ITEM: INFORMATIONAL ITEMS/STAFF REPORTS
29. QUARTERLY IRRIGATION PROGRAM AND RIPARIAN PROJECTS REPORT
Program/Line Item No.: N/A
Staff Contact: Thomas Christensen Cost Estimate: N/A
General Counsel Approval: N/A
Committee Recommendation: 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 June: DeDampierre, Trail and Saddle, Scarlett, Begonia, Schulte South, Schulte Bridge, Schulte, All Saints, and Valley Hills.
Water Use in Acre-Feet (AF)
April - June 2004 2.50
MONITORING OF RIPARIAN VEGETATION: During the months of May and June 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 riparian vegetation is below threshold stress levels. 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 June 2004 are as follows:
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. Irrigation System Tune Up: District staff (Christensen, Lyons, and Bekker) tuned up nine of the District's irrigation systems by flushing lines, repairing leaks, and replacing over 700 clogged emitters. Irrigation systems are run to offset impacts to riparian vegetation associated with groundwater extraction and to help new restoration plantings become established.
2. Annual Carmel River Inspections: District staff began the annual inspections of the Carmel River from the upstream end of the lagoon at River Mile (RM) 0.5 to Camp Steffani at RM 15.5. Staff members responsible for vegetation management and erosion prevention annually walk the entire river to observe and record erosion damage, conditions that could cause erosion (e.g., in-channel vegetation or debris), riparian ordinance infractions, presence of deleterious material, and the overall condition of the riparian corridor. Staff also uses these inspections to document existing river restoration projects and compliance with previously issued River Work Permits.
Staff has completed an inspection from Camp Steffani to the west end of West Garzas Road. Several riparian ordinance infractions were noted, and staff plans to follow up on these with letters to individual property owners. Overall, this section of the river appears to be healthy. However, staff noted several locations where vegetation encroachment into the center of the channel appears to be extensive enough to increase the potential for bank erosion during high winter flows. Additional work to document these sites and develop a modification strategy is under way.
3. Irrigation System Expansion at Cal-Am's Rancho Cañada Well: On June 23, 2004, District staff (Christensen, Bekker, and Lyons) expanded the irrigation system on the south bank of the Carmel River opposite Cal-Am's Cañada Well. This system is designed to offset impacts to riparian vegetation associated with an increase in pumping capacity of the well from approximately 1,500 gallons per minute (gpm) to 2,500 gpm. Rancho Cañada Golf Club is currently irrigating the north side of the river in the vicinity of the well.
29-A Average Dawn Leaf Water Potential
29-B Depth to Groundwater