I am looking for a ground cover for a fairly steep slope. I live in in E. Oregon the other side of Baker City. I have water available but I'm concerned about washing it away due to the slope. It's bare ground now due to new construction but it is major thistle and puncture weed country.
Thanks for your question about ground cover. First, just to give you some ideas about low water/low maintenance plants, you might want to look at