2. CONSIDER AUTHORIZATION OF CONTRACT WITH
CALIFORNIA STATE UNIVERSITY MONTEREY BAY FOR CARMEL RIVER LARGE WOODY DEBRIS
ASSESSMENT
Meeting
Date: August 18, 2003 Budgeted: Yes
Program/Line Item No.: 2-3-3
Staff
Contact: Larry Hampson Cost Estimate: $6,000
General
Counsel Approval: N/A
Committee
Recommendation: The Administrative
Committee reviewed this item on August 12, 2003 and recommended approval.
CEQA
Compliance: N/A
SUMMARY:
District staff proposes to contract with the Watershed Institute of
California State University at Monterey Bay (CSUMB) to complete the inventory
of large wood in the bottom of the Carmel River channel between the Carmel
River lagoon at River Mile 0.5 (RM, measured from the ocean) to San Clemente Dam
at RM 18.6. A partial inventory of large
wood was conducted by CSUMB under contract with the District along eight miles
of the Carmel River during the summer and fall of 2002. (Large wood is defined as pieces of fallen or
cut trees and branches that are six inches in diameter or greater and longer
than five feet.)
Large
woody debris is considered to be an important component of aquatic habitat for
species protected under the Federal Endangered Species Act. The partial inventory of large wood conducted by CSUMB for the District during
the summer and fall of 2002 indicates that large wood is sparse, that less than
10% of the wood surveyed contributes to bank destabilization, and about 25%
enhances aquatic habitat. Staff proposes
to follow up on the previous study by completing a survey of the entire river
bottom. CSUMB would carry out the
survey, create a database, and develop appropriate maps. Two of the CSUMB group who carried out the
2002 survey would be responsible for the 2003 survey. MPWMD staff will provide oversight and
assistance with access.
Completing
an inventory of large wood in the river system should give MPWMD a
comprehensive database that will provide information necessary to assess the
importance and function of large wood in the Carmel River. While large wood is important to instream
habitat, large pieces and amounts of large wood can destabilize streambanks and
damage public and private infrastructure.
Data gathered from this study would be used to develop appropriate
management strategies to comply with Federal Endangered Species Act regulations
concerning protection of this resource, while recognizing potential
hazards. The project is expected to take
approximately nine months and will be completed at a cost not-to-exceed $6,000.
RECOMMENDATION: Authorize
the Acting General Manager to execute a contract with the Watershed Institute
of California State University at Monterey Bay to study large wood in the main
stem of the Carmel River for a cost not to exceed $ 6,000. The Administrative Committee considered this
item at its August 12, 2003 meeting and recommended approval by a vote of 2 to 0.
IMPACT
ON STAFF AND RESOURCES: Funds for this study were included in the
FY 2003-2004 budget adopted on June 16, 2003, under Program/Line Item No.:
2-3-3 Carmel River large wood inventory, Account 4/5-7855.03. The contract with CSUMB will be administered
by Larry Hampson, the District’s Water Resources Engineer.
BACKGROUND:
Large wood, which is defined here as pieces of
fallen or cut trees and branches that are six inches in diameter or greater and
longer than five feet, was routinely removed from the Carmel River or cut up by
property owners and agencies responsible for channel and bridge maintenance. The primary purpose of this activity was to
reduce the potential for log and debris dams and consequent damage to
streambanks and infrastructure during high flows. This had the effect of removing or reducing a
significant quantity of large wood from the system.
The
listing of California red-legged frogs (Rana aurora draytonii) in 1996
and steelhead (Oncorhynchus mykiss) in 1998 as threatened under the
Federal Endangered Species Act (ESA) has drawn attention to the value that
riparian vegetation and woody debris have to these species and aquatic species
in general. Large wood was historically
a large component of stream systems around the world. Large wood adds biological diversity, forms
pools, regulates sediment flow, traps spawning gravels, provides shade and
cover, and creates a more complex stream environment.
As
part of an application to the U.S. Army Corps of Engineers for authorization to
carry out routine maintenance in the Carmel River, MPWMD recently completed Final
Guidelines for Vegetation Management and Removal of Deleterious Materials for
the Carmel River Riparian Corridor (MPWMD, March 2003), which include
recommendations for managing large wood in the channel bottom; however, the
guidelines proposed for large wood were developed without the benefit of
detailed knowledge of the size, frequency, and function of large wood.
In
the summer and fall of 2002, MPWMD authorized a pilot study of woody debris in
the main stem in cooperation with the Watershed Institute of California State
University at Monterey Bay. That study set up a data collection protocol and
collected information along eight miles of the channel bottom between the
Carmel River lagoon at River Mile (RM) 0.5 and San Clemente Dam at RM
18.6. High flows in December 2002
halted data collection, so that slightly less than 50% of the main stem was
sampled. The study yielded important
information about the number of woody debris accumulations in the Carmel River,
their orientation, and their apparent influence on channel morphology. Study products included maps showing large
wood accumulations and detailed information about wood accumulations. Maps and data can be incorporated into
MPWMD’s geographic information system (GIS) for analysis and future comparison
with similar studies.
Information
from the 2002 study highlights three important points: 1.) large wood is scarce
along the river bottom; 2.) a relatively small percentage of large wood (less
than 10%) contributes to streambank destabilization; and 3.) about 25% of large
wood has a beneficial effect on aquatic habitat by creating scour holes and
cover. Staff proposes to follow up on
the previous study by completing a survey of the entire river bottom between
the Carmel River lagoon at RM 0.5 and the San Clemente Dam at RM 18.6. A report
and maps detailing the location, size, and function of large wood in the main
stem of the river would be developed.
Completing an inventory of large wood in
the
river system should give MPWMD a comprehensive database that will provide
information necessary to assess the importance of large wood in the Carmel
River and to develop appropriate management strategies.
The Watershed Institute of California State University at Monterey Bay, which contracts with several local agencies to provide watershed research and analysis, will provide a student and a faculty advisor who are both experienced with such an inventory to carry out a study of large wood along the Carmel River, as detailed in Exhibit 2-A, “2003 Carmel River Large Woody Debris Assessment.” As shown in Exhibit 2-B, a map of the Carmel River Watershed, the assessment would occur in the main stem of the river starting near the lagoon at RM 0.5 and extending upstream to the San Clemente Dam at RM 18.6. Because work will be carried out below the level of “ordinary high water,” where the public has rights of access, permission to gather data in this area on private property in the Carmel River is not required. However, MPWMD may need to assist in finding public access to the river bottom and in contacting private landowners for additional access to the river. As a part of the contract entered into with CSUMB, MPWMD will require proof of general liability insurance and workers compensation insurance that is commensurate with the project scope. Field work is anticipated to be completed in fall 2003 prior to winter rains and high flows. Data analysis and report preparation will be completed in the winter/spring of 2004.
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