A Central Valley farmworker died Friday afternoon while working on an irrigation system in Richgrove, prompting the United Farm Workers union to call Monday for stricter enforcement of heat-illness prevention laws.

The 37-year-old man was checking irrigation equipment in a field owned by Visalia-based Etchegaray Farms four miles east of Highway 65 when he collapsed, according to a company report cited Monday by Cal-OSHA. It said the man was unresponsive when emergency medical workers found him at 3 p.m.

Cal-OSHA said it is investigating the case.

The UFW identified the man as Juan Ochoa and said he may have been living in Delano. A Cal-OSHA spokesman said the man lived in Earlimart; it would not confirm the man's name.

A Monday news release from the UFW said the incident "appears to have been caused by neglect rather than ignorance."

Asked why the union believes the man died of preventable heat illness, UFW Vice President Giev Kashkooli responded in an email saying, "Ochoa's brother, Alejandro, reported to the media he and his brother, Juan, were working without shade and that he (Juan) had to walk approximately three miles to get help."

UFW President Arturo S. Rodriguez said in Monday's news release that the man's death "only proves that whatever the state is doing to protect these workers is obviously not working."

"With temperatures continuing to be over 100 degrees in the week to come, we need to see immediate compliance with all laws by all employers, which the state should encourage with aggressive enforcement of California's heat illness-prevention regulation."

Etchegaray Farms declined to comment Monday.

Cal-OSHA records indicate that Etchegaray has experienced two accidents, one involving a worker's death, since 2010, and that the company had to pay fines for problems including a "serious violation" of safety rules.

The agency had minimal information on the more recent accident, in 2012. The case was closed earlier this year, apparently without citations issued to the company.

In 2010, according to Cal-OSHA, a worker at an Etchegaray facility in McFarland was struck in the head by a blade from a wind machine that had begun shaking. Citations were issued but an agency spokesman was unable to provide details Monday.

In 2009, Etchegaray was cited for numerous violations, including a serious one that had to do with pulleys that were left unguarded at a facility in Earlimart.