The Bronx Democratic Party, which helps elect Democratic candidates across the northernmost borough of New York City, has failed to disclose more than $400,000 in campaign contributions over the past four years — an apparent violation of campaign finance law.

A New York Focus review found that the state Democratic Assembly Campaign Committee, chaired by Assemblymember Jeffrey Dinowitz, transferred the funds in over a dozen installments, yet those contributions never appeared on the Bronx party’s paperwork.

It’s unclear what the Bronx Democrats used the money for. The heavily Democratic borough rarely sees competitive general elections, and the county party has not reported large expenses in recent years. Neither the Bronx party nor Assembly campaign committee, nor Bronx party chair Jamaal Bailey, responded to a request for comment.

After the Biden administration issued new lead cleanup rules Tuesday, New York is on the hook for at least $2.5 billion to replace toxic drinking water pipes — far more than the state has ever spent to remedy the long-standing health hazard.

The rules require nearly all drinking water utilities nationwide to replace lead pipes within a decade. Lead exposure in childhood and in the womb can cause severe cognitive damage, which has been linked to everything from decreased reading and math skills to increased crime and incarceration rates among adults.

But implementing the plan won’t be cheap. The Environmental Protection Agency estimates that there are still more than 9 million drinking water lines made of lead nationwide. Each line costs an average of $5,000 to replace — an estimate that predates pandemic-era inflation — bringing the total cost to at least $45 billion. Federal funds would cover only a fraction of that. President Joe Biden announced Tuesday that the federal government would release $2.6 billion to states, the latest installment of the $15 billion to replace lead pipes authorized by the 2021 bipartisan infrastructure law.