Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Arid West Region (Version 2.0)

U.S. Army Corps of Engineers (USACE) | September 9th, 2008

This document is one of a series of Regional Supplements to the Corps of Engineers Wetland Delineation Manual, which provides technical guidance and procedures for identi

This document is one of a series of Regional Supplements to the Corps of Engineers Wetland Delineation Manual, which provides technical guidance and procedures for identifying and delineating wetlands that may be subject to regulatory jurisdiction under Section 404 of the Clean Water Act or Section 10 of the Rivers and Harbors Act. The development of Regional Supplements is part of a nationwide effort to address regional wetland characteristics and improve the accuracy and efficiency of wetland-delineation procedures. This supplement is applicable to the Arid West Region, which consists of all or portions of 12 states: Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Texas, Utah, Washington, and Wyoming.

Regulatory steps needed to protect and conserve wetlands not subject to the Clean Water Act

California State Water Resources Control Board (SWRCB) | November 17th, 2003

This report responds to legislative direction to describe the steps and resources needed to protect California wetlands and other waters that are not covered by the feder

This report responds to legislative direction to describe the steps and resources needed to protect California wetlands and other waters that are not covered by the federal Clean Water Act (CWA). It gives special attention to "isolated" waters removed from CWA jurisdiction by the U.S. Supreme Court's 2001 decision in Solid Waste Agency of Northern Cook County v. U.S. Army Corps of Engineers (SWANCC). Wetlands and riparian areas support extraordinary biodiversity and are uniquely important in sustaining the hydrologic, chemical, and ecological integrity of broader aquatic systems. However, for physical and legal reasons, they present special management challenges. Neither CWA nor the state Porter-Cologne Water Quality Control Act (Porter-Cologne) were designed to conserve wetlands, and their regulatory protection is therefore often problematic and incomplete.

Relationship between wetland condition, stress, and buffer

San Francisco Estuary Institute (SFEI) | April 25th, 2016

Relationship between wetland size and CRAM condition scores for depressional wetlands

San Francisco Estuary Institute (SFEI) | March 28th, 2016

Resilient landscape vision for Lower Walnut Creek

San Francisco Estuary Institute (SFEI) | November 30th, 2016

Lower Walnut Creek (Contra Costa County, CA) and its surrounding landscape have undergone considerable land reclamation and development since the mid-nineteenth century.

Lower Walnut Creek (Contra Costa County, CA) and its surrounding landscape have undergone considerable land reclamation and development since the mid-nineteenth century. In 1965, the lower 22 miles of Walnut Creek and the lower reaches of major tributaries were converted to flood control channels to protect the surrounding developed land. In the recent past, sediment was periodically removed from the lower Walnut Creek Flood Control Channel to provide flow capacity and necessary flood protection. Due to the wildlife impacts and costs associated with this practice, the Contra Costa County Flood Control and Water Conservation District (District) is now seeking a new channel management approach that works with natural processes and benefits people and wildlife in a cost-effective manner. Flood Control 2.0 project scientists and a Regional Science Advisory Team (RSAT) worked with the District to develop a long-term management Vision for lower Walnut Creek that could result in a multi-benefit landscape that restores lost habitat and is resilient under a changing climate. Development of the Vision began with technical analyses focused on understanding past and present landscape functioning and the changes to key processes and landscape features over the past 150 to 200 years. The key findings from these analyses include the following: • Landscape change – During the mid-19th century, lower Walnut Creek was surrounded by a continuous expanse of tidal wetlands occupying approximately 5,000 acres. Perennial freshwater marsh, willow thicket, and alkali meadow formed a large non-tidal wetland complex that adjoined the tidal marsh on its southern end. Over the past century and a half, the non-tidal wetland complex has been lost completely and the tidal wetland area has decreased by 40%. The remaining marsh areas are highly fragmented and cut-off from Walnut Creek by engineered levees. The loss of tidal wetland area has resulted in a substantial decrease in tidal prism and contributed to current in-channel sediment accumulation issues. Around the mouth of Walnut Creek, sediment accumulation has caused the position of the shoreline to expand into the Bay by up to half a mile. • Sediment accumulation – Since 1965, approximately 1.4M cubic yards of sediment have been removed from lower Walnut Creek, with approximately 70% coming from the tidal zone downstream of head of tide (i.e., the inland extent of tidal inundation at mean higher high water). Repeat channel cross-section surveys indicate that the channel quickly fills in with sediment following dredging events (due in large part to decreased tidal prism and associated channel scour capacity) and that the channel bed elevation is currently at or near “quasi-equilibrium.” A channel sediment budget for 1965-2007 indicates that approximately 80% of the watershed-derived sediment made it through lower Walnut Creek and out to the Bay, while the remaining 20% was likely deposited directly following channel construction and subsequent dredging events.

