Gregg, 56, announced his decision in a February 5 letter to the diocese. The House of Bishops must consent to his resignation and Gregg said in his letter that he expects the request for consent to be made during the bishops' meeting in March.
He will resign his Eastern Oregon seat on April 30 and begin his work assisting North Carolina bishop Michael Curry the next day, the letter said. Gregg will stop working at the diocesan offices on April 15.
"This has been neither an easy nor a lightly made decision," Gregg wrote.
He said it followed a period of discernment that included an appreciative-inquiry process with the diocese that concluded during diocesan convention in the fall of 2006.
"It has been a time for me to both realize and begin to understand the exact nature of this episcopate and to address my own internal work, including both capacities and limitations," he wrote.
Gregg said he had come to realize that his was "an interim episcopate and about transition."
Gregg's predecessor, Rustin Kimsey, was bishop of Eastern Oregon from 1980-2000.
"Interims and transitions come to an end when a person or a group walks through the threshold into the next new chapter of life and work," Gregg wrote. "I believe we have reached that point."
The bishop wrote that the diocesan Standing Committee, Council and Convention, along with its consultants now have work to do. "I have no doubt that you will create a new, generative, and vital model of diocese that will form the basis for developing a model of episcopacy into which you can call your next bishop," he wrote, predicting that the work and the model will be "wonderfully fruitful for you and for the Episcopal Church."
Gregg has been bishop in Eastern Oregon since September 23, 2000 when he was consecrated as the diocese's sixth bishop. More information about Gregg's life and ministry is available here.
The Diocese of Eastern Oregon comprises about 3,100 Episcopalians worshipping in 23 congregations.