5.1A – Stream Channel Modification – Channelization/Channel Modification

Management Measure

  1. Evaluate the potential effects of proposed channelization and channel modification on the physical and chemical characteristics of surface waters, and on aquatic and riparian habitat.
  2. Plan and design channelization and channel modification projects to reduce undesirable impacts to water quality and to the aquatic and riparian habitat.
  3. Operate and maintain channels and channel modification projects to improve water quality, and promote aquatic and riparian ecosystem functions.
  4. Reduce or limit the amount of service roads adjacent to stream channels.

Channelization and channel modification activities include projects that straighten, widen, deepen, and/or dredge stream channels of debris and sediment. Categories of channelization and channel modification projects include flood control and drainage, navigation, sediment control, infrastructure protection, mining, channel and bank instability, habitat improvement or enhancement, recreation, and flow control for water supply (Watson et al., 1999). Channelization and channel modification activities diminish the quality and diversity of aquatic and streamside habitats by altering water temperature and flow, as well as modifying or arresting stream channel-forming processes (sediment erosion, transport, and deposition).

Dredging and reduced sediment loads from channelization activities has disconnected floodplains from their source of sediment - effectively narrowing riparian habitats by increasing depth to groundwater, thus severely degrading the functionality of these riparian ecosystems. Some water quality impairments result from the loss of riparian ecosystem function, these include increased sediment, nutrients and temperature which can cause algae blooms and in extreme cases, eutrophication. Typical water quality constituents that are measured to demonstrate the changes to physical and chemical parameters of the affected surface waters include: dissolved oxygen, salinity, sediment (or turbidity), nutrients, and chemicals related to surrounding land-use activities.

Management Practice

  1. Use models and common methodologies to evaluate the effects of proposed channelization and channel modification projects on the existing physical and chemical characteristics of surface waters and on aquatic and riparian habitat. Refer to MM 5.2B, Flow and Temperature Maintenance for more information on models that consider how channelization/channel modification activities effect surface water temperature and flow.
  2. Management practices that address planning for levee construction activities are discussed under MM 5.1B, Dam and Levee Construction.
  3. Address fish passage concerns prior to installing any grade control structure.

Planning and Evaluation of Channelization/Channel Modification Projects

  • Evaluate the potential impact of the project using rapid bioassessment protocols, such as CRAM and rapid aquatic bioassessment. See MM 6, Wetlands, Riparian Areas, and Vegetated Treatment Systems for more information on management practices and information sources related to evaluating sites.
  • Use watersheds (CALWATER) as the scale for modeling and planning. Work to integrate analysis into watershed plans, land-use plans, and new development plans. Several geomorphic assessment methodologies are available that relate watershed drainage into stream channels.
  • Apply the river continuum concept to determine if the project is appropriate for the watershed.

Types of Geomorphic Models (see MM 5.2B for more information on modeling stream flow)

  • Channel evolution model (CEM) developed by Hupp and Simon, identifies six geomorphic stages of channel response and was developed and extensively applied to predict empirical stream channel changes following large-scale channelization projects in western Tennessee.
  • Rosgen Classification System relies on the identification of bankfull field indicators also referred to as regional curves. Bankfull discharge is the flow of water required to leave the channel and enter the floodplain; it is conceptually similar to a channel-forming flow or calculated effective discharge. This approach assumes the alluvial stream is in equilibrium.

Expert Judgment and Environmental Goal Focused Models

  • Bureau of Land Management, Proper Functioning Condition (PFC) is a methodology for assessing the instantaneous physical functions of riparian and wetland condition.

Reduce or eliminate the amount of service roads adjacent to channels.

Operation and Maintenance of Channels

  • Grade control structures can be installed to mitigate for the loss of floodplain width or may be used for streams with naturally high sinuosity (such as headwaters or streams with a high elevation gradient). Grade control structures (or check dams) are hydraulic barriers (weirs) installed across streams to stabilize the channel and prevent upstream degradation by controlling headcuts and scour holes. These structures can be built with a variety of materials, including sheet piling, stone, gabions, or concrete. Grade control structures are often used to remove natural sinuosity of streams.

