Humanity relies on well-functioning freshwater ecosystems, but this dependence has led to their overuse and destruction. Major drivers and threats to freshwater ecosystems are entirely due to human activity, including urbanization, land-use change, water extraction, river alteration by dams and infrastructure, exploitation of fisheries, water pollution, climate change and invasive species. As a consequence, global freshwater species populations have declined by 83% since 1970. During the last century, it is estimated that the world has lost 50% of its wetlands, 40% of its forests and 35% of its mangroves.
Strong integrated planning in water-related sectors – such as agriculture, energy, urban, and industry – can slow, stop or even reverse this trend. However, the complexity of water infrastructure, and its interplay with freshwater ecosystems and connections to urbanization, often contribute to a fragmented governance system and a lack of policy coherence and coordination. The result is weak water planning, with poor ecosystem outcomes.
One way to improve these outcomes is to more thoroughly consider ecosystem needs throughout the planning process. Through the Water Beyond Boundaries initiative, we are working to pinpoint the crucial connections required to do this as part of the effort to implement integrated water resources management at all levels (Sustainable Development Goal 6.5.1).
Our aim: provide actionable guidance on how governments can include ecosystems front and center in water planning, through technical analysis, policy engagement and cooperation among sectors and stakeholders.
We focused on three watersheds to determine how ecosystems are currently considered in water planning, and to identify any gaps. We researched the governance structure and policies in each watershed, investigating current legal frameworks and interviewing institution representatives. Key insights from this review for the Sacramento-San Joaquin Delta in California, Magdalena Basin in Colombia and Mekong Basin in Southeast Asia are summarized below.
Sacramento-San Joaquin Delta, California
Population: Over 40 million
Area: 109 000 km2
Main institutions: Department of Water Resources, State Water Resources Control Board
Main regulations: Endangered Species Acts formulated by state and federal agencies play a significant role in managing freshwater ecosystems. In setting water management goals, officials consider broader societal aims, including public and ecosystem health and fairness. Ecosystem-based management is reported as part of the integrated water resources management process, which focuses on coordination and funding of local water management projects while managing their impacts on ecosystems.
Magdalena Basin, Colombia
Population: Over 35 million
Area: 273 000 km2
Main institutions: National Ministry of the Environment and local environmental authorities
Main regulations: The National Policy of Integrated Management of Biodiversity and Ecosystem Services acknowledges that the connectivity of ecosystems depends on a spatial multiscale process that needs to be considered in water planning. Based on this, ecosystem services are included in the land use and planning process. Still, the importance of water bodies’ ecosystem health and of maintaining habitat functions is less central to freshwater ecosystems protection.
Mekong Basin, South East Asia
Population: Over 70 million
Area: 795 000 km2
Main institutions: The Mekong River Commission (MRC) was established by the governments of Cambodia, Laos, Thailand and Viet Nam.
Main regulations: The Mekong Basin Development Strategy (BDS) 2021–2030 guides all relevant actors involved in Mekong water-related issues towards achieving improvements in the environmental, social and economic state of the Mekong River Basin. One of the five strategic priorities of the BDS is to maintain the ecological function of the Mekong River. This requires a national and regional focus on limiting the modification of the flow regime and stopping the decline in wetlands, in order to achieve an acceptable balance between ecological function, economic development and climate resilience.
Based on these case studies, we have identified a gap in ecosystems consideration at the beginning of the water planning process. To ensure water systems have functional flows – or flows that sustain the conditions necessary for species’ survival – an ecosystem’s needs should be part of the watershed plan, rather than only considered at the end of the process.
Water planners can use a variety of tools and approaches to gain data and information on the water needs of freshwater ecosystems. They are:
Environmental flows (eFlows) refer to the required quantity and quality of water for freshwater ecosystems. By conducting eFlow assessments in the early stages of water planning, officials can better consider how planned infrastructure (such as dams and hydropower) will affect ecosystems and can consider various flow management options.
Habitat simulation techniques can be paired with eFlow assessments to create more targeted flow objectives. These techniques – which include establishing criteria for the target life stages of wildlife – require data, either from experts or observation, that is often not available. However, if achievable, such habitat-based assessments can also help planners define specific aspects of the interplay between flows and topography, leading to the more accurate identification of “functional flows”, which are flows that sustain the conditions necessary for species’ survival.
Valuing ecosystem services
An alternative approach to flow- and habitat-based solutions is to focus on valuing ecosystem services. This involves quantifying the value of goods and services that humans derive from the ecosystem. For example, this could include the various uses for which water is diverted, the freshwater fish and products made possible by in-situ water or the spiritual or aesthetic benefits of an area of water. Various methods exist, but the resulting monetized values are highly debatable and have rarely helped in the protection of ecosystems.
River restoration is a last-resort solution, used when degradation is so extreme that intentional work is needed to improve hydrologic, geomorphic and ecological processes. Such restoration is becoming more widespread, thanks to the lack of ecosystem consideration – and protective measures – in water management. Restoration is sometimes the necessary and only option for highly developed areas where degradation is extreme, but it is expensive and its effectiveness is limited.
Water managers can use available technical analyses, such as those above, to define what amounts of water are needed to maintain freshwater ecosystems. Many of these approaches historically require large amounts of data, but officials can narrow their focus – and thus limit data needs – by concentrating on key elements of the natural flow regime including water quantity, water quality, sediment and nutrient that are known to sustain ecosystems.
One way to do this is by focusing on the flows needed to maintain habitat needed for specific species and life stages. For instance, fish passage requires specific flows at certain times of the year. Managers can quantify those flows and manage the system to provide them when and where they are needed. This approach combines technical information from flow with habitat-based ecosystems consideration to come up with solutions that maintain and restore habitat in key hotspots of the river system. This approach has gained popularity in California and is called functional flows.
Functional flows are simply flow values that serve ecological purposes. To define functional flows the initial step is to identify ecologic functions, such as passage or spawning, and the amounts of water they need at particular times of the year. The functional flows approach integrates measures of flow and channel shape that maintain physical habitat health. This method presents a promising alternative to define a functional flow path to reach a balance sustainable water use.
Using existing technical advances within a functional flows framework will help identify specific targeted amounts of water that will maintain ecosystems while also providing water for societies and sustainable development. Governments and institutions can pair this with strengthened stakeholder engagement and policy coherence to carve paths towards ecosystems inclusion.
- Strengthen policy coherence and dialogue: This can be achieved by empowering water managers to interact with other sectors such as agriculture, urban, energy and industry to make sure that water plans incorporate other sector perspectives and vice versa. The main goal here is to highlight the options available to keep water for the ecosystems while supporting other services.
- Promote the combination of top-down and bottom-up approaches: Communities that depend on freshwater ecosystems need to be engaged in the identification of future alternatives. Their local knowledge can contribute to a more comprehensive view of adaptation options and development pathways that maintain ecosystems health.
- Merge decision tools of hydrology, ecology, and societal needs into robust decision support systems: Established practices such as eFlows, habitat mapping and the valuation of ecosystem services can be used through a functional flows framework to allow for a more precise prescription of the water that is needed for ecosystems. Such technical advances can be merged with participatory engagement to bring ecosystem voices to the table.