Click here to read the White Paper (Jian Wang, David E. Rosenberg, Kevin G. Wheeler, and John C. Schmidt). Here’s the executive summary:
Colorado River managers and stakeholders face many uncertainties—issues like climate change, future water demand, and evolving ecological priorities. Managers and stakeholders are looking for new ways to communicate about uncertain future conditions, help cope with an uncertain future, and develop public policy when future conditions are highly uncertain. Historically, Colorado River managers have operated Lake Powell and Lake Mead under the assumption that the future natural flow regime of the Colorado River at Lee Ferry will resemble the previously observed regime, but most climate scientists believe that the flow regime is changing, and that future flows will be lower, more variable, and more uncertain.
• It is also difficult to predict future demand for Colorado River water, future river ecosystem conditions, or the values that future generations will attach to those ecosystem conditions. These uncertainties present immense challenges when developing river management policies to enhance water supplies and ecosystem condition.
• To help Colorado River stakeholders think about, talk about, and better manage the river in the face of these unknowns, this white paper distinguishes four levels of uncertainty. Future conditions can be described by point estimates with small ranges (Level 1), probabilities (Level 2), scenarios of possible future conditions (Level 3), or a level of complete unknown (Level 4).
• We represent each level with day-to-day and Colorado River examples. These examples illustrate how the further a stakeholder attempts to peer into the future, the greater the level of uncertainty.
• Managers and stakeholders can classify the uncertainty level of each key system factor to guide decisions about which modeling tools and public policies to use. Tools include defining alternative scenarios, Many Objective Robust Decision Making (MORDM), Decision Scaling (DS), and Dynamic Adaptive Policy Pathways (DAPP) for uncertain future conditions that can only be described by scenarios (Level 3).
• There is need to expand the discussion about how to renegotiate the Interim Guidelines and the Lower Basin Drought Contingency Plan (DCP). This discussion should consider uncertainties in future hydrology, demands, and river ecosystem conditions that can only be described by scenarios (Level 3). Revisions to the Interim Guidelines should (1) include more information about future conditions as new information becomes available, (2) define interim decision points (called signposts) when existing policies should be reconsidered, and (3) allow more flexibility in day-to-day management decisions that respond to unforeseen conditions.
• This white paper suggests that new guidelines designed to adapt to uncertain future hydrology, water demand, and river ecosystem conditions are likely to look quite different than the current guidelines, which seek to provide certainty about the amount of water managers can divert.
• New guidelines that acknowledge different levels of uncertainty levels will be more adaptable, more flexible, and will be better able to anticipate and respond to a wider range of future Colorado River conditions. This adaptability and flexibility can help avert future crises.