In the arid sky islands, water is a precious resource for all life. Watersheds are anchored by riparian areas and include the upland landscape that drains to that particular river or drainage. Wild natural watersheds and river valleys of the Sky Islands are often impacted by human activities that fragment and disrupt ecological processes and deplete natural resources. Diminished plant cover leads to drying and highly erodible soils; subsequent precipitation carves ever-deepening wounds on the landscape. These impacts are exacerbated by changing patterns of temperature and precipitation. Combined with decades of fire suppression, many watersheds are also in a situation where catastrophic wildfires are scorching the forests and irreplaceable soil is washing away down mountain streams and gullies.
Watersheds are discrete functional units. Actions in one part of the system can affect the rest of the watershed. We work with federal and state agencies, private landowners, and conservation groups to address watershed health “from the top down,” that is, in a systematic way to ensure our work benefits the whole watershed as well as critical water sources such as springs. Some of the most important riparian areas of the region are bi-national – the Santa Cruz and San Pedro rivers flow through Mexico and north into the Arizona sky islands.
Restoration program staff and our corps of capable volunteers use low-tech approaches to improve watershed health:
- We use onsite materials such as rocks and brush to create structures to stop and prevent erosion issues.
- We install native plants that enhance wildlife habitat and help anchor the soils.
- We protect and restore seeps and springs that are valuable water sources for wildlife.
- We partner with landowners to exclude livestock from sensitive riparian areas.
Our goal is to keep the soil and the water on the landscape and in the watershed, where it will recharge groundwater and benefit native plants and wildlife Our work also keeps these special places intact for quiet recreation such as wildlife viewing.
Aravaipa Creek, a tributary of the San Pedro River, is a riparian oasis located at the north end of the rugged Galiuro Mountains, about 50 miles northeast of Tucson. It is truly a surprise and delight to enter the canyon, after traveling a few hours across arid deserts and rangelands to get there. You are greeted with a verdant canopy of large cottonwood trees and a creek of cool rushing water that is home to nine species of native fish and over 200 species of birds. The cliffs that tower above are home to bighorn sheep, raptors, and mountain lions. This wild area includes over 19,000 acres of Wilderness managed by the Bureau of Land Management (BLM), as well as The Nature Conservancy’s (TNC) Aravaipa Canyon Preserve, which flanks both the west and east ends of the canyon, as well as land along the south rim.
We have been working with the BLM and TNC on watershed restoration actions in the canyon and its tributaries since 2010. Ultimately, the goal of this collaboration is to increase both the amount of water stored in the soil and the length of the creek with year round flow.
- We plant native grasses to slow water down, giving it a chance to sink into the soil.
- We install simple structures made of natural materials to halt erosion and down cutting in tributary channels.
- We close unnecessary roads and make them natural areas again.
- We assist with the transformation of retired agricultural fields from dusty, weedy disturbed areas to fields where native grasses are grown to make weed-free hay that uses significantly less water than the original crops.
We are working with The Nature Conservancy in Aravaipa Canyon to remove dense infestations of an invasive ornamental plant, vinca (Vinca minor, also known as periwinkle), from the understory of the riparian forests. Originally from Europe and introduced here in the 1700s, its attractive purple flowers and dark leafy foliage have made it a very popular garden plant. This plant “takes over” in the shade of the trees, crowding out a diversity of native plants that would otherwise be thriving in this riparian oasis. Vinca has invaded many acres of the understory, limiting wildlife habitat over an extensive swath of the canyon floor.
We look forward to an understory that is free from vinca and that has native flowering plants that will support pollinators and provide resources for birds and other wildlife. It will take several years and an army of volunteers to manually remove these invasive growths, but we are up to the challenge!