Dye Tracing

Water is one of Grand Canyon’s most precious resources. Springs, seeps, and groundwater sustain wildlife, support riparian ecosystems, and provide drinking water for visitors and park operations. Yet much of this water moves invisibly beneath layers of rock, making it difficult to understand where it comes from, where it goes, and how it may be affected by development, drought, or contamination.

Dye tracing is one of the most powerful tools scientists use to uncover these hidden connections. By introducing environmentally safe dyes into sinkholes, fractures, and recharge zones on the rims, researchers can track how groundwater flows through the canyon and which springs it supports below.

As the official nonprofit partner of Grand Canyon National Park, Grand Canyon Conservancy supports dye tracing research that provides the science needed to protect the park’s water for generations to come.

Why Groundwater Research Matters

Groundwater systems at Grand Canyon are shaped by complex geology: layers of rock, fractures, and faults that make water movement difficult to predict. 

Without scientific study, it is challenging to understand:

• Where spring water originates
• How surface activities affect groundwater
• How long water takes to move through underground systems

This knowledge is critical for protecting drinking water, preserving sensitive ecosystems, and ensuring that development and visitor use do not unintentionally harm the canyon’s fragile hydrology.

How Dye Tracing Works

In dye tracing studies, scientists introduce a non-toxic, environmentally safe dye into a water source such as a sinkhole or infiltration area. Monitoring equipment is then placed at springs and water outlets to detect when and where the dye appears.

This process helps researchers:

• Identify groundwater flow paths
• Measure travel times between recharge areas and springs
• Understand connections between surface water and groundwater

All dye tracing work is carefully planned to protect water quality, ecosystems, and visitor safety.

To learn more about our scientific research, visit our Scientific Research Page

What’s Been Completed

Thanks to Grand Canyon Conservancy support! 

In 2025, Grand Canyon Conservancy-supported dye tracing reached a major milestone.

The second round of the North Rim Dye Trace Study was completed, with:
• Dyes injected into two North Rim sinkholes
• 43 springs and stream sites monitored across the canyon
• Tracking of five different dyes injected in 2024 and 2025

Over the past two years, this effort involved 858 staff field days, including scientists, park staff, volunteers, and Northern Arizona University students. Four of the nine core Geosciences staff were hired through a partnership between Grand Canyon National Park, American Conservation Experience (ACE), and Grand Canyon Conservancy.

This project is now the largest dye trace study ever conducted in North America and is already providing critical insights into:
• Groundwater flow paths
• Connections between surface areas and drinking water
• How wildfire, including the Dragon Bravo Fire may affect canyon springs

June 2026 Update:

Food-grade, fluorescent dyes were injected into three sinkholes on the North Rim in April 2024 and into two sinkholes in March 2025, prior to snowmelt. Three of these five sinkholes were repeated injection sites from those in 2015-2017 to determine consistency of source areas, flow paths, and flow rates from year to year.

Charcoal dye receptor packets were placed at 43 spring and stream sites in the canyon two months prior to the 2024 injection and were exchanged every 3-8 weeks through the fall of 2025 to determine if, when, and where dyes emerged. Packets continue to be exchanged through 2026, but at a lower frequency (every 4-6 months). Charcoal is an adsorber, so dye dissolved in water will come out of solution and accumulate on the dye receptor. Charcoal dye receptors can therefore indicate the presence or absence of dye at the site where they are placed, and the exchange of receptors indicates how long the dye remains detectable at a site. This now 2.5-year-long field effort has been conducted by a team of 10 staff in the GRCA Geosciences Program, GRCA staff in other Programs and Divisions, multiple volunteers, and Northern Arizona University students, totaling 950 staff field days, 55 helicopter hours, and over 550 dye receptors.

