What benefits do healthy rivers and streams provide?
River health is important to everyone who lives in a watershed . A healthy river is a resilient river that is dynamically stable and able to recover quickly after disturbance, without costly human intervention. A healthy river and its tributaries provide vital ecological functions and far-reaching benefits to the communities within a watershed. These community benefits are called ecosystem services, and we get to enjoy them for free as long as our rivers are healthy. Ecosystem services are all around you. They include things like clean and plentiful water for drinking, resilience to wildfire, thriving fisheries, abundant wildlife, water for crops and food, and simply a place of rest and respite. Healthy rivers bring intangible benefits enjoyed by both passive viewers and property owners whose land value is enhanced by the utility and sheer beauty of thriving ecosystems. They provide recreational assets cherished by residents and visitors alike. Healthy river systems also support critical biodiversity–about 80% of Colorado’s wildlife species depend on rivers and riparian habitats—and provide an irreplaceable economic resource to many counties, towns, businesses and Coloradans.
Colorado’s rivers face challenges from land use change, wildfire, pollution, climate change, population growth, surface water withdrawal, and recreational pressures. These impacts diminish the ecosystem services a river can provide. The loss of ecosystem services can come at great expense to the communities that depend on them. These costs can be in the form of added water treatment needs, infrastructure maintenance, wildfire and flood recovery, road damage, reservoir in-filling – and even loss of life and property.
What does it mean to assess river health?
River health describes the ability of the river to perform its vital functions normally. Like people, river health can be good, poor or anything in between. River health is the outcome of its structural, physical, and biological integrity, which leads to the river’s ability to perform its valued roles and to resiliently deal with stress and disturbance. If a river’s health declines, the ecosystem functions and services it provides similarly decline. This creates a multitude of problems for the organisms that rely on the river and for the human communities that benefit from it.
In both ecosystems and organisms, health and functioning are paired concepts. A healthy system is one that is functioning in accordance with its environment. The CoRHAF is a functionally-based health assessment that conveys information about the condition of, and inter-dependencies between, many different components of the river ecosystem. Importantly, CoRHAF helps relate the effects that existing stressors have on individual components of the river system and how management and intervention could affect the future health and resilience of the river.
The CoRHAF follows a process that parallels human health assessment. A river ecosystem, like a human body, can be broken down into a system of interrelated components. Where human health is a culmination of the composite condition of the cardiovascular system, the nervous system, the respiratory system, etc., river health is a reflection of the composite condition of flow regime, sediment regime, riparian habitat, and so on.
Medical exams use tests of varying intensity to evaluate the condition of the human body, depending on the circumstances. A basic checkup may be limited to observations of heart rate and skin color, or supplemented by quick measurements such as blood pressure or reflex sensitivity. In other cases where the root causes of an observed sickness or injury are sought, more complicated procedures, such as an MRI scan or blood tests, may be carried out. In a similar manner, river health assessments can employ varying degrees of analytical intensity in response to the study circumstances or local concerns about a specific stressor to river health. At their simplest, assessments can be completed remotely using literature reviews, aerial imagery, and GIS tools. This desktop information can be supplemented with results from rapid field surveys. In other cases, intensive quantitative modeling or environmental sampling may be required to meet the study needs.
At the conclusion of a medical exam, a physician synthesizes all the information available (e.g., blood work, x-rays, etc.) and renders a clean bill of health or a diagnosis based on their interpretation of the data. In forming an expert opinion, a physician leans on guidelines of stage or grade that help describe the severity of an ailment. River health assessments can make use of the same approach where drivers of river health are examined, assessment results are interpreted by experts, and then conditions are rated with reference to established grading guidelines.
