Meeting Date:

January 25, 2007





David A.  Berger,


2-6-2 Integrated Regional


General Manager


Water Management Plan




(Prop 50 Grant)

Prepared By:

Larry Hampson

Line Item No.:

Acct. No. 7855.05




Cost Estimate:

$ 61,000.00

General Counsel Approval:  Approved

Committee Recommendation:  The Administrative Committee reviewed this item on January 18, 2007 and recommended approval.

CEQA Compliance:  N/A


SUMMARY:  The District and the Monterey County Water Resources Agency (MCWRA) have joint responsibility for managing the water resources of the Canyon Del Rey Creek watershed, which straddles Highway 68 between the ocean and Laguna Seca.  In 1977, MCWRA completed the Canyon Del Rey Watershed portion of the Monterey County Master Drainage Plan (CDRW Master Drainage Plan) and began collecting funds from development projects to carry out future watershed tasks.  Since 1977, significant changes have occurred in the watershed including the development of residential and commercial property adjacent to Highways 68 and 218 and some drainage improvements have been completed.  However, high flows in 1995 and 1998 highlighted significant erosion, siltation, and flood problems throughout Canyon Del Rey Creek.  The proposed update would evaluate drainage facilities in and near the creek.


Groundwater extraction in the watershed, which is part of the Seaside Groundwater Basin, has increased significantly since 1988. In 2006, the groundwater was adjudicated and the Court ordered that the supply and demand within the basin be brought into balance. Deep percolation of rainfall and applied irrigation water are the largest sources of groundwater recharge in the area.   In normal years, streamflow is generally a small percentage of rainfall and, except at the Pasadera development, stormwater capture is not generally used to supplement groundwater recharge.  The proposed update to the CDRW Master Drainage Plan would investigate the feasibility of combining stormwater capture and groundwater recharge in the watershed.

MCWRA would like to use a portion of the funds collected since 1977 to update the CDRW Master Drainage Plan.  Attached as Exhibit 6-A is a draft agreement defining how MCWRA and MPWMD would cooperate to contract for consultant services, complete the update, and administer the funds.  Attached as Exhibit 6-B is the proposed scope of work, estimated cost, and schedule. 


The proposed project is to prepare a summary update of the CDRW Master Drainage Plan to identify areas of constriction, erosion or impediment to flow and to provide direction for future structure upgrades in the watershed.  To complete the update to the CDRW Master Drainage Plan, District staff proposes two linked actions:


A) MPWMD will enter into an agreement with MCWRA to reimburse MPWMD for up to $61,000, which would include the estimated cost of $54,990 for consulting services and an additional $6,010 for contingencies.  The work would take approximately 18 weeks to complete (please note that if this item is approved, the schedule in Exhibit 6-B will be updated prior to beginning work); and


B) After executing a reimbursement agreement with MCWRA, the existing agreement between MPWMD and RMC for completing the IRWM Plan will be amended to include work to update the CDRW Master Drainage Plan.


When completed, this study and recommended actions would be incorporated into the Proposition 50-funded Integrated Regional Water Management Plan (IRWMP, or IRWM Plan) currently being developed for this Region under the District’s guidance and with the services of RMC Water and Environment (RMC).




Authorize the General Manager to:


A)    Enter into an agreement with the Monterey County Water Resources Agency to reimburse the Monterey Peninsula Water Management District for up to $61,000 for costs associated with completing an update to the Canyon Del Rey Watershed portion of the Monterey County Master Drainage Plan.

B)     Amend the current agreement with RMC Water and Environment and increase the not-to-exceed amount by $61,000 from $165,000 to a total of $226,000.


BACKGROUND: Canyon Del Rey Creek is an ephemeral stream that drains an area of 16.8 square miles (approximately 10,750 acres) along Highways 68 and 218 from upstream of Laguna Seca west into Monterey Bay (see map, Exhibit 6-C).  The watershed includes portions of Seaside, Del Rey Oaks, Monterey, and unincorporated Monterey County. The Monterey County Flood Control and Water Conservation District (since renamed as the Monterey County Water Resources Agency) completed a Master Drainage Plan for the Canyon Del Rey watershed in June 1977.  Improvements recommended in that study were proposed to reduce flooding damage to structures as a result of the expected 100-year return period flood.  Additional analyses and recommendations were made in the 1977 study to pass the expected 10-year storm at road and highway drainage facilities.  Another recommendation in that plan was “… periodic updating of the Master Plan to reflect actual conditions, as development occurs, is strongly recommended as the basis on which to provide for future conditions.”

