Rocky Mountain Health Plans, a dominant and long-independent provider of health insurance coverage in western Colorado, has struck a deal to join UnitedHealthcare, the largest health insurer in the state and the country. “The value of this union is that you take United’s state-of-the-art technology and the extraordinary community relationships of Rocky,” said Steve ErkenBrack, president and CEO of Grand Junction-based Rocky Mountain Health Plans. UnitedHealthcare said it will invest an undisclosed amount in RMHP to “restore the organization’s capital base and help ensure that it becomes a stronger, more sustainable health plan over the long term.” In return, UnitedHealthcare will gain entrance to the state’s Medicaid market and access to 300,000 mostly rural customers in parts of the state where it currently lacks a reach. “We don’t have a huge presence on the Western Slope.