Credit unions should contact their state or federal regulator if market conditions cause “unusually large deposit inflows or draws on existing lines of credit,” NCUA Chairman Debbie Matz wrote credit unions Wednesday.

She wrote that the combination of the decision by Standard & Poor's to downgrade the United States' long-term debt rating and market volatility could cause strains on the credit union system though she noted that credit unions have “ample capacity to meet members' financial needs.”

Matz said that even after the Standard & Poor's downgrade the agency's examiners have assigned zero risk weights to credit unions' investments in Treasury Securities and NCUA Guaranteed Notes.

The agency's guaranteed notes were among the securities that S&P downgraded. However, they have all been collateralized and sold.

She also noted that the S&P downgrade only covers four unsecured debt issues from two corporate credit unions that the agency guaranteed under its Temporary Corporate Credit Union Liquidity Guarantee Program.