Any river runner will tell you that the prime time of year for boating in the west is late spring, when rivers swell with runoff from melting snowpack. Spring runoff also plays a critical role supporting a healthy riparian ecosystem. Sandwiched between Glen Canyon and Hoover Dams, this section of the Colorado River is highly regulated by water sharing agreements between Upper and Lower Basin states and regional hydropower needs. While operational guidelines make the Grand Canyon boatable year-round, they also erase the natural seasonality of the river’s flow, disrupting the ecological processes critical to the health of birds, fish, and other riparian dependent wildlife
Every day 8,000-14,000 cubic feet per second (cfs) flows through Glen Canyon Dam’s hydropower turbines, meaning that boaters normally experience a consistent flow throughout the trip regardless of launch date. However, because of planned dam maintenance, we had a different experience—one with flows that mimicked natural seasonality on a dampened scale. For the first five days, operators ratcheted the releases down to 4,000 cfs in order to complete needed maintenance on the concrete apron below. Ecologically this simulated the low flows that occur in winter months—when sediment and nutrients accumulate in the river bottom environment, and benthic activity slows down. Similarly, our trip started out with a slower, lazier feeling. The rapids were bonier, but with less water in the channel, the current was slower, and we spent our first five days easing into the Grand Canyon at a relaxed pace.
Capitalizing on the need to ensure total monthly flow to the Lower Basin was not reduced by the maintenance low flows, scientists worked in advance, with dam operators to design a subsequent high flow release that would achieve ecological benefit. For the following five days, releases gradually ramped up to 20,000 cfs. These floodwaters were like a refresh button for the ecosystem—scouring the river bottom to clean substrates and release nutrients, stimulating insect production, and rewetting and burying seeds that would germinate native plants in floodplain. These processes stimulate food web production critical for birds, fish, and other riparian-dependent wildlife. For us, it was game time—the river was up, rapids were bigger, and we were moving faster. After five days of high water and excitement, we returned the normal 8,000-14,000 cfs flow for the remainder of our trip.
Environmentally driven high flow releases from Glen Canyon Dam have occurred only eight times in the last 25 years. This year was the first spring high flow release since 2008. High flow releases occurring in the fall move sediment to rebuild beaches, while spring ones stimulate biological processes and food web growth. The dam’s operating plan allows up to 25,000 cfs to be released under normal operations, but this experimental spring release was limited to 20,000 cfs to maintain maximum hydropower generation—a reminder that environmental considerations are not top priority in Colorado River water management.
The traditional narrative that environmental water needs are at odds with people and agricultural needs has heavily influenced Colorado River policy and management in the past. In the coming years, Colorado River water managers have the opportunity to elevate environmental considerations alongside recreational, urban, and municipal needs as they re-negotiate the Interim Guidelines, which define federal policy for operations at the Glen Canyon and Hoover Dams, as well as shortage sharing rules. The existing Interim Guidelines expire in 2026, and people are already discussing what the next version will look like. The University of Utah’s Future of the Colorado River Project recently finished an evaluation of alternative management strategies for the river in anticipation of the upcoming renegotiations. They concluded that while changing dam operations will not solve the ongoing challenge of water demand exceeding water supplied by the Colorado River, they could be re-designed to yield more environmental benefits. The recent high flow releases from Glen Canyon Dam are a perfect example of how operations can be adapted to benefit the environment without sacrificing supply to water users downstream.
It was both special and exciting to experience such a variety of Colorado River flows on my trip. It also gave me a glimpse into the potential changes we might see in future river operations. Our work to protect water supplies for birds and people is critical as the Colorado River Basin becomes warmer and drier. In the coming years we must continue to search for creative solutions that yield benefits for water users and the river itself, and reinforce the idea that environmental, agricultural, and people water needs do not have to be at odds as future Colorado River operations are negotiated.