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Shifting dehydrating, degrading ephemeral water channels to better-vegetated, rehydrating, agrading channels with Bill Zeedyk-directed efforts in Altar Valley, Arizona

By Brad Lancaster
with gratitude to Bill Zeedyk for his edits, feedback, and mentoring
www.HarvestingRainwater.com

Starting January 2012, Bill Zeedyk and Steve Carson directed the largely volunteer-installed on-the-ground work in a collaborative conservation/restoration project in the Altar Valley in southern Arizona, aiming to reverse the erosive down cutting of water channels/arroyos and dirt roads at the Elkhorn/Las Delicias Watershed Restoration Demonstration Project site by using three primary strategies:

• induced meandering within the water channel with one-rock-high baffles and one-rock dams seeded with native restoration seed mixes;

• treating a 3.25-mile stretch of dirt road with 54 rolling dips that drain stormwater off the roads and passively irrigate roadside vegetation, and 14 road crossing stabilization structures stabilizing road crossings of streams;

• upland restoration with one-rock high rock media lunas and one-rock dams upstream of the main water channel

The project and its effects were and are extensively monitored.

As Bill Zeedyk says, the intent of the project was to reverse the trend by shifting from erosion of soil to deposition of soil.

It has done that.

In addition, moisture now lingers longer in the watershed, enabling more vegetation to grow, better capture sediment, and hold and build soil. All this also reducing flooding and erosion downstream.

I just attended the 10th anniversary tour of the project, and wanted to share photos and videos taken over the years at the project, plus links to data from the project’s extensive monitoring, so you can see some of the positive results.

Work within one of the main water channels/arroyos

Media luna structures above the water channel (scroll down for photos) are also helping heal this part of the channel. The media lunas have helped slow, spread out, and infiltrate sheet flow in upper reaches of this water channel’s watershed to re-wet and re-vegetate about 2 acres of previously bare draining and eroding land.

By reducing the volume, depth, and speed of peak flow of stormwater (by spreading out the flow) within and above the water channel, the force and ability of the flowing water to carry sediment is also reduced. So, you then see more smaller particles of sediment compared to the larger particles seen before restoration work.

As the water flow is spread out and slowed down, more water saturates the soil, and prolongs the length of the time the water flows and lingers in the landscape, enhancing the growth of more water-slowing and -spreading vegetation.

As more vegetation grows, the roots increase the permeability of the soil, which then increase the volume of water that infiltrates the soil — especially within the site’s otherwise hard, exposed subsoil. Vegetation continues to grow, and sets is roots deeper and deeper as it also grows a thicker and more absorptive sponge of organic matter above the soil’s surface; more water is slowed and infiltrated, and more vegetation grows—a beneficial feedback loop.

Healthy reference reach in Altar Valley, photo taken 10-18-2008; though note that the watershed of this creek/arroyo is much larger than the creeks/arroyos that were treated in the project.
When assessing the Elkhorn/Las Delicias Watershed Restoration Demonstration Project site and planning potential interventions, local healthy watersheds and healthy reaches of water channels, such as this one, were sought out and studied, as a guide for what used to be pre-erosion, and what to aim for with restoration.
Note here how wide the channel is, and how the adjoining vegetated floodplain is still within easy access for large flow events to spread out onto and hydrate more of the larger watershed. A lot of the water flow is probably subsurface, within the pore spaces of the sediment and soil, especially after surface flow subsides.
Photo: Brad Lancaster
Channel 21, photo taken 1-15-2012 just after construction.
This rock structure on the downstream side of the dirt road crossing the channel has raised the bed of the channel on its upstream side.
Footer rocks at the base of the downstream side of structure reduce erosive scour caused by water flowing over and off the structure.
Structure built by Steve Carson of Rangeland Hands, Inc.
Channel 21, photo taken 1-15-2012.
Downstream of the rock structure stabilizing the road crossing, is a one-rock dam (ORD). The ORD raises the brim of the scour pool that will form at the base of the road-stabilizing rock structure as the water falls off the steep downstream side of the structure. After raising the brim of scour pool, the ORD will also keep the elevation of the surface of the pool constant, reducing scour (the pooled water will diffuse the force of the water falling into it), while also enabling the pooled water to linger longer post-rain (benefiting wildlife and livestock).
Photo: Brad Lancaster
Channel 21, photo taken 10-24-2016.
This rock structure on the downstream side of the dirt road crossing the channel has stopped the erosion of the road and channel bed, and enabled significant vegetation establishment, especially on its upstream side where the channel and water flow is now much wider, and slower, enabling more moisture to infiltrate the accumulating sediment.
There is some erosive side cutting from water flow cutting around the sides of the structure, but this can be easily fixed by adding more rock on the sides, and raising the elevation of that rock, so more of the flow is focused to the lower, middle section of the structure.
Photo: Brad Lancaster
Channel 21, photo taken 2-4-2022
Sometimes Bill Zeedyk likes to create or enhance ephemeral pools of water with a cross-vane structure that concentrates flow to the center of the channel where there is more drop due to existing conditions (such as the large boulder around which the structure was built), and force from the falling water to scour a pool within the channel.
A one-rock dam on the downstream side helps catch sediment scoured from the pool, while also deepening the pool, and controlling the grade/elevation of the channel bed so the falling water does not undercut the cross-vane structure.
These structures must be maintained over time. Here, some of the anchoring rocks on the downstream side of the one-rock dam have flowed away. I replaced the missing rock with larger rock after this photo was taken.
Note that maintenance is not always necessary if large enough rock (which will not move) is used, the rock is of good composition, and the quality of the work is good and robust.
Compare to next photo of a different cross vane installation photographed in rainy season.
Photo: Brad Lancaster
A cross-vane rock structure (keyed into bedrock on left side of photo and native boulders on the right) controlling a headcut that used to erode the edge of road. The structure also purposefully creates a scour pool that clears sediment and collects water for wildlife, people, and livestock.
Rock work moving up the banks, and curved downstream, lessens depth of water along banks, reducing the water flow’s erosive force, which might otherwise erode around the structure.
Water spilling over ends of the structure (in big flow events), along the creek banks, is directed into the pool below the structure. The pooled water diffuses the force of the incoming water, while enhancing water availability for wildlife and livestock.
Designed by Bill Zeedyk. Hand-built by Pima County road crew in 2007. Altar Valley, Arizona.
Reproduced with permission from “Rainwater Harvesting for Drylands and Beyond, Volume 1, 3rd Edition.”
Water flows perpendicular to what it flows over.
Thus, this shape (used in a cross-vane) helps direct water to the center of the channel.
Reproduced with permission from Rainwater Harvesting for Drylands and Beyond, Volume 2, 2nd Edition