Results

The most current results are shown below in the 2024, 2025, and 2026 maps. Eosin and RWT were injected into two different sinkholes in April 2024. Eosin was first detected at Roaring Springs in May 2024 and has continued, on and off, into 2026. RWT was first detected at two springs in upper Bright Angel Creek (BAC) and at downstream sites in May 2024, and it has persisted for over 2 years. RWT was also detected in Roaring Springs in April 2025 and has continued on and off for almost a year. SRB was detected at the same two springs in upper BAC and downstream sites starting in May 2025 and continued for 6 months. SRB was also detected more recently in Shinumo Creek, starting in July 2025 and continuing for 2 months. These positive detections have continued well past the snowmelt pulses and into baseflow. To date, there have been no detections of Fluorescein or of Pyranine.

Dye detections occurring continuously and even on and off through baseflow support previous evidence that some annual snowmelt exits springs immediately, while a portion enters long-term groundwater storage. There is also new evidence that flow paths, flow rates, and source areas may change from year to year, as repeated injections into Fuller Canyon Sink revealed different results in 2024 than they did from the previous dye trace in 2017. RWT injected in Fuller Canyon Sink in 2024 took over a year to show up at Roaring Springs, but dye injected in the same sinkhole in 2017 took only a month to show up at Roaring. Dye injected there in 2024 also showed up within a month at two other springs in BAC, but dye injected there in 2017 only showed up at Roaring Springs. Additionally, delayed detections of RWT at Roaring Springs and of SRB in Shinumo Creek alongside immediate detection of RWT and SRB at other springs indicate different travel times for the different flow paths connecting a single sinkhole to multiple springs.

Satellite and game camera imagery of snowpack on the North Rim and the earliest detections of dye at springs indicate the fastest travel time from infiltration to discharge, anywhere from 2-26 days, and the longest travel time of at least 369 days. The timing, location, and duration of dye detections will be compared to dye detections from 2015-2017 and analyzed alongside multiple years of snowpack and groundwater flow data to outline source areas for Roaring Springs and Bright Angel Creek, compare how flow paths and source areas may change across different snowpack conditions, and calculate annual water budgets at springs. Approximate flow paths, shown as dotted arrows on these maps, will also be refined using results from a project mapping caves and structures in the canyon (Lasala et al., In Press). The results of these additional analyses will then be used to forecast groundwater vulnerabilities from climate change and contamination. Dye receptors will continue to be exchanged every 4-6 months and analyzed for all five dyes through 2026 and into 2027, depending on continued detections.

Planned Efforts Include

• Preparation of a detailed scientific report for donors and park leadership
•  Launching the next phase: Canyon-Wide Spring Monitoring, a long-term effort to understand groundwater health across the entire park

This next phase represents a $6 million, 13-year scientific initiative, with an immediate goal of securing funding for the first year of expanded monitoring and analysis.

How Grand Canyon Conservancy Supports Dye Tracing

Grand Canyon Conservancy provides philanthropic support that makes this groundbreaking groundwater research possible, including:
• Field teams, equipment, and river missions
• Scientific analysis and reporting
• Partnerships with American Conservation Experience, Northern Arizona University, and National Park Service scientists
• Long-term planning for canyon-wide water protection

Donor support directly helps protect the springs, streams, and groundwater that sustain life throughout Grand Canyon.

Why This Work Matters

Every spring tells a story about where water comes from — and whether it is safe. Dye tracing gives scientists the tools to read that story and ensure that Grand Canyon’s water remains protected, even as climate, development, and visitation change.

By supporting dye tracing, you help safeguard the hidden water systems that make the canyon possible.

Frequently Asked Questions

Why are springs so important at Grand Canyon?
Springs provide critical water for wildlife, support ecosystems, and hold cultural significance, making their protection essential.

Is dye tracing safe for water and wildlife?
Yes. The dyes used are non-toxic and carefully regulated to protect ecosystems and water quality.

Why is groundwater difficult to study?
Groundwater flows underground through complex geological formations, making it impossible to observe without specialized research methods.

How does dye tracing support conservation decisions?
The data helps managers understand water connections and make informed decisions about protecting springs and groundwater resources.