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Wetlands Research

Demonstration Wetland Project - City of Henderson Water Reclamation Facility

Through a cooperative agreement between the Bureau of Reclamation, City of Henderson and Southern Nevada Water Authority, the Las Vegas Wash Coordination Committee constructed the Demonstration Wetland at the City of Henderson Water Reclamation Facility in 2001 and operated the project until mid-2009.

The primary goal of the project was to determine whether constructed wetlands could be used to improve the water quality of treated wastewater in Southern Nevada. Additional goals included offering a habitat for birds and identifying wetland plants that could thrive in spite of fluctuating water levels and extreme summer heat.

Constructed in a six-acre pond, the wetland contained three unvegetated loafing islands and 11 submerged islands planted with bulrush. This design, which left approximately 80 percent of the surface area devoted to open water, was meant to encourage water quality improvements while also providing mosquito control. Treated wastewater flows entered the pond from the west and flowed east, perpendicular to the hummocks.

Several plantings were needed to establish vegetation within the wetland. Of the 20 species of native wetland plant, only three were suited for our environmental conditions: California bulrush (S. californicus), hardstem bulrush (S. acutus), and Olney bulrush (S. americanus).

By the time vegetation filled in, scientists initiated a variety of studies within the pond to quantify the impact the wetland had on water quality. Hydrologists collected extensive water quality data, monitoring water chemistry at the inflow, outflow and select sites within the wetland. Biologists conducted bird surveys to quantify the habitat value of the wetland and determine whether bird use might negatively impact the wetland’s nutrient and bacteria removal efficiency. They also monitored vegetation, first in the fall of 2005 and then in the spring and fall of 2007 and 2008, assessing plant growth and cover and analyzing tissue samples for nutrients and contaminants of concern.

This research yielded a large amount of data over the years. Water quality monitoring detected significant changes in select nutrients and metals between the inlet and outlet. Nitrate and nitrite concentrations were significantly reduced (p<0.05). Ammonia concentrations increased at the outlet and did not have a distinct seasonal trend (p<0.05). Aluminum, chromium, copper, selenium and zinc concentrations were significantly lower (p<0.05), while manganese concentrations increased at the outlet (p<0.05). Fecal coliforms were reduced.

California bulrush accounted for approximately 55 percent of the vegetative cover on the pond, while hardstem and Olney bulrush represented about 20 and 25 percent respectively. California bulrush also had the largest mean culm (i.e. stem) height and diameter, the highest percentage of live material, and provided the largest storage of nutrients. Harvesting of bulrush from four of 11 hummocks in spring 2008 negatively impacted height and cover of the species, but it recovered to near pre-harvesting levels by the fall. In regards to plant tissue analysis, spring concentrations were significantly higher than fall for total nitrogen, total phosphorous and selenium (p<0.05).

Biologists identified more than 100 bird species using the wetland, including 15 that nest on the site. An average of more than 250 birds were found in the wetland during each survey, but birds do not appear to have negatively impacted removal efficiencies of nutrients and fecal coliforms, demonstrating that constructed wetlands can improve water quality while providing beneficial bird habitat.

To learn more about this project, read the Final Wetland Demonstration Projects Report (1.82 MB).

Visit the Demonstration Wetlands Project

The City of Henderson operates the ponds at the Water Reclamation Facility as the Henderson Bird Viewing Preserve, a park that is open to the public. If you would like to visit the demonstration wetlands, take a trip to the preserve and ask the visitor center staff for directions to pond 9 (the demonstration wetlands project pond).

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Las Vegas Wash Project Coordination Team • 100 City Parkway, Suite 700 • Las Vegas, NV 89106 • (702) 822-3300