Hydromodification assessment and management in California,

Hydromodification assessment and management in California,
Most jurisdictions in California are now required to address the effects of hydromodification through
either a municipal stormwater permit or the statewide construction general permit. Hydromodification is generally defined as changes in channel form associated with alterations in flow and sediment due to past or proposed future land-use alteration. Hydromodification management has emerged as a prominent issue because degradation of the physical structure of a channel is often indicative of and associated with broader impacts to many beneficial uses, including water supply, water quality, habitat,and public safety. Conversely, reducing hydromodification and its effects has the potential to protect and restore those same beneficial uses. Although hydromodification has the potential to affect all water body types, this document focuses on assessing and managing effects to streams because they are the most prevalent, widely studied, and arguably most responsive type of receiving water.
This document has two goals, and hence two audiences. The first goal is to describe the elements of
effective hydromodification assessment, management and monitoring. The audience for this goal is
primarily the State and Regional Water Boards, since meeting this goal will require integration of
watershed and site-scale activities that are likely beyond the responsibility or control of any individual
municipality. Success will require fundamental changes in the regulatory and management approach to hydromodification that will likely advance only iteratively and potentially require one or more NPDES permit cycles to fully implement. The second goal of this document is to provide near-term technical assistance for implementing current and pending hydromodification management requirements. This goal can be achieved by municipalities within the construct of existing programs and therefore the primary audience for this aspect of the document is local jurisdictions. Achieving this goal will facilitate greater consistency and effectiveness between hydromodification management strategies, giving them a stronger basis in current scientific understanding.
Begin Date
Originator Name
Stein, E. D., et al. Tech. Report 667. CA SWRCB Stormwater Program, Southern California Coastal Water Research Project.
Global or not applicable
Hydrology, Water Board, Watershed, Watershed Management
Resource Type
Resource Owner

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