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Existing Operations and Maintenance
Although channelization began in the 1800s, the LA River as we see it today was modified to serve as a flood management system in the 1930s after multiple serious flood events resulted in loss of life and excessive damage to the channel, surrounding infrastructure, neighborhoods, and cities.
To accomplish this, Congress granted authority to the US Army Corps of Engineers (USACE) and the LA County Flood Control District (LACFCD) to construct and maintain flood management structures consisting of dams, debris basins, levees, and channels. The resulting LA River consists of 51 miles of concrete-lined and earthen sections. Currently, the USACE maintains approximately half of the LA River, while the LACFCD maintains the other half. In addition to the channel, the typical LA River right-of-way includes flood management structures such as levees and access roads. In some sections, various recreational amenities such as bike paths, parks, and trails are found within the right-of-way, while in other areas these amenities are directly adjacent to the right-of-way.
Soft Bottom Maintenance: Invasive Species
Recreational amenities are primarily maintained by municipal and other public entities and/or other special interest groups through flood permits and right-of-way use agreements.
The current operations and maintenance (O&M) activities implemented by entities along the river were evaluated by reviewing available O&M documentation, meetings with the USACE and LACFCD personnel, and performing visual assessments of the LA River.
The LACFCD and the USACE primarily maintain channel linings, outfalls, subdrain systems, levees, vegetation, and access within the limits of the embankments. These two agencies also oversee various entities with O&M obligations, primarily for recreational amenities, within the LA River right-of-way. In general, the O&M activities are managed by both agencies during routine, as-needed, or emergency basis. O&M along concrete-lined channels primarily focuses on the structural integrity of the channel. Soft-bottom (earthen-channel) O&M primarily focuses on the structural integrity of the channel walls and on channel flood capacity through invasive vegetation (such as Arundo donax) and sediment management and removal. In total, there are approximately 36 miles of concrete-lined channels and 15 miles of earthen channels.
The primary O&M challenges noted by both agencies consist of obstructed channel access, encampments of persons experiencing homelessness, encroachment issues, and regulatory hurdles (e.g., permitting from environmental resource agencies). In addition, insufficient funding, sedimentation, and vegetation management were stated as primary challenges for the USACE, and fence maintenance was stated as another primary challenge for the LACFCD. The results of this assessment, above all, illustrate the immense scale and complexity of the O&M responsibilities of the LA River. All projects proposed by the LA River Master Plan Update should be planned with clear long-term O&M strategies to ensure the physical feasibility and future success of projects along the river.