TMDL Metrics: How Do We Show Progress While Encouraging the Right Actions?
Success of a TMDL program requires a balance of long and short term objectives. In the long term, performance metrics must show progress toward meeting the TMDL numeric objectives. In the short term, the same metrics should also provide feedback on the effectiveness of management actions as they are incrementally implemented. For many programs, the current TMDL metrics are often confounded by outside factors or are too slow in their signal response to provide meaningful information for adaptive management. As a solution, we have developed a methodology to identify a suite of performance metrics that provides feedback on the effectiveness of actions and can demonstrate the long-term desired system response toward the ultimate TMDL reduction goals with the implementation of those actions.
In partnership with Napa County resource managers, 2NDNATURE (2N) developed a planning matrix to identify the best set of performance metrics to meet the Napa River Sediment TMDL. Metric selection considers several key concepts: (1) cost associated with collecting, managing and analyzing the data; (2) sensitivity to management actions, independent of the climatic signal; (3) precision of the data collection and analysis methods; (4) ability to provide immediate feedback to inform management decisions; (5) data ownership and availability to resource managers; and (6) technical expertise required to obtain and report the data. This process identified 3 metric categories—system response tracking, action effectiveness tracking and action tracking—that can meet a variety of TMDL program manager needs.
System response tracking is the long-term response that must be measured to show progress toward meeting the prescribed TMDL numeric targets. However, the signal of these desired system changes (e.g., reduced sediment loads, increased lake clarity) is often heavily masked by natural variability and sampling error. Tracking system response is costly and requires long-term consistent datasets to adequately isolate and evaluate if the measured changes can be confidently attributed to effective land management changes. These limitations require supplemental metrics to account for the implementation and effectiveness of actions to achieve the desired system response.
Action effectiveness tracking metrics are performance metrics tied directly to the management actions that have been prioritized to improve the system (e.g., erosion control projects to reduce sediment delivery to streams). These supplemental assessments are cost-effective, highly sensitive to management actions, have high sampling precision, provide direct feedback for management and require minimal technical capabilities to collect and analyze. Currently there is a lack of simple, standardized, yet technically robust methodologies that that can yield this type of data. 2N has developed two Rapid Assessment Methodologies—Rural Road RAM and Stream RAM—that will provide this critical immediate feedback on the effectiveness of actions with regard to the Napa River Sediment TMDL.
Action tracking is the typical cataloging of the actions taken as part of the TMDL program—for instance, the number of plans written or acres of urban lands with applied BMPs. While this information allows a large number of stakeholders to contribute information and data and increases community engagement, the counting of implementation of actions performed alone cannot demonstrate progress towards the TMDL objectives.
By selecting a range of metrics from all three categories, a TMDL manager can develop a tracking and reporting program that has widespread appeal to a broad spectrum of stakeholders. The program will be feasible to implement and technically rigorous, provide timely feedback for adaptive management and will ultimately report the long-term progress of the receiving waters toward TMDL goals.
During this presentation, the audience will be engaged to apply the planning matrix to a Trash or Bacteria TMDL.