Thursday, April 16, 2020

Ecosystem flows

Natural flows in rivers throughout the American West have been significantly disrupted by dams and diversions, groundwater extraction, land use changes, and other human influences.  Over time this has led to the decline of freshwater ecosystems to the point that many species have become endangered.  For instance, rivers rely on natural floods for maintenance of the river channel and floodplain, and flow of critical nutrients and biota.  Large dams mute or eliminate downstream flooding (winter flood pulses) by capturing these flows in a reservoir.  Similarly most western rivers are drying up during the dry months (summer/early fall base flows), an increasing concern with more frequent drought and heat due to climate change, and the primary concern on the Ventura River.

Functional Flows, figure from "A Path Forward for California's Fresh Water Ecosystems", PPIC 2019

The diagram shown here illustrates alterations to the natural flow regime throughout the year and a proposed "Functional flow regime."  The aim of functional flows is to re-establish some of the basic river functions in highly modified systems to restore ecosystem function.

The question is how to develop a management paradigm to allocate water to functional flows and ecosystem health?

A recent report by the Public Policy Institute of California presents the case for Ecosystem Based Management as a solution to California's water problems.  Maven's Notebook presents an excellent summary of recent discussions along with the technical references.

In particular, this report concludes that the current management focus on endangered species is failing, and we need a more holistic approach:

Ecosystem-based management emphasizes the simultaneous management of water, land, and species to improve ecosystem condition for native biodiversity and human uses. It shifts the management emphasis to the social, economic, and environmental benefits that come from healthy ecosystems, rather than narrowly focusing on mitigating harm to protected species.

Sustainable watershed management plans, backed by binding comprehensive agreements, are the best way to accomplish ecosystem-based management. These agreements can be adopted by state and federal regulators to meet Clean Water Act and ESA requirements and can align other agency priorities and actions.

With ecosystem-based management, there are a suite of actions available.  The first is to establish an ecosystem water budget that is an allocation of water for the environment that functions much like a senior water right that can store, trade, and flexibly allocate that water to respond to changing conditions.

An outline of this management approach is presented in the PPIC Policy Recommendations:

Promote inclusive planning and governance

  • Identify the desired ecosystem condition
  • Establish metrics
  • Provide strong scientific support
  • Set up transparent governance
  • Ensure reliable funding

Employ multiple ecosystem management tools
  • Establish ecosystem water budgets
  • Employ functional flows
  • Manage native and non-native species
  • Manage at the appropriate scale

Encourage sustainable watershed management plans
  • Align agency actions
  • Promote comprehensive agreements
  • Set timelines and backstops
  • Update water quality control plans
  • Incentivize or mandate plans

It is important to highlight the differences between ecosystem-based management and other, often similar approaches. For example, 

      * ecosystem management seeks to manage the ecosystem for species conservation goals and objectives, such as resilient populations of native plants and animals. This is accomplished principally by constraining land and water use and often uses recovery of protected species as a primary objective. In contrast, 

      * ecosystem-based management integrates human uses into the setting of conservation goals and objectives, balancing the uses of the resource. Ecosystem-based management also differs from 

      * Integrated Water Resources Management (IWRM), which focuses principally on coordination and funding of local water management projects while managing their impacts on ecosystems.

Renewed discussion of Ecosystem-based Management supports the vision presented in the Ventura River Ecosystem blog.  This approach applies readily to the Ventura River Watershed, especially with ongoing planning for this priority basin under SGMA.  The Sustainable Groundwater Management Act provides for self-organized groundwater sustainability agencies (GSAs) and required groundwater sustainability plans.  However, in our case the Ventura River would ideally combine the two existing GSA's into a single watershed-based agency to better realize the Ecosystem-based management approach.

On this blog:

Ventura River; Ecosystem-based Management


text in italics above quoted from: 

Mavens Notebook: Ecosystem-based Management: A New Paradigm for Managing California's Freshwater Ecosystems

A Path Forward for California’s Freshwater Ecosystems, PPIC Water Policy Center, December 2019

More information: