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Effects of Post-fire Runoff on Surface Water Quality Development of a Southern California Regional Monitoring Program with Management Questions and Implementation Recommendations

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Periodic wildfires are a natural component of southern California’s forest and scrubland and essential to maintaining overall ecological health of these systems. However, the frequency and intensity of wildfires has increased in association with human activities in and near natural forest and foothill areas. The effects of fire on hydrologic response and sediment loads in southern California have been noted for over 80 years, yet no coordinated monitoring of water quality following fires currently occurs. The lack of coordinated monitoring is particularly problematic in southern California because watersheds affected by fire often drain to waterbodies that support sensitive resources or that have been designated as impaired under Section 303(d) of the Clean Water Act, often for the same constituents found in post-fire runoff. Consequently, the contribution of metals, nutrients, and organic contaminants from post-fire runoff to receiving waters is poorly understood in terms of both the magnitude and persistence of potential effects.

The goal of this project is to help address the current information gaps by providing agreed upon regional post-fire water quality sampling procedures, including an implementation plan and a funding strategy. The plan provides a ready “off-the-shelf” response plan that can be quickly implemented after fires.

The post-fire monitoring program is organized around three priority management questions:

  1. How does post-fire runoff affect contaminant flux?
  2. What is the effect of post-fire runoff on downstream receiving waters?
  3. What are the factors that influence how long post-fire runoff effects persist?

A Conceptual Workplan was generated from the workshop participants entitled “Effects of post-fire runoff on surface water quality: Development of a southern California regional monitoring program with management questions and implementation recommendations”. The regional plan captures sampling design, site selection process, sampling approach, and recommended indicators for each of the monitoring questions.  The regional plan includes site selection criteria that allow for pre-selection and prioritization of potential sampling sites based on the sensitivity of potentially affected resources, presence of previous and available monitoring data, feasibility, accessibility, and ability to coordinate with other monitoring programs. Pre-selection of sites and up-front coordination will allow for more rapid and effective response following fires. Finally, the plan includes preliminary recommendations for quality assurance procedures, data management, and communication that will facilitate information sharing and ongoing coordination.

The program implementation, development and coordination will be accomplished through a post-fire runoff working group that consists of the U.S. Forest Service, U.S. Geological Survey, CAL FIRE, the regional water quality control boards, major municipalities, key landowners, and local researchers.