    Keep in mind that removing the natural meander of a stream within its bed usually leads to stream bank erosion in predictable meander-type patterns and often requires management practices to protect or rehabilitate eroded streambanks. See MM 5.2A, Managing Hydromodification Impacts, Streambank and Shoreline Protection for management practices related to streambank erosion control.
  • Maintain streamside vegetative cover to protect or rehabilitate eroded streambanks. Streambank protection using vegetation is probably the most commonly used practice, particularly in small tributaries. Vegetative cover, also used in combination with other structural practices, is relatively easy to establish and maintain, is visually attractive, provides shade, and is the only streambank stabilization method that can repair itself when damaged. Appropriate native plant species should be used.
  • Limit the frequency and duration of clearing and/or dredging of sediment and materials from channels. Make sure appropriate permits are obtained prior to initiating any activity within a stream channel.


  • California Department of Fish and Wildlife (DFG) has jurisdictional authority over wetland resources associated with rivers, streams, and lakes under California Fish and Game Code sections 1600 to 1607 (City of Palo Alto, 2001). The DFG has the authority to regulate work that will substantially divert, obstruct, or change the natural flow of a river, stream, or lake; substantially change the bed, channel, or bank of a river, stream, or lake; or use material from a streambed. Typical activities regulated by DFG under sections 1600-1607 authority include rechanneling and diverting streams, stabilizing banks, implementing flood control projects, river and stream crossings, diverting water, damming streams, gravel mining, and logging operations. The DFG requires completion of a Streambed Alteration Agreement, which is a mutual agreement between the DFG and the project proponent. After the Department receives a complete notification package, it will determine whether you will need a Lake or Streambed Alteration Agreement for your activity. An agreement will be required if the activity could substantially adversely affect an existing fish and wildlife resource. If an agreement is required, the Department will conduct an onsite inspection, if necessary, and submit a draft agreement to you. The draft agreement will include measures to protect fish and wildlife resources while conducting the project. If you are applying for a regular agreement, the Department will submit a draft agreement to you within 60 calendar days after your notification is complete. The 60-daytime period will not begin until your notification is complete. The 60-day time period does not apply to notifications for long-term agreements.
  • California Environmental Resources Evaluation System (CERES) is an information system developed by the California Resources Agency to facilitate access to a variety of electronic data describing California’s rich and diverse environments. The goal of CERES is to improve environmental analysis and planning by integrating natural and cultural resource information from multiple contributors and by making it available and useful to a wide variety of users.
  • CALFED Bay-Delta Program aims to improve the quality and reliability of California’s water supplies and revive the San Francisco Bay-Delta ecosystem. Its Web site contains information about water supply, water quality, and ecosystem restoration.
  • Clean Water Act Section 401 Certification Program administered by Regional Water Quality Control Boards (RWQCBs), review projects that require a federal permit under CWA section 404 or that involve dredge or fill activities that may result in a discharge to waters of the United States. This is to ensure that the State’s interests are protected on any federally permitted activity occurring in or adjacent to waters of the State. Detailed information about CWA section 401 in California, including a description of the program, resources, legal background information, proposed projects, and links, are described on the SWRCB Web site.
  • US Army Corps of Engineers 404 Permitting Program, Sacramento District / Regulatory Program administers and enforces Section 10 of the Rivers and Harbors Act of 1899 and Section 404 of the Clean Water Act. Under Section 10, a Corps permit is required for work on structures in, over or under navigable waters of the United States. Under Section 404, a Corps permit is required for the discharge of dredged or fill material into waters of the United States. Many waterbodies and wetlands in the nation are waters of the United States and are subject to the Corps' Section 404 regulatory authority.
  • US Fish and Wildlife Service, National Fish Passage Program uses a voluntary, non-regulatory approach to remove and bypass barriers. The Program addresses the problem of fish barriers on a national level, working with local communities and partner agencies to restore natural flows and fish migration. The Program is administered by National and Regional Coordinators, and delivered by Fish and Wildlife Management Assistance Offices, with their 300 biologists located across the Nation.

