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Fifty Years of Instream Flow: What it’s Taught Us, and Why We Love it

Mar 19, 2024

Fifty years ago, America was experiencing an environmental awakening with the passage of the Clean Air and Clean Water Acts by Congress. Here in Colorado, state decision makers radically altered the landscape of state water law by introducing an Instream Flow program, allowing the state to acquire water rights to benefit the environment, keeping water in streams and rivers. The program has been enormously successful, appropriating 2,200 water rights along 1,700 stream segments, the collective force of which have protected 9,720 stream miles.

Instream flows (ISF) do more than keep our streams and rivers healthy — they provide built-in resilience to drought and wildfire, allowing for greater elasticity in the dry years that have recently plagued the entire Western region. Flows help endangered species by stabilizing habitats, and benefit not just the stream itself, but the surrounding landscape and vegetation. Water flowing in rivers from the ISF program has even been shown to improve water quality and lower the prevalence of harmful sediments. It also has proven economic benefits, and helps drive Colorado’s $19 billion recreation economy (it’s hard to catch a fish in a dry river!).

The history of Colorado’s ISF program is fascinating. Following the drumbeat of the environmental movement and many environmentally-oriented pieces of legislation from the 60s and 70s (including the Wilderness Act, Wild & Scenic Rivers and Endangered Species Act as well as and the establishment of both Earth Day and the Environmental Protection Agency), the 1973 legislation to establish ISFs as a legitimate water right in Colorado constituted a famously unlikely alliance between traditional water users and environmentalists. (It was once described as an “unholy alliance” by then-CWCB director Felix Sparks, who had also once claimed a potential ISF program was “utterly impossible” before helping to implement it). The alliance reflected a growing anxiety about the degradation of natural systems — especially in the Roaring Fork Valley and the Arkansas River Basin — and sought to rectify the fact that, as a prior appropriation state, there was little Colorado could do under existing water law to keep water in rivers for the sake of the rivers themselves. 

The ISF program has evolved over the course of time, creating greater flexibility, removing limitations, and establishing a source of funding to purchase water rights instead of relying on donations and appropriations of new water rights that are junior and therefore lower in priority to other water rights (as it had for the 36 previous years). It has expanded to be an explicit aid during drought emergencies, by allowing loans and leases of water to benefit the environment, and was enlisted to help bolster mitigation plans for endangered fish and wildlife along certain stream reaches. In 2020, two pieces of legislation again broadened the scope of what types of water rights could be used as an ISF, and how those rights could be acquired.

The Colorado River Drought Task Force, convened by the state last year, recommended further expanding the ISF program to allow water users to loan water stored in reservoirs to benefit a wider range of stream reaches. It might seem like a small change, but would be impactful. Charting more pathways for water users to temporarily lease or loan their water to keep rivers healthy and flowing without diminishing their water rights is an essential step in enhancing resilience in the face of less reliable water supplies.

So, looking back on the last fifty years, what can we learn from one of Colorado’s most important but most often overlooked tools for water management? The ISF program has helped maintain healthy river flows — essential to our state and region — resulting in cascading benefits for the state’s businesses, agricultural economies, communities, outdoor recreation, fish, and wildlife. Additionally, it has helped demonstrate the capacity for non-consumptive environmental needs to coexist alongside consumptive needs, such as diverting water for agricultural or municipal needs. Coloradans have often sought to pioneer the relationship between humans and their natural partners, and the ISF program is a prime example.

The unlikely alliance that made the ISF program happen a half-century ago has much to teach us about contemporary collaboration as the pressures on our water system and those who rely on it become more extreme. Coloradans have a proven ability to come together in pursuit of meaningful water solutions. The ISF program is, now, a staple of Colorado water management — a tool in our toolbox of resilience as handy and well-worn as a phillips head screwdriver — but at the time of its inception, it was experimental, controversial, highly-litigated, and completely revolutionary. It took a cohort of smart, determined people who disagreed on almost everything else to make it the success it is today — and from this, we can learn something that will surely serve us well in the challenging water conversations still ahead.

Watch this video from the Colorado Water Conservation Board to learn more about the history and necessity of the ISF program, and take some time this year – whether you’re river rafting, fly fishing, or enjoying a beer on the riverbank — to appreciate what this seemingly wonky, but fundamentally important program, has done for our state, its rivers, and its people. 

Press Release: Colorado River Basin Groups Advocate for Environmental and Resilience Priorities in Proposal to Bureau of Reclamation

Mar 29, 2024 -
March 29, 2024  Media contact: Annika Shamachar, [email protected]  Denver - Today, a coalition of conservation groups across the Colorado River Basin jointly...