Radium poisoning is a small but significant problem in portions of northern Anne Arundel County where residents pump their water from wells. In the past month, a handful of residents have tapped a little-known state law that entitles them to partial government compensation for fixing the problem.

The law, passed in 2003, covers up to one-quarter of the cost of water-treatment systems for wells with excessive radium levels. It is valid across the state but most relevant in Anne Arundel, where perhaps 5,900 of 16,000 privately maintained wells could require treatment to render them safe.

Until this summer, no one had applied for assistance. Del. John R. Leopold, a Severna Park Republican who was the chief sponsor of the bill, suspects that homeowners simply didn't know about it. So in late July, Leopold and the state housing secretary co-wrote a letter and sent it to 583 homes in areas with potential radium poisoning, informing residents about the aid.

About 30 residents have responded to the letter, said Leopold, and three homeowners have applied for financial assistance.

Holly Cheicis is seeking reimbursement for some of the $2,223 she paid last month to install a water-conditioning system at her new home in Pasadena. She moved into the house in April, knew of the radium concern and had the well water tested. When the test showed a high level of radium, she had the treatment system installed.

"I have two kids. I want the water to be good," said Cheicis, who is awaiting a response to her application for aid.

Leopold said he wants to know "if there's anybody out there who, based on passage of this bill, went out and got their well tested." He hopes more homeowners will apply for compensation, which is available to those whose household income is below $80,000, with the most aid going to those with the least income. The first 50 homeowners who apply can have their wells tested at the government's expense, Leopold said.

Radium is a radioactive element present in trace amounts in rocks, soil and groundwater. Long-term exposure to excessive levels can cause cancer. In a 1998 study, the county sampled 50 private wells and found that 15 had radiation levels exceeding federal drinking-water standards.