W.T.B. Financial Corp., the Spokane-based holding company for Washington Trust Bank, has reported first-quarter net income of about $17.1 million, or $6.86 per diluted share, an increase of about $5.7 million over the year-earlier quarter, but a decrease of about $3.8 million from Q4 of last year.

According to a letter to shareholders from Peter Stanton, board chairman and CEO of WTB Financial, the primary reasons for the quarter-over-quarter dip in earnings included higher operating expenses, increased provision expense due to significant loan growth, a change in allowance model assumptions, and two fewer calendar days.

Offsetting those adverse earnings impacts, according to Stanton’s letter, were continued favorable shifts in the balance sheet and improved core earning power.

“Loan growth was substantial in the first quarter, increasing $170 million to $7.1 billion, with most of that growth coming in commercial-and-industrial and construction-and-development loan categories,” the letter states.