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TIMELINE-Entergy transition to MISO caps years of wrangling

HOUSTON, Dec 10 (Reuters) - New Orleans-based Entergy Corp is scheduled to turn over day-to-day control of its 15,000-mile (24,000-km), four-state transmission network later this month when it joins the Midcontinent Independent System Operator (MISO).

The move, after more than a decade of delays and wrangling, will lead to independent control of the high-voltage grid used by utilities and power generators across Louisiana, Arkansas, southeast Texas and western Mississippi.

Here is a timeline of Entergy's long road to joining the MISO, a regional transmission organization (RTO), created to fulfill the Federal Energy Regulatory Commission's (FERC) 1996 orders to encourage competition between power generators by requiring open access to transmission:

1996-99: Federal Energy Regulatory Commission (FERC) issues orders to promote competition in electric generation by ensuring fair access to transmission and outlining requirements for regional transmission organizations (RTOs). Utility membership is voluntary.

1997: Entergy utilities withdraw from the Southwest Power Pool (SPP) after SPP moves to become an RTO for the eight-state area that includes Entergy's service territory.

Late 1990s: Regulators reject Entergy's first proposal a for-profit, independent "transco" consisting of its four-state system.

2000-01: Federal regulators reject Entergy plan to join its transco into an RTO with the Southwest Power Pool.

2001: FERC approves MISO as the first regional transmission organization.

2001-03: Entergy drops two proposals to join RTOs being formed by Southern Co and other utilities: Grid South and SeTrans. Both failed to garner state and federal regulatory approval over governance issues.

2006: FERC orders Entergy to put its grid under partial third-party oversight. The Independent Coordinator of Transmission, or ICT, did little to satisfy power plant and regulator complaints.

June 2009: A public meeting brought together regulators from all four Entergy states and FERC in Charleston, South Carolina, to listen to grievances against the ICT entity. State regulators, with FERC backing, began working together formally to force changes at Entergy.

2009: Entergy's plan to move its Texas utility unit under oversight of the Electric Reliability Council of Texas (ERCOT) fails to find favor with state regulators due to high cost.

2009: Prodded by the Arkansas Public Service Commission and the committee of Entergy's state regulators, Entergy begins to study the benefits of joining the Southwest Power Pool (SPP).

2010: Entergy discloses that the U.S. Justice Department has launched a civil investigation into its competitive businesses, including operation of its transmission system.

April 2011: Entergy utilities propose joining the MISO, citing its superior benefits over SPP membership.

December 2011: Entergy and ITC Holdings announce an agreement under which Entergy would divest its transmission operation and then merge the business into an ITC subsidiary called ITC Midsouth LLC.

November 2012: In a release, DOJ says Entergy must join an RTO and divest its transmission system to resolve the antitrust division's concerns "by eliminating Entergy's ability to maintain barriers to wholesale power markets, ensuring that all Entergy service area generation is dispatched independently and at lowest cost, increasing market transparency and oversight, and properly aligning incentives for the construction of transmission."

November 2012: Entergy obtains final approval from utility regulators in Mississippi and the City of New Orleans to join MISO.

March 2013: Entergy agrees to pay $975,000 to settle a FERC claim that it violated 15 reliability standards related to its transmission system.

December 2013: Entergy is set to integrate its grid operations into MISO.