Pittman Wash Pilot Wetlands

This ½-acre pilot project is designed to determine whether constructed wetlands can improve the water quality of urban runoff, which currently represents approximately 10% of the flows in the Wash.  The project will also evaluate the feasibility of operating constructed wetlands in an urban flood control channel, identify challenges and constraints associated with this type of setting and optimize design and construction techniques.  If the project is successful, a full-scale tributary treatment wetland may be constructed.  The United States Bureau of Reclamation (Bureau), City of Henderson, Clark County Regional Flood Control District, Las Vegas Wash Project Coordination Team, and Southern Nevada Water Authority partnered to initiate the study, which is funded by a Bureau grant. 

The project site is located adjacent to the Arroyo Grande Sports Complex in Henderson, Nevada and is divided into two cells, a subsurface flow cell and a surface flow cell, to determine which of these two wetland technologies offers the most significant water quality benefits.  The subsurface flow cell consists of ¾ -inch gravel to a depth of approximately two feet and will be planted with bulrush.  The surface flow cell consists of open water areas interspersed with shallow beds that will also be planted with bulrush.  Each of the cells is lined with clay to prevent infiltration by shallow groundwater.  A diversion channel supplies flows from Pittman Wash to the two cells.  Water quality will be sampled at various sites within each cell once the bulrush has matured. 

Pittman Wash Pilot Wetlands

Site construction for the Pittman Wash Pilot Wetlands was completed in April 2005.  California bulrush (Schoenoplectus californicus), hardstem bulrush (S. acutus), Olney’s bulrush (S. americanus) and alkali bulrush (S. maritimus), were identified as suitable for the project site and were planted in the cells in May and June of 2005.   A series of storms and flood events filled the site with sediment in July, August and October.  Consequently, the height of the concrete walls surrounding the vulnerable sides of the site was raised in an effort to protect it from damage related to high-velocity floodwaters.  Planting activities are scheduled for May of 2006 to allow adequate growth of the vegetation so that water quality monitoring can begin by late summer.