ITEM:

INFORMATIONAL ITEMS/STAFF REPORTS

 

29.

QUARTERLY IRRIGATION PROGRAM AND RIPARIAN PROJECTS REPORT

 

Meeting Date:
October 18, 2004

Budgeted: 

N/A

 

From:

David A. Berger,

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 April of 2004 at nine Monterey Peninsula Water Management District (District) riparian habitat restoration sites.  The following irrigation systems were irrigated April through September:  DeDampierre, Trail and Saddle, Scarlett, Begonia, Schulte South, Schulte Bridge, Schulte, All Saints, Valley Hills, and San Carlos.

 

            Water Use in Acre-Feet (AF)

            January - March 2004              0.00 AF

            April - June 2004                    2.50

            July – September 2004             6.11

            Year-to-date                            8.61 AF

 

MONITORING OF RIPARIAN VEGETATION:  During the months of May through September 2004, staff took weekly measurements of leaf water potential 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 twice a month for pre-dawn leaf water potential.  A total of 14 willows and 13 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 Cal-Am system, the District’s monitoring provides insight into the status of soil moisture through the riparian corridor.

 

Current monitoring results for the 2004 monitoring season to date show that non-irrigated sample cottonwoods and willows at Valley Hills became severely stressed from mid July to late August. Sample trees are not irrigated intentionally to see how they respond in a natural setting with groundwater extraction. However, the projects as a whole are irrigated and riparian vegetation is under threshold values. Willows are considered severely stressed when values are 7.5 bars and above, while cottonwoods are considered severely stressed when values are 10.0 bars and above. 

 

The graphs in Exhibit 29-A show impacts to water table elevations and riparian moisture stress

in selected restoration sites in the lower Carmel Valley. On June 9, 2004, stream flow ceased in the Rancho Cañada area.

 

The types of monitoring measurements made during May through September 2004 are as follows:

 

            Monitoring Measurement                                        

 

            Dawn leaf water potential                                  (See Exhibit 29-A for trends.) 

            Soil moisture (tensiometers)                                         

            Groundwater levels (monitoring wells)   (See Exhibit 29-B for trends.) 

            Groundwater pumping (production wells)                     

           

OTHER TASKS PERFORMED SINCE MARCH 2004 REPORT:

 

1.  San Carlos Irrigation System: On August 4, 2004, District staff completed installation of the temporary irrigation system from San Carlos Road Bridge downstream past Cal-Am's San Carlos Well (1,770 feet). This system is designed to water riparian plants on the bank of the river to help alleviate moisture stress associated with groundwater pumping. This system will be removed after the first significant rains this fall.

 

2.  Carmel River Channel Maintenance:  District staff has identified three areas along the Carmel River in Carmel Valley where vegetation has encroached so far across the channel that it could collect floating debris during high flows and divert flow toward the banks, causing bank erosion.  In mid-July, staff filed for the necessary permits (U.S. Army Corps of Engineers, California Department of Fish and Game (CDFG), and Monterey County).  As of October 5, all permits except for the CDFG Stream Alteration Agreement had been secured.  Because the work must be completed by October 29, in accordance with the Corps permit conditions, District staff has repeatedly urged CDFG to issue their approval.  As discussed at the September 29, 2004 Board Strategic Planning Workshop, staff has prepared letters for the Board Chair and Supervisor Potter to the State Director of CDFG regional urging permit issuance.

 

3.  Annual River Clean Up: On September 22, 2004, District staff (Christensen, Bekker, Lyons, and Hampson) performed a portion of the annual Carmel River clean up from the Highway One Bridge to just upstream of Rancho San Carlos Bridge. So far, 1,120 pounds of car parts, household trash, and 12 tires have been removed from the riverbed.

 

In addition to trash removal, the District also removed a debris pile including two trees over 20 feet in length off of a bridge pier on Rancho Cañada Golf Club property. Each tree was cut into two pieces and then placed downstream of the bridge to create "large wood habitat" in the river channel, consistent with state and federal resource agency requirements.

               

EXHIBITS

29-A    Average Dawn Leaf Water Potential

29-B    Depth to Groundwater

 

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