26. 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 in calendar year 2003 began in May at nine Monterey Peninsula Water Management District (District) riparian habitat restoration sites and ended in October. The following irrigation systems were operated May through October: DeDampierre, Trail and Saddle, Scarlett, Begonia, Schulte South, Schulte Bridge, Schulte, All Saints, and Valley Hills. Quarterly use for the year to date is as follows:
Water Use in Acre-Feet (AF)
April - June 2003 1.38
MONITORING OF RIPARIAN VEGETATION: During the months of May through October 2003, staff took weekly measurements of dawn 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 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 installed 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.
Monitoring results for the 2003 monitoring season show that non-irrigated sample willows and cottonwoods at Valley Hills and Schulte are severely stressed. Willows and cottonwoods at Rancho Cañada and San Carlos were below threshold values. 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 26-A show impacts to water table elevations and riparian moisture stress in selected restoration sites in Lower Carmel Valley. As of August 4, 2003 stream flow ceased in the Rancho Cañada area. Stream flow returned to the Rancho Cañada area on December 29, 2003. Starting November 1, 2003, monitoring of riparian vegetation is suspended until May of 2004 because there is sufficient soil moisture for maintenance and growth of the vegetation.
The types of monitoring measurements made during May through October 2003 are as follows:
Dawn leaf water potential (See Exhibit 26-A for trends.)
Soil moisture (tensiometers)
Groundwater levels (monitoring wells) (See Exhibit 26-B for trends.)
Groundwater pumping (production wells)
OTHER TASKS PERFORMED SINCE OCTOBER’S 2003 REPORT:
1. Training Assistance to Carmel River Watershed Conservancy (CRWC): On Saturday October 11, 2003, District Staff (Larry Hampson and Thomas Christensen) participated in a CRWC workshop to train volunteers in procedures for conducting a watershed assessment. The CRWC has agreed to compensate the District for staff's time in the workshop. At the October 30, 2003 meeting, the Board approved a contract between the District and CRWC to provide additional services to assist in the watershed assessment. For all work performed under this contract, the District would be compensated for staff time.
2. In-Channel Vegetation Management: On October 28, 2003, District staff (Christensen, Hampson, Lyons, and Bekker) made modifications to two black cottonwoods that had fallen across the Carmel River channel downstream of Highway One near the Carmel Area Wastewater District treatment plant. The crowns of these trees were removed to prevent erosion associated with diversion of high flows and collection of debris.
3. Carmel River Watershed Assessment: On Saturday, November 22, 2003, Thomas Christensen and Larry Hampson conducted a workshop on the "Proper Functioning Condition" method for assessing the health of riparian corridors. The all-day workshop was being held at the Carmel Middle School in cooperation with the Carmel River Watershed Council (CRWC) and followed the same format as the previous workshop given in October. The methodology will be used in the watershed assessment to be carried out in 2004 under the sponsorship of the CRWC.
4. Large Wood Habitat Structures Monitoring: District staff (Christensen and Hampson) surveyed river cross-sections in the area of the large wood habitat structures at the DeDampierre Ball Fields near Carmel Valley Village. Cross-sections help track pool formation and river bed change associated with the large wood installation, and is surveyed on an annual basis.