Restoration Vision for the Laguna de Santa Rosa

San Francisco Estuary Institute (SFEI) | April 1st, 2020

The Laguna de Santa Rosa, located in the Russian River watershed in Sonoma County, CA, is an expansive freshwater wetland complex that hosts a rich diversity of plant a

The Laguna de Santa Rosa, located in the Russian River watershed in Sonoma County, CA, is an expansive freshwater wetland complex that hosts a rich diversity of plant and wildlife species, many of which are federally or state listed as threatened, endangered, or species of special concern. The Laguna is also home to a thriving agricultural community that depends on the land for its livelihood. Since the mid-19th century, development within the Laguna and its surrounding watershed have had a considerable impact on the landscape, affecting both wildlife and people. Compared to predevelopment conditions, the Laguna currently experiences increased stormwater runoff and flooding, increased delivery and accumulation of fine sediment and nutrients, spread of problematic invasive species, and decreased habitat for native fish and wildlife species. Predicted changes in future precipitation patterns and summertime air temperatures, combined with expanding development pressure, could exacerbate these problems. People who manage land and regulate land management decisions in and around the Laguna, including landowners; federal, state, and local agencies; and local stakeholders, are seeking a long-term management approach for the Laguna that improves conditions for the wildlife and people that call the Laguna home. The California Department of Fish and Wildlife and Sonoma Water funded the Laguna-Mark West Creek Watershed Master Restoration Planning Project to develop such a management approach, focusing on the need to identify restoration and management actions that enhance desired ecological functions of the Laguna, while also supporting the area’s agriculture and its local residents.

Restoring the Heart of a Healthy Estuary: A Review of Restoration in the Sacramento–San Joaquin Delta and Suisun Marsh

Publisher not available | December 19th, 2025

The restoration of native species-dominated ecosystems is critical for improving ecosystem health and meeting policy goals in the Sacramento–San Joaquin Delta and Suisu

The restoration of native species-dominated ecosystems is critical for improving ecosystem health and meeting policy goals in the Sacramento–San Joaquin Delta and Suisun Marsh (upper San Francisco Estuary, collectively), one of the largest estuarine systems in North America. To accomplish large-scale restoration in this heavily altered system, a variety of projects, programs, and motivations inform restoration planning and implementation. Chapter 4 of the Delta Plan synthesizes restoration goals across these efforts to produce comprehensive ecosystem restoration targets of between 60,000 and 80,000 acres across seven ecosystem types by 2050, but a comprehensive review of restoration progress and planning to date is needed. To fill this gap, this paper analyzes the current state of ecosystem restoration in the upper San Francisco Estuary in the context of the Delta Plan targets. We review current scientific and management literature and implementation approaches, and synthesize acreage totals across completed, in-progress, and planned projects for four ecosystem types where substantial development of restoration in the system has occurred: tidal wetland, non-tidal wetland, riparian, and floodplain. We find that tidal wetland restoration has progressed more rapidly than other ecosystem types, motivated by mitigation requirements related to the federal Endangered Species Act. Across all ecosystem types, we identify both promising progress and clear needs for accelerated planning and implementation of restoration projects to meet Delta Plan 2050 targets, and discuss ongoing needs related to science, funding, and implementation.

Reversal in estuarine sand supply driven by Holocene sea level rise: A model for sand transport in large structural estuaries, San Francisco Bay, California, USA

Elsevier | July 26th, 2024

Coastal sand supply is a critical component of shoreline stability in the face of modern threats to coastal zones such as sea level rise or anthropogenic sediment extract