To fund needed improvements, the 1977 study recommended both property tax assessments and fees for new developments.  However, with the passage of Proposition 13 in June 1978, property taxes were capped and only a small development fee was initiated.  As of mid-2006, the fund had accumulated approximately $66,000.  In the interim, some improvements and erosion prevention measures on individual parcels developed since that time have been completed (but not with funds from the development fee).


Geologic evidence and soil moisture budget analyses both indicate the presence of a shallow alluvial aquifer system that sustains wetlands and phreatophytic vegetation and also supports baseflow in Canyon Del Rey in wet years[1].  Hydrogeologic conditions along Canyon Del Rey suggest that it is not a significant source of groundwater recharge and runoff in the creek normally represents a small fraction of the annual rainfall.  However, some recharge of the groundwater is thought to occur along the valley floor through leaks in the shallow aquifer. 


Groundwater level data collected between 1989 and 2001 showed a widespread declining trend in groundwater levels.  In 2006, groundwater in the basin was adjudicated and the Court ordered that the supply and demand be brought into balance[2].  However, high flows during the extremely wet years of 1995 and 1998 exposed several drainage problems and confirmed some of the predictions made in the 1977 study, especially concerning headcutting in the creek, transportation of silt from the headwater areas, and culvert sedimentation of road drainage facilities. 


The proposed project is to prepare a summary update of the CDRW Master Drainage Plan to identify areas of constriction, erosion or impediment to flow and to provide direction for future structure upgrades in the watershed.  For the update, the area of initial concern begins near the north end of Silver Cloud Court near the intersection of Highway 68 and York Road in Monterey County. The stream channel currently suffers from bank instability, headcutting, and erosion problems along adjacent private properties due to a variety of factors such as increased stream flows during rain events, changes in sediment supply in the watershed, and creekside development. Recent conditions in the watershed include:


1.         The construction of a larger culvert at Boot Road. The previous smaller culvert detained water and reduced peak flows downstream. With the larger culvert, high flow rates have been observed, which may exacerbate erosion processes downstream.

2.         Several residential structures along the creek have been threatened by streambank loss.  Local property owners want a solution to this problem and believe that increased development within the watershed has contributed to bank erosion and has also contributed to a decline in the water level of the aquifer supporting the Bishop unit of the California American Water Company.  There are several detention, tertiary, and retention ponds currently operated within the watershed that may affect runoff quantity and aquifer recharge characteristics.

3.                  The failure of a major spillway on a detention pond near the entrance of the Pasadera development that has not been corrected.


The update to the study is a cooperative effort between the Monterey County Water Resources Agency (MCWRA) and the Monterey Peninsula Water Management District (MPWMD).  MCWRA is providing funding and technical expertise while MPWMD will be the contracting agency and also provide technical expertise.  All work products described in this scope will be jointly reviewed by MCWRA and MPWMD staff.


IMPACT TO STAFF/RESOURCES: An extensive update of the existing Canyon Del Rey Watershed Master Drainage Plan was not proposed in the scope of work for the Integrated Regional Water Management Plan for the Region.  However, an investigation of infrastructure and drainage problems was included in the original scope of the IRWM Plan.  A more thorough update of the CDRW Master Drainage Plan may require additional review by staff, but is within the general scope of work that was expected for development of the IRWM Plan.  Funds were not budgeted for this expanded scope of work in the District’s current agreement with RMC.  However, District expenditures for this work will be reimbursed in accordance with the proposed reimbursement agreement between MPWMD and MCWRA.


At their regular meeting on August 21, 2006, the MPWMD Board of Directors (Board) authorized staff to amend the existing Agreement for Services between MPWMD and RMC Water and Environment (RMC) for completing an IRWM Plan for the Monterey Peninsula, Carmel Bay and South Monterey Bay.  The Board approved an amendment for a not-to-exceed amount of $165,581.  If this item is approved, the not-to-exceed amount for the RMC agreement would be increased an additional $61,000 from $165,581 to a total of $226,581.


The staff person responsible for administration of the agreements and supervision of the work is Larry Hampson, MPWMD Water Resources Engineer.



6-A      Draft Agreement between MCWRA and MPWMD

6-B      Proposed Scope of Work, Estimated Cost, and Schedule

6-C      Canyon Del Rey Watershed Map





[1] See “Laguna Seca Subarea Phase III Hydrogeologic Update,” prepared for the Monterey Peninsula Water Management District by Eugene B. Yates, Martin B. Feeney, and Lewis L. Rosenberg, November 2003.

[2] See California-American Water Company v. City of Seaside et. al., Monterey County Superior Court Case No. M66343, Final Decision.