ITEM:		CONSENT CALENDAR
2.	Consider Expenditure for Carmel River THALWEG PROFILE
Meeting Date:			August 18, 2014	Budgeted:	Yes
From:			David J. Stoldt	Program/	Water Supply
			General Manager	Line Item No.:	1-8-1-B
Prepared By:			Larry Hampson	Cost Estimate:	$25,000
General Counsel Approval: N/A
Committee Recommendation: The Administrative Committee reviewed this item on August 11, 2014 and recommended approval.
CEQA Compliance: N/A

SUMMARY: Staff proposes to contract with Central Coast Surveyors for survey work along up to approximately 15.5 miles of the Carmel River channel between the lagoon and the upstream end of Camp Steffani in Carmel Valley Village. Detailed ground elevation data would be gathered along the profile of the channel at its lowest point (thalweg) as described in Exhibit 2-A, Scope of Work, Budget, and Schedule. Data will be used to maintain a long-term record and to compare with past and future monitoring data. Comparisons of repeated surveys carried out over long periods yields information about the long-term rate of aggradation (sediment build-up in the channel) or degradation (loss of sediment from the channel), and changes in bank storage that affect the capacity of the Carmel Valley Alluvial Aquifer to store water. The river was last profiled in 2007, which showed that three to five feet of degradation had occurred in some reaches in less than 10 years. Anecdotal evidence suggests additional degradation has occurred since 2007.

RECOMMENDATION: Authorize the General Manager to enter into an agreement with Central Coast Surveyors for a not-to-exceed amount of $25,000 to conduct a survey in the Carmel River channel.

DISCUSSION: Most of the riverbed and streambanks along the lower 15.5 miles of the Carmel River in Monterey County, California are composed of loosely consolidated silts, sands, gravels and cobbles. This material makes up the water-bearing alluvium in Carmel Valley that is pumped to supply Cal-Am and non-Cal-Am demand. Because the river channel changes in response to the amount of sediment that flows through it, an important aspect of managing and understanding this portion of the riparian corridor is long-term monitoring and documentation of changes in the elevation of the river bottom.

Gravel mining, main stem reservoirs, and streambank armoring have contributed to a sediment-starved condition in the river channel downstream of Los Padres Dam, which is located at approximately River Mile (RM, measured from the ocean) 25. A chronic lack of sediment from the watershed area above San Clemente Dam for 95 years has been a factor in aquatic habitat degradation, channel incision, streambank instability, infrastructure damage, loss of property, and episodes of bank erosion along the river. In addition, incision and removal of alluvial valley deposits reduces the volume of water that can be retained in storage in the Carmel Valley Alluvial Aquifer.

Survey data will be used by MPWMD staff to adjust Carmel Valley Alluvial Aquifer parameters and to monitor effects to downstream areas from ongoing sediment retention at San Clemente and Los Padres Reservoirs.

Central Coast Surveyors (CCS), a local firm with previous experience in the Carmel River, estimates that the cost per mile of survey work would be approximately $2,800 per mile (see Exhibit 2-B). Staff will work with CCS to identify the most critical reaches to survey.

IMPACT TO STAFF/RESOURCES: Funds for this project are included in the FY 2014-15 budget under Project Expenditures for item 1-8-1-B Carmel Riverbed Topographic Data, Account 35-03-7895.90, $25,000). Staff time will be required to administer the contract. Additional background information is contained in Exhibit 2-A.

EXHIBITS

2-A Scope of Work, Budget and Schedule, Long Profile, Carmel River Channel

2-B August 11, 2014 letter from Central Coast Surveyors (Edson to Hampson)

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