Coastal sand supply is a critical component of shoreline stability in the face of modern threats to coastal zones such as sea level rise or anthropogenic sediment extraction. Understanding the natural and anthropogenically perturbed dynamics of coastal systems has become a pressing challenge for coastal communities, such as the San Francisco Bay area in the United Sates, a large structurally controlled estuary system where stakeholders seek to balance the extraction of coastal sand resources for economic use and ensure sufficient sand supply for sustaining natural coastal environments. Developing accurate and comprehensive models of sand inputs and transport pathways in different types of coastal systems is imperative to balancing these competing needs. While estuarine sediment transport has been well-studied in many systems globally, structurally controlled estuaries in tectonically active settings have received relatively less attention. The prevailing hypothesis for sediment transport through San Francisco Bay describes active input and transport of sand from a large integrated regional catchment, through multiple subembayments, and out to Pacific coast beaches; a model contrary to prevailing understanding of highstand estuarine sediment transport in most settings. We test this model by applying comprehensive sand provenance analysis to surface and near-surface sand deposits in and around San Francisco Bay coupled with sand residence time data from optically stimulated luminescence (OSL) dating. New provenance results include sand petrography modal abundances, bulk geochemistry, and U-Pb detrital zircon geochronology from 27 Holocene samples throughout the San Francisco Bay region. Collectively, these new results highlight marked sediment provenance and residence time differences between San Francisco Bay structural subembayments. In particular, distinct compositional differences and OSL ages exist between sand in the bayhead region of the estuary (OSL ages ca. 4 ka; Sacramento River/local provenance) and sand from the more distal bay regions and the Pacific coast (OSL ages ca. 1 ka; integrated Sierra Nevada provenance). These provenance differences better support a revised sand input and transport model with disconnected depocenters across three structurally restricted subembayments from bayhead to the Pacific coast. New data suggest that at present the bayhead region receives limited supply from the Sacramento-San Joaquin Delta drainage with subsidiary supply from local circum-bay drainages. Sand deposited in the region from the Pacific coast through the inlet (Golden Gate) and into the estuary consists of a combination of tidal winnowing and reworking of “relic” sand from lowstand periods combined with sand eroded from Pacific coast sea cliffs, and sand supply from local Coast Range drainages. These results suggest that sand is likely not transported directly to the Pacific coast from the Sacramento-San Joaquin Delta under modern conditions. Moreover, it is likely that structural constrictions between the main estuary and outer coast and between estuary subembayments cause abrupt cessation of sediment input from the main regional drainage during marine flooding, a feature likely common to large structurally controlled estuaries globally. This revised model for San Francisco Bay sand transport illustrates the need for research targeted at interpreting natural sand transport pathways in coastal systems where coarse sediment supply is a sustainability concern.

RipZET: Documentation of Tool Demonstration in Marin County

San Francisco Estuary Institute (SFEI) | March 31st, 2015

The San Francisco Estuary Institute and Aquatic Science Center (SFEI‐ASC) has developed the Riparian Zone Estimation Tool (RipZET) to help the California community of

The San Francisco Estuary Institute and Aquatic Science Center (SFEI‐ASC) has developed the Riparian Zone Estimation Tool (RipZET) to help the California community of riparian interests visualize and characterize riparian areas as habitat unto themselves as well as their capacity to function as buffers for protecting the ecosystem services of the state’s streams, lakes and wetlands. RipZET is a tool used with Geographic Information System (GIS) and spreadsheet software to estimate “functional riparian width,” or the width associated with different riparian functions (e.g., large woody debris input, shading, floodwater storage), which varies with channel type and watershed location. The concept of functional riparian width is central to the riparian definition recommended by the National Research Council (NRC 2002) and is integral in many recently developed riparian design and management guidelines around the country.

Salton Sea Management Program Phase 1: 10-Year Plan Imperial and Riverside Counties, California Draft Environmental Assessment

U.S. Army Corps of Engineers (USACE) | June 21st, 2022

This Environmental Assessment (EA) was prepared pursuant to the National Environmental Policy Act (NEPA) and analyzes and discloses the effects of the implementation of t

This Environmental Assessment (EA) was prepared pursuant to the National Environmental Policy Act (NEPA) and analyzes and discloses the effects of the implementation of the Salton Sea Management Program’s (SSMP’s) Phase 1: 10-Year Plan (SSMP 10-Year Plan or Applicant’s Proposed Project) being proposed by CNRA (California Natural Resource Agency), California Department of Water Resources (DWR), and the California Department of Fish and Wildlife (CDFW), collectively known as the SSMP team. The SSMP team is seeking Department of the Army (DA) authorization from the United States Army Corps of Engineers (Corps), Los Angeles District, pursuant to Section 404 of the Clean Water Act (CWA; 33 USC §1344). The SSMP 10-Year Plan proposes to implement a total of 29,800 acres of aquatic habitat restoration and dust suppression projects around the perimeter of the Salton Sea. At least 50 percent of the project acreage will be created as habitat for fish and wildlife that depend on the Salton Sea ecosystem and the remainder will be projects to suppress dust.