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Section 319
NONPOINT SOURCE PROGRAM SUCCESS STORY
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Restoring and Stabilizing Stream Channel Improves the Lower Rio Blanco
Waterbody Improved
The San Juan-Chama Diversion Project (opened in 1971)
had led to reduced water flow and a loss of aquatic habitat
in Colorado's Rio Blanco, a tributary to the San Juan River. As a result, n 1998 Colorado
included a 12-mile reach of the Lower Rio Blanco on the state's Clean Water Act (CWA)
section 303(d) list of impaired waters for failing to support its aquatic life designated use due
to sediment. Project partners restored the stream channel to match the altered flow regime
and educated landowners. These efforts restored the river's physical and biological function
and improved water quality, prompting Colorado to remove the Rio Blanco, including the
12-mile reach of the Lower Rio Blanco, from the state's list of impaired waters in 2008.
Problem
The Rio Blanco originates in the San Juan
Mountains. It flows for 30 miles through the San
Juan National Forest and private lands to its
confluence with the San Juan River in southwest-
ern Colorado (Figure 1). The state classifies the
Rio Blanco as an Aquatic Life Coldwater Class 1 f
Recreation Class 1 waterway supporting water sup-
ply and agricultural uses.
in 1971 the San Juan-Chama Diversion Project
opened, diverting 70 percent of the Rio Blanco's his-
torical flow to supply water for municipal, domestic,
industrial and other uses. A basin summary prepared
in 1990 by the U.S. Forest Service found that the
diversion and land use practices (including livestock
grazing, irrigated pasture, recreation and domestic
activities associated with low-density urban develop-
ment) had negatively affected the Rio Blanco, includ-
ing a 12-mile reach of the Lower Rio Blanco, from
the Blanco Diversion Dam for the San Juan-Chama
Project to its confluence with the San Juan River
The diversion and land use practices had created a
wide, shallow stream with very little pool and cover
habitat (Figure 2) Water temperatures were high,
exceeding the lethal limits for trout (77°F to 81°F) In
addition, flow changes and streambank erosion had
altered the riparian zone and led to sediment loads
that exceeded the stream's transport capacity.
Figure 1. The Rio Blanco watershed is in southwestern Colorado.
Colorado's sediment water quality standards
require that waters be free from bottom deposits
detrimental to beneficial uses. Because of the loss
of aquatic habitat resulting from the construction
and operation of the San Juan-Chama Diversion,
in 1998 the state placed a
12-mile reach of the Lower
Rio Blanco on Colorado's
iist of impaired waters for
failing to support its aquatic
iife use due to excessive
sediment deposition.
Restoration was completed
and the stream returned to
meeting standards before
a total maximum daily load
was developed.
Figure 2. Before restoration, water
diversion and land use activities
caused the Lower Rio Blanco to be
wide and shallow.
Blanco Tunnel
yMiddle'Rio Blancoj
Watersheds
140801010304
Lower Rio Blanco
Watersheds
W408ft10l'oS06v
- Rio Blanco
Watersheds
Legend
Clean Water Act Section 319 Project Locations
State Highway 84
Rio Blanco Watersheds
Water Diversion Location ¦
State Highway 84
0	0.75 1.5	3 Miles
	1	i	i	i	I	i	i	i	I

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Project Highlights
Results
The Rio Blanco River Restoration Project was
the Colorado Department of Public Health and
Environment's first CWA section 319-funded project
aimed at addressing hydrologic modifications.
In 1999, project partners—the Colorado Water
Conservation Board, the Lower Blanco Property
Owners Association and other partner agencies—
implemented a stream channel restoration dem-
onstration project on a 1.1-mile reach of the Lower
Rio Bianco. The project partners implemented a
number of best management practices (BMPs) to
stabilize the stream channel, including
•	Fortifying the streambanks by installing grade
control structures and native material revetment
(permanent structures composed of natural
materials to protect eroding banks)
•	Deepening the channel to decrease the stream
width-to-depth ratio, which in turn decreases
water temperature and improves the river's sedi-
ment transport capacity
' Restoring stream
meanders, which offers
greater physical stability
I Installing rock weirs
(channel-spanning rock
structures) and cross
vanes to redistribute the
stream energy away from
the banks and toward
the center of the stream
(Figure 3).
Figure 3. Project partners installed
cross vanes and other stream
channel stabilization BMPs.
Because a mixture of private and public lands
surround the Lower Rio Blanco, project partners
collaborated extensively with local landowners and
partner agencies. A series of meetings expanded
on existing watershed-wide efforts to address
stream flow and water quality issues in the basin
and involved individual landowners in the water-
shed planning process.
CWA section 319 funds supported an additional
stream restoration project to continue channel
stabilization efforts on the Lower Rio Blanco in
2001. in 2002 additional section 319 funds were
used to repair flood damage to the newly installed
BMPs. in total, project partners conducted stream
channel restoration on approximately 3.25 miles of
the Lower Rio Blanco.
The channel reconfiguration and bank stabilization
efforts were designed to improve the natural ability
of the river to transport sediment and maintain fish-
ery habitat, despite reduced flow in the lower river
reach. Project partners restored natural meanders
and riffle-to-pool ratios and achieved a healthy
width-to-depth ratio, allowing the river to flush fine
sediment that had been smothering the substrate
(including aquatic insects and fish eggs), thereby
improving aquatic habitat. Pool depth increased
from as little as 0.5 inch to 6 to 7 feet, providing
year-round trout habitat.
Post-project monitoring conducted by the
Colorado Division of Water Resources showed
marked improvements in sedimentation, tem-
perature, and dissolved oxygen levels, as well as
greater aquatic insect diversity and abundance. On
the basis of these data and evident improvements
in the physical conditions and biological health of
the river, Colorado determined that the restored
reach fully supports its aquatic life designated
use. As a result, the state removed the Rio Blanco,
including the 12-mile segment of the Lower Rio
Blanco, from the impaired waters list in 2008.
Partners and Funding
Restoration partners included the Colorado
Water Conservation Board (project coordinator,
technical assistance); the Colorado Division of
Wildlife (in-kind match); the Colorado Division of
Water Resources (in-kind match); the San Juan
Water Conservancy District (lead sponsor); the
Southwestern Water Conservation District (match
and outreach); and the Lower Blanco Property
Owners Association (cash and in-kind match,
including innovative "Adopt a Rock" boulder spon-
sorships to help fund stream channel stabilization
efforts and chokecherry jelly sales).
Restoration efforts were supported by two CWA
section 319 projects ($329,537 total), $356,089
in matching funds from local and state partners,
and $70,000 in other federal funds (including
$49/000 from the U.S. Department of Agriculture's
Environmental Quality Incentives Program, which
supported stream restoration). An additional
$12,237 in CWA section 319 funds and $8,486 in
match funds also helped repair damage from flood-
ing before new BMPs were fully established.
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U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA 841-F-12-001YY
November 2012
For additional information contact:
Lucia Machado
NPS Program Coordinator
Colorado Department of Public Health and
Environment
Lucia.machado@state.co.us • 303-692-3585

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