Hi Eileen,
Thank you for your question about plants that will attract pollinators and monarch butterflies.

Following is a link to an OSU Extension publication that provides many plant options for Central Oregon. Each plant description includes photos of the plant and one or more symbols to assist you in choosing plants. These symbols include plants that attract pollinators, which are identified by a symbol of a bee or butterfly.
Water-wise Gardening in Central Oregon | OSU Extension Catalog | Oregon State University

The following publication includes information specific to monarch butterflies:
Twelve plants to entice pollinators to your garden | OSU Extension Service (oregonstate.edu)

As a note, milkweed is known to be an aggressive plant, especially when provided with additional water, so it will likely take over an area. Amy Jo Detweiler, our OSU Community Horticulturist, suggests that milkweed be planted in a container to keep it from spreading.

If you need additional information, I recommend you call the Deschutes County OSU Extension office in Redmond at<personal data hidden> and ask to speak with Amy Jo Detweiler (oregonstate.edu). Amy Jo welcomes your home garden questions and is a great resource. She may have additional ideas for you.