 

Current monitoring results for the 2008 monitoring season to date show that riparian vegetation is below threshold stress levels.  Some signs of yellowing are occurring but the overall riparian corridor still shows obviously vigorous trees. The graphs in Exhibit 28-A and 28-B show average canopy ratings for willows and cottonwoods in selected restoration sites in the lower Carmel Valley and impacts to water table elevations.

 

The types of monitoring measurements made during May through June 2008 are as follows:

 

            Monitoring Measurement                                        

 

            Canopy Ratings                                                (See Exhibit 28-A for trends.) 

            Soil moisture (tensiometers)                                         

            Groundwater levels (monitoring wells)   (See Exhibit 28-B for trends.) 

            Groundwater pumping (production wells)                     

           

 

 

OTHER TASKS PERFORMED SINCE MARCH 2008 REPORT:

 

1.         Annual Carmel River Inspections: During the month of May, District staff inspected the Carmel River from Camp Steffani (River Mile 15.5) to the Carmel River Lagoon (River Mile 0.0). Annual inspections help determine the scope of work for vegetation management activities typically conducted in the fall in preparation for high winter flows, and for addressing new erosion problems and riparian ordinance violations.

 

2.         Carmel River Vegetation Management Project Notification:  On June 3, 2008, District staff sent formal notification to the U.S. Army Corps of Engineers, National Marine Fisheries Service, U.S. Fish and Wildlife Service, and Monterey County of the District’s proposal to conduct vegetation management activities at four sites along the Carmel River this summer and fall.  Staff identified these areas during this year’s annual river inspection as being in need of vegetation trimming and/or removal. These activities are covered under the District’s Regional General Permit from the Corps of Engineers. A total of approximately 1,050 lineal feet of stream encompassing a total area of approximately 0.36 acre in the channel bottom will be affected by the project.  The goal of the vegetation management is to reduce the risk of streambank erosion along riverfront properties where vegetation encroachment could potentially divert river flows into the streambanks during high-flow periods.

 

EXHIBITS

28-A    Average Willow and Cottonwood Canopy Rating

28-B    Depth to Groundwater

 

 

 

 

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