Jim Costa looks as though he’s about to lose his previously-safe Democratic seat in the House because of the fish that devoured the Central Valley.  The feds turned off the irrigation spigot in one of the nation’s most productive agricultural areas to protect the Delta smelt, creating a modern Dust Bowl and destroying the livelihood of tens of thousands of Californians in the process.  Now Costa, defending a D+5 district that has been Democratic since the 1992 election, finds himself ten points down to his Republican challenger in the latest Survey USA poll:

In an election for US Representative from California’s 20th Congressional District today, 10/25/10, Republican challenger Andy Vidak is atop incumbent Democrat Jim Costa, 52% to 42%, according to SurveyUSA polling conducted in English and in Spanish for KFSN-TV Fresno.

Costa has experienced across-the-board erosion since SurveyUSA’s last poll 6 weeks ago: Among women, Costa had led by 14, now leads by 2. Among votersage 50+, Costa had led by 3, now trails by 14. Among voters without a college degree, Cost had led by 6, now trails by 11.

Whites vote Republican. Hispanics vote Democrat. If Hispanic turnout is higher than the 36% shown here, Costa performs better, but still trails. For example, if Hispanic turnout is modeled at 40%, Vidak today would lead by 7 points. If Hispanic turnout is modeled at 30%, Vidak would lead by 12 points.

Costa did attempt to head off the decision to cut water supplied to the Central Valley in 2007, sending a letter to the US Bureau of Reclamation for some kind of mitigation to the judicial decision to turn off the pumps.  However, Costa apparently hasn’t done much else — and more to the point, neither has the Democratic majorities in the House and Senate.  No significant action has been taken to restore the needed irrigation for Central Valley farmers and the American agricultural industry that relied on those lands for jobs and economic prosperity.

Under those circumstances, it’s hardly surprising that Costa will pay the price for inaction.  Vidak wins independents in the district by a wide margin, 57/32, and manages to win 20% of Democrats, too.  While he trails among the Hispanics that comprise 63% of the population in the district, he doesn’t trail all that badly for a Republican candidate (36/57), certainly not by the wide margins Democrats have enjoyed over the last several cycles.  Most problematic for Costa, Vidak leads by five among those who have already voted — and by fourteen among those who haven’t.