Salt Marsh History
The Santa Ana River Mainstem flood control improvement, including the Marsh Restoration Project, was authorized by Section 906(e) of the Water Resources Development Act (WRDA) of 1986 (99th Congress, 2nd Session), Public Law 99-662. The SARM Project is a regional approach to provide flood control solutions for the Santa Ana River and tributaries within San Bernardino, Riverside and Orange Counties. The SARM project includes construction of Seven Oaks Dam, modifications to Prado Dam, and improvements to the Santa Ana River Mainstem from Seven Oaks Dam to the Pacific Ocean.
Before improvements, the Santa Ana River was uncontrolled until approximately 1903 when the lower Santa Ana River was first confined to a channel after heavy flooding (Mitchell, 2006). Little is known about the composition of the Santa Ana River Marsh area prior to the more recent oil activities, but surrounding vegetation consisted of salt marsh flora and was presumably part of the historic floodplain. This area may have supported a combination of estuary, beach dunes, or coastal prairie habitat.
Project construction in the lower Santa Ana River eliminated approximately eight acres of coastal salt marsh. USACE analyzed the project’s impacts in the Phase II General Design Memorandum/ Supplemental Environmental Impact Statement (GDM/SEIS) for the Santa Ana River Flood Control Project (USACE, 1988) and proposed the acquisition and restoration of eight acres of salt marsh as mitigation plus an additional 84 acres of salt marsh for habitat enhancement. The Santa Ana River Marsh site, then in use for oil production, was selected as the mitigation/enhancement site.
West Newport Oil owned the land now occupied by the Santa Ana River Marsh as part of a larger 500-acre parcel beginning in 1943 (when oil production began) until the land was acquired by USACE. The restoration plan for the Marsh was approved in 1989 and the 92-acre parcel was subsequently acquired by USACE from West Newport Oil. At the time of purchase, there were both active and abandoned oil wells on the site, which required extensive cleanup of oil contamination (USACE, 1988). Restoration was completed by USACE in 1992. Other large scale maintenance efforts in the form of dredging accumulated sediments have occurred in the succeeding years.
USACE Report and Construction History
The following table summarizes USACE’s Marsh project reports and construction history:
|
Phase
|
Year Completed
|
Description
|
|
SARM Phase I General Design and SEIS
|
1980
|
Phase I General Design Memorandum and Supplemental Environmental Impact Statement (EIS) for Santa Ana River Mainstem
|
|
SARM Phase II General Design and SEIS
|
1988
|
Completion of the general design of the Marsh and Supplemental Environmental impact Statement (SEIS)
|
|
Initial Construction
|
1992
|
Initial grading within the Marsh limits
|
|
Tide Gates & Side Drains
|
1993
|
Installation of tide gates and side drains
|
|
Initial Planting
|
1996
|
Initial planting of vegetation after prior construction
|
|
Maintenance Dredging
|
2013
|
Maintenance event to remove approximately 77,000 yd³ of sediment
|
|
Maintenance Dredging
|
2017
|
Maintenance event to remove approximately 10,000 yd³ of sediment
|
References:
Mitchell, P. (2006). Santa Ana River Guide: From Coast to Coast – 110 miles along Southern California’s largest river system. Wilderness Press, Berkley, CA. 224 pp.
USACE – Los Angeles District. (1980) Phase I General Design Memorandum / Supplemental Environmental Impact Statement (GDM/SEIS) on the Santa Ana River Mainstem, including Santiago Creek.
USACE – Los Angeles District. (1988) Phase II General Design Memorandum / Supplemental Environmental Impact Statement (GDM/SEIS) on the Santa Ana River Mainstem, including Santiago Creek.