Information Resources

  • North Delta Improvements Project is under the Department of Water Resources, presents unique opportunities for synergy in achieving flood control and ecosystem restoration goals.
  • South Delta Improvement Project (SDIP) is to incrementally maximize diversion capability into Clifton Court Forebay, while providing an adequate water supply for diverters within the South Delta Water Agency, and reducing the effects of State Water Project exports on both aquatic resources and direct losses of fish in the South Delta
  • Bay Institute, Bay Restoration Program describes several bay and wetland restoration projects that are part of an effort to improve the Bay-Delta Ecosystem. The site provides links to information about the Bay, news and publications, and the STRAW (Students and Teachers Restoring A Watershed) Project, which is an organization that plans and implements watershed studies and restoration projects in Marin, Sonoma, and Napa counties.
  • Salmon Restoration Project is the result of cooperation between the California Conservation Corps and California Department of Fish and Game. The agencies have been working in partnership with private and public landowners to restore California’s salmon and steelhead habitat by adding instream structures. These structures provide shelter for fish, help reduce water temperatures, and add ecological complexity to the stream channel.
  • Ohio Department of Natural Resources – Stream Management Guide Fact Sheets This is a compilation of fact sheets on technical guidance for streambank and instream practices, general stream management, and stream processes.
  • USDA Natural Resources Conservation Service, Stream Visual Assessment Protocol this document outlines methods useful for field conservationists and landowners for the evaluation the ecological condition of a stream.
  • Riparian Habitat Joint Venture, started by the California Partners in Flight (CalPIF), is a collaborative effort between 18 federal, state, and private organizations. The focus of the venture is to protect and improve riparian zones bordering streams and lakes.
  • Sacramento River Riparian Habitat Program is working to ensure that riparian habitat management along the river addresses the dynamics of the riparian ecosystem and the reality of the local agricultural economy.
  • WATERSHEDS: Water, Soil and Hydro-Environmental Decision Support System contains fact sheets that provide information on a variety of techniques for management practices, including soil bioengineering, structural streambank stabilization, and instream practices.
  • USACE - ERDC/CHETN-VIII-3, December 2001, Design considerations for siting grade control structures
  • USEPA, Biocritiera Website has information on bioassessment protocols.


Cooper, J.R., and J.W. Gilliam. 1987. Phosphorus redistribution from cultivated fields into riparian areas. Soil Science Society of America Journal

Federal Interagency Stream Restoration Working Group (FISRWG). 1998. Stream Corridor Restoration: Principles, Processes, and Practices. PB98-158348LUW. Federal Interagency Stream Restoration Working Group, Washington, DC.

Lowrance, R.R., R.L. Todd, and L.E. Asmussen. 1983. Waterborne Nutrient Budgets for the Riparian Zone of an Agricultural Watershed. Agriculture, Ecosystems and Environment 10:371-384.

Phillips, J.D. 1989. Nonpoint source pollution control effectiveness of riparian forests along a coastal plain river. Journal of Hydrology 110(1989):221-237.

USACE. 1981. Low-cost shore protection, final report on the shoreline erosion control demonstration program (Section 54). U.S. Army Corps of Engineers. Washington, DC.

USEPA. 2007. National Management Measures Guidance to Control Nonpoint Source Pollution from Hydromodification. EPA 841-B-07-002. U.S. Environmental Protection Agency, Washington, DC.

Watson, C.C., D.S. Biedenharn, and S.H. Scott. 1999. Channel Rehabilitation: Process, Design, and Implementation. U.S. Army Engineer Research and Development Center, Vicksburg, Mississippi. Accessed in August 2005.

Whigham, D.F., C. Chitterling, and B. Palmer. 1988. Impacts of freshwater wetlands on water quality: A landscape perspective. Environmental Management 12(5):663-671.

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