Springs, Seeps and Hanging Gardens: The Small Waters of Glen Canyon

Lake Powell holds a great deal of water, but most of Glen Canyon National Recreation Area is rugged desert where water is scarce and hard to reach. Springs and seeps, with tinajas and streams, are small but vital water sources scattered through it, and the plants and animals that depend on them need them to last.

Springs, seeps and hanging gardens

A spring brings groundwater to the surface; a seep yields water underground that does not always reach it. Their water matters most in drought, when the snowmelt and rain that feed streams and tinajas can shrink or vanish.

Glen Canyon's springs take many forms: rising in stream channels, emerging from slopes, making wetlands and pools, and forming hanging gardens, where water trickles from a horizontal crack in a cliff and over time carves a cool, sheltered alcove. Hanging gardens are common on the Colorado Plateau but rare elsewhere in the country, and after his 1869 expedition John Wesley Powell named Glen Canyon for these large alcoves, or "glens." Lake Powell drowned most of the ones he saw along the Colorado River, but Glen Canyon still has some of the plateau's finest. More than any other kind of spring, hanging gardens are hotspots of biodiversity and home to rare plants.

A hanging garden in an unnamed canyon off Lake Powell near the San Juan River confluence. NPS.

Threats

• Less groundwater, from smaller snowpacks, changing rainfall or pumping, means less water from springs.
• Higher temperatures evaporate more water; in severe droughts some springs may dry up.
• Exotic plants crowd out natives — a particular problem for species that live only at springs.
• Livestock grazing, an important cultural resource permitted on about 60% of the park, brings trampling that damages plants and fouls water.
• Pollutants from the air or runoff, and disturbance from erosion and recreation, affect water quality.

The assessment

A Park Service Natural Resource Condition Assessment of water resources away from Lake Powell and the main Colorado River made springs and seeps one of five focal resources — the first parkwide assessment of them at Glen Canyon. Utah State University ecologists drew on published and unpublished reports, online databases and the park's springs database, sorted the springs by type, geology and watershed, evaluated plant health and threats, and compared water quality at 12 springs livestock can reach with 12 they cannot.

What they found

• How many. 250 springs confirmed by at least one visit, mostly in the Navajo Sandstone and Kayenta Formation, plus hundreds of possible but unconfirmed springs in the Escalante watershed.
• Plants — good news. Native plant communities are in relatively good shape. Surveys at 185 springs recorded 144 native species: 93% of Glen Canyon's and 66% of the Colorado Plateau's recorded wetland species. Springs forming pools, wetlands or hanging gardens had the most species, and most springs had fewer than three non-native species.
• Condition — fair. Of 29 springs assessed, 65% were intact and in good condition, threatened mainly by non-native plants, drought and flooding; cliffs keep many out of reach of people and livestock. Another 24% showed some disturbance and decline, and 7% were degraded, with livestock trampling, grazing and water structures adding to the damage.
• Water quality — too soon to say. Baseline data exist for some springs, but more are needed. Temperature, pH and dissolved oxygen were similar whether or not livestock could reach a spring. Specific conductance was higher where they could, but some springs are naturally high, so the cause is unclear.

Eastwood's monkeyflower (Mimulus eastwoodiae), an endemic plant of Glen Canyon's springs and seeps. NPS.

What managers can do

The findings can inform any park plan that touches springs or the groundwater feeding them — and above all show that the park needs more information. Managers began long-term monitoring of about 20 hanging gardens in 2019. Open questions: how climate change will alter the amount and quality of spring water and the life it supports; whether livestock or erosion threaten springs and how management should respond; when mineral extraction affects them; and whether airborne contaminants such as heavy metals or nitrogen should be monitored.

The park's natural resource team measuring discharge and water quality at a spring in Four Mile Canyon. NPS.

What you can do

• Watch your step: don't trample the delicate plants at springs, seeps and hanging gardens.
• Soap, sunscreen, bug spray and other products pollute the water — don't swim in springs or wash near them.
• Camp, cook and wash dishes away from springs; Leave No Trace advises staying at least 200 feet from springs and other small waters, so the soil can filter. Glen Canyon has its own backcountry camping rules to protect water sources.

Sources

• National Park Service, "Small Water, Big Impact: Assessing the Health of Springs, Seeps, and Hanging Gardens," in the series NRCA 2022: Condition of Glen Canyon's Tributary Rivers and Associated Resources. https://www.nps.gov/articles/000/nrca_glca_2021_springs.htm
• J. Albright and others, Natural Resource Conditions at Glen Canyon National Recreation Area, Natural Resource Report NPS/SCPN/NRR—2022/2374. https://doi.org/10.36967/nrr-2293112
• Corrected: the page calls specific conductance "an indicator of dissolved solids and murkiness"; it measures dissolved solids, not murkiness.