More on harvesting water from dirt roads with rolling dips
See here for images and more

Work upstream of the main channels

The topography, in the four photos immediately above, is typical of what the valley floor looked like before headcut erosion and resulting gullies arrived and drained the valley.

The erosion was due to severe overgrazing, which removed much of the vegetative cover of the land, which then sped up the flow, depth, and force of the water draining off the land. Other practices that similarly drained and dehydrated the land were irrigation diversions and railroad embankments that channelized sheet flow; dirt roads that diverted, captured, and channelized sheet flow; and fire suppression.

The main channel of the Altar Valley Wash (downstream from these photos) then erosively down cut, and all tributaries draining into the down cut Altar Valley Wash then also down cut—starting at headcuts formed where water flow from the tributaries dropped over a newly steepened drop into the recently down-cut Altar Wash. The whole Altar Wash and its tributaries throughout the Altar Wash watershed down cut and head cut up valley.

So, the four photos above, show a relic of what the landscape would’ve looked like without gullies. Though it would’ve been better vegetated.

Erosion caused by wagon roads is what really caused the whole system to originally degrade, plus there was an irrigation dam upstream in the Altar Wash that blew out in the early 1900s. When it blew out, flows got caught in the wagon wheel ruts that were paralleling the water channel. Ruts were straighter than the meandering channel so the paths of the ruts were steeper, water flowed faster within them, and easily carried away the fine clay soils. This started the whole unravelling.

It was made worse by the irrigated pastures on the ranch that is now the Buenos Aires Wildlife Refuge.

Due to erosion from road and irrigation ditches, head cutting and down cutting started (due to main channel being incised) and this head cutting and down cutting continues to this day.

It is hard to prioritize where to do grade control work in the watershed, since there is such a large need throughout.

So, at least encourage restoration work wherever it is welcomed by the land owner, manager, volunteers, etc. Such work could be on the refuge or any of the ranches where channel incision is still occurring.
For as Bill says, “You can lead people, but you can’t push a rope.”

Videos of the project

See here for part one video

See here for part two video

For more information

• See the Altar Valley Conservation Alliance website at:
https://altarvalleyconservation.org/

For more info specific to their Elkhorn/Las Delicias project see:
https://altarvalleyconservation.org/our-work/conservation/projects/elkhorn-las-delicias-watershed-restoration-demonstration-project/

GIS analyses for 10-year evaluation


• See Bill Zeedyk’s books:

Let the Water Do the Work: Induced Meandering, and Evolving Method for Restoring Incised Channels

A Good Road Lies Easy on the Land: Water Harvesting from Low Standard Rural Roads

Note that Bill Zeedyk and Steve Carson use the book in workshops for County dirt road crews. Such workshops should be ongoing.

Want to meet, work with, learn from Bill Zeedyk?

Stay current with the Altar Valley Conservation Alliance events

and

the Albuquerque Wildlife Federation—especially its events/restoration projects at Fort Union Ranch in northern New Mexico—Bill will be there!

  • and read…

See the new, full-color, revised editions of Brad’s award-winning books
– available a deep discount, direct from Brad:

Book Cover #1

Volume 1

Especially…

appendix 1: Patterns of Water and Sediment Flow with Their Potential Water-Harvesting Response

Bill Zeedyk helped me develop this section of the book.

Buy the Book Now
Book Cover #2

Volume 2

Especially…

chapter 7 for rolling dips used to harvest water off dirt roads in Altar Valley and elsewhere.

chapter 10 for numerous in-channel strategies including one-rock dams, sheet flow collectors, sheet flow spreaders, rock-mulch rundowns, and induced meandering.

Bill Zeedyk shared extensive information and editing for these chapters.

Buy the Book Now
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