Linda Mumma contributed to this report.

SAN JOAQUIN COUNTY (CBS13) – Despite the state spending more money this year to eliminate nutria, the problem seems to be getting worse in San Joaquin County.

Several farms and residences sit along a series of levees in Walthall Slough, near Manteca, where nutria sightings are on the increase. Nutria are an large, herbivorous, semi-aquatic rodents. They are agricultural pests that destroy wetlands critical to native wildlife and threaten water delivery and flood control infrastructure through destructive burrowing.

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File photo of coypu, nutria or river rat. (Photo by DeAgostini/Getty Images)

Sixty-nine of the last 70 nutria found in San Joaquin County were found in the Walthall Slough area, according to newly released information from the California Department of Fish and Wildlife.

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By the end of March, 2019, more than 400 nutria were captured in an effort to eradicate the invasive South American rodent from California.

Nutria were imported in the early 1900s for the fur trade, but the market collapsed and the rodents escaped or were released. Small populations were eradicated in the 1970s, but nutria were again discovered in 2017.

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(© Copyright 2019 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)