A pair of environmental groups said Thursday that they plan to sue Perdue Farms and an Eastern Shore chicken grower for alleged water pollution violations. The Assateague Coastkeeper and the Waterkeeper Alliance filed notice of their intent to seek legal action in 60 days against the Salisbury-based poultry company and the owners of a farm near Berlin that raises 80,000 birds under contract to Perdue. The groups contend that a drainage ditch feeding into the Pocomoke River, a tributary of the Chesapeake Bay, is being polluted with chicken manure washing off the farm. They released aerial photographs taken since late October showing what they said was an uncovered pile of manure and wood shavings. A pair of water-filled trenches lead from the pile to a grassy ditch nearby. The groups say water sampled from the ditch downstream of the farm in recent weeks contained high levels of bacteria associated with animal waste, nutrients and arsenic, a toxic metal. Alan and Kristin Hudson, the farm owners named in the groups' notice, did not return a telephone call seeking comment. But Perdue spokesman Luis Luna said the environmental groups' news release was "full of errors and misstatements." He said the pile in their pictures is not manure because the Hudsons told Perdue they hadn't removed any manure from their chicken houses in the past 20 weeks.