Summer Lake Washington Nutria Report

A reader sent us the below nutria report for the last 3 months.  The report indicates that some calls for nutria trapping have come  from Laurelhurst.

The nutria, Myocastor coypus, is a large semi-aquatic rodent. Nutria are smaller than a beaver but larger than a muskrat, however it has a round, slightly haired tail. They live primarily in wetlands, and do significant vegatative damage to marshes, damaging a plant's root system, making recovery through vegetative regeneration very slow.

Nutria can "cause extensive damage to wetlands, agricultural crops, and structural foundations such as dikes and roads.  They may also threaten human health and safety and serve as a reservoir for tularemia and other diseases.  Integrated management solutions to nutria problems may include habitat manipulation, population management, and innovative approaches and tools generated by research."

The damage is "related to burrowing and feeding. Nutria construct burrows in the banks of rivers, sloughs, and ponds, sometimes causing considerable erosion. Burrows can weaken roadbeds, stream banks, dams, and dikes, which may collapse when the soil is saturated by rain or high water. Rain action can wash out and enlarge collapsed burrows and compounds the damage."



Dear Lake Washington Nutria Group,

The following is a summary of Wildlife Services (WS) activity on the Portage Bay and Union Bay Nutria Projects on Lake Washington for the months of  May, June, and July 2011. 

WS spent 30 hours surveying and trapping Nutria, concentrating its trapping efforts on University of Washington property as well as Portage Bay shoreline and Union Bay Marsh.  WS spent a total of 8 hours surveying the Laurelhurst areas, 6 hours surveying Seattle Parks Property, 2 hours surveying Portage Bay, and 14 hours operating 8 live traps throughout the properties. 

This month WS decided to start trapping because of several sightings of nutria in the areas.  During these months we have trapped a total of 4 nutria, 2 of which have been juveniles.  We have responded to 5 calls and reports of nutria sightings this month.

The calls have been from Kirkland, Laurelhurst to the Portage Bay houseboats.

We are very anxious to find any new nutria presents or an indication of damage nutria anywhere within Lake Washington.  Nutria reporting have been decreasing in the past few months, this may be due to nutria movements to new areas that have not been previously trapped.

This month we are going to focus on building new traps that have not been tested out in these areas before. These traps are going to be floating traps that are in water 100 meters from the shore. We anticipate great success with this new trapping method because we can place these traps in these new areas. We are very thankful for all of the people that have helped us with this project.  The project total is 309 Nutria. 

WS will continue to monitor/survey all previously trapped locations and respond to calls of Nutria in the project areas.