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Water: Nonpoint Source Success Stories

Nevada: Martin Slough Water Quality Enhancement Project: Water Quality Improves in the Upper Carson River Basin

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Contact:
Mary Kay Riedl
Nevada Division of Environmental Protection
Nonpoint Source Management Program
775-687-4670 (ext. 3096)
mriedl@ndep.carson-city.nv.us
Primary Sources of Pollution:

urbanization

agriculture
Primary NPS Pollutants:

nutrients

fecal coliform bacteria

suspended solids

metals
Project Activities:

constructed wetland ponds

realignment of slough downstream

riparian restoration
Results:

reductions in fecal coliform bacteria, phosphorus, ammonia, and heavy metals

improved wildlife habitat

The Carson River in Western Nevada is a river in trouble. Natural phenomena like drought and flooding and human activities such as agriculture (irrigation return flows and livestock grazing), hydrologic modification (water diversion and channelization by the U.S. Army Corps of Engineers during the 1960s), habitat modification (removal of riparian vegetation), and urban runoff have contributed to degraded water quality, beneficial use impairment, and highly unstable, easily erodible banks. The river is listed on Nevada's 303(d) list for total phosphorus, suspended sediment, turbidity, and several metals. During the recent high water years of 1995 and 1997, hundreds of acres of land along the river were washed away. Not only were valuable land and riparian habitat lost, but the eroded material also degraded fish habitat downstream.

The towns of Minden and Gardnerville are located side-by-side in the heart of Carson Valley, Nevada, where ranching and associated irrigated agriculture dominate land use. The East and West Forks of the Carson River meet in the southern portion of the valley to form the main stem of the river. Scenic vistas surround the area: the Carson Range of the Sierra Nevada Mountains rises to the west, and the Pinenut Mountains border the eastern side of the valley. Through a public outreach process, Minden and Gardnerville have identified the Martin Slough as an important amenity to their communities.

The Martin Slough is a partially man-made waterway that flows through both communities before it joins the East Fork of the Carson River. Historically the slough was used to deliver irrigation water and collect return flow. However, because of rapid urbanization over the past decade, the Martin Slough has also become a conduit for increased amounts of urban runoff. Water quality monitoring has shown elevated levels of nutrients, fecal coliforms, suspended solids, and metals.

Joining forces to arrest runoff

In 1995 Minden and Gardnerville joined with the Douglas County Water Conveyance Advisory Committee, Douglas County School District, and local landowners to develop a plan to improve water quality, restore wetland and wildlife habitat, provide for ground water recharge and storm water storage and treatment, provide for public education, and preserve an open-space corridor through both communities.

The entire project consists of six phases. During Phase 1 of the project, completed in September 1999, two wetland ponds were constructed in the upper slough to provide for water treatment and sediment capture. Phase 2 was completed in April 2000 and consisted of realigning the slough downstream of Phase 1 and installing a trash rack and diversion structure. Phase 3 was completed in December 2000 and consisted of riparian restoration through planting of native trees and shrubs to provide for cooler water temperatures and further enhance wildlife habitat. In addition, an access road to provide for maintenance, water quality sampling, and flow monitoring was constructed. A flow-measuring device was installed downstream of the ponds.

NV1_1

In 1999 the pond at Gilman Avenue crossing was unhealthy and visually unappealing.

Continued water quality improvement

Water quality monitoring sites were established upstream and downstream of the constructed wetland ponds. Preconstruction samples were collected from April through September 1999 to establish a baseline from which to measure the effectiveness of the project. Postconstruction sampling began in October 1999, and it is expected to continue for at least 10 years.

Current preliminary data suggest improved water quality and reductions in the levels of fecal coliform bacteria, phosphorus, ammonia, and heavy metals. Other immediate results of the project have been an increase in wildlife such as muskrat and deer in the area and a variety of birds, including herons, geese, ducks, blackbirds, and swallows. As indicated in the photo of the completed project, the results are aesthetically pleasing. Future phases will occur in the town of Minden and include plans for public parks, bike trails, bank stabilization, riparian restoration, and wildlife habitat enhancement.

Funding to date for Phases 1 and 2 includes $45,000 of section 319(h) funds and $86,745 in local matching funds.

NV1_2

The restoration project improved water quality, created wildlife habitat, and enhanced the visual appeal of the pond.

 

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Middle Carson River Restoration Project:
Bioengineering Used to Restore Unstable Banks



Contact:
Jean Stone
Nevada Division of Environmental Protection
Nonpoint Source Management Program
775-687-4670 (ext. 3090)
jstone@ndep. carson-city.nv.us
Primary Sources of Pollution:

unstable stream banks
Primary NPS Pollutants:

sediment
Project Activities:

bank stabilization through vegetative treatment and redirection of flow away from unstable banks
Results:

74 percent average cover on all vegetative treatments

35 percent regeneration of willow clumps



In 1995 a group of ranchers and other concerned local citizens living along the Middle Carson River near Dayton, Nevada, formed the Middle Carson River Coordinated Resource Management Planning Committee to find ways to manage and restore the river. The effort was spearheaded by the Dayton Valley Conservation District (DVCD), with the support and cooperation of numerous community groups and agencies, including the Carson Water Subconservancy District, Western Nevada Resource Conservation and Development, Natural Resources Conservation Service, and Lyon County. In 1996 the DVCD hired Kevin Piper as watershed coordinator.

The strength of the Middle Carson group is their ability to work together to implement "on-the-ground" projects. Under Piper's leadership, several bank stabilization projects have been completed, and the group supports education and outreach programs in coordination with local schools.

Restoring streambanks with bioengineering

Bioengineering, which uses vegetative techniques in addition to "hard" structures such as riprap, is the cornerstone of the bank restoration projects. Work began on the Glancy property near Dayton in 1998, with the construction of five stream barbs to redirect flow away from the unstable banks. The quiescent areas behind the structures collect sediment and allow natural regeneration of native vegetation. Several vegetative treatments, including brush mattress layering, brush trenches, juniper revetments, willow clump planting, and seeding, were used to provide bank stability, reduce erosion, trap sediment, provide shading, encourage natural plant growth, and restore wildlife habitat.

Monitoring to document improvements

A long-term monitoring program is being implemented to evaluate the effectiveness of the best management practices. Activities include aerial photography; annual survey of channel cross sections to determine the degree of accretion/degradation; monitoring of vegetation growth to assess changes in habitat; analysis of soil characteristics to document particle size, erodibility, and sediment transport potential; and hydraulic modeling to determine water surface elevations at specific recurrence intervals.

Monitoring conducted 9 months after project completion showed an average of 74 percent cover on all vegetative treatments, with about 35 percent regeneration of the willow clumps. A topographical survey indicated deposition of about 430 cubic yards of sediment between the stream barbs. Although sediment buried the lower half of many of the vegetative treatments, it provided a medium for natural cottonwood seeding. Channel cross sections showed that the low-flow channel has moved away from the bendway, suggesting the stream barbs are functioning as designed to deflect higher stream flow away from the bank.

As part of the public education component, bimonthly water quality monitoring of the Middle Carson River is conducted with the help of the River Wranglers. This volunteer group, coordinated by Lyon County teacher Linda Conlin, works with local schools to educate students about river and lake ecology. Students measure dissolved oxygen, pH, and turbidity in the field. Macroinvertebrate samples are collected and transported back to school, where students identify the number of mayflies, caddisflies, stoneflies, worms, and other aquatic organisms.

In July 2000 Kevin Piper and the Middle Carson River Coordinated Resource Management Group received the Wendell McCurry Excellence in Water Quality Award. The Nevada Division of Environmental Protection established this award to recognize individuals, firms, organizations, and governmental entities that have made significant contributions to improving the quality of Nevada's water resources.

Funding to date includes approximately $30,000 of section 319(h) funds and $30,000 in local matching funds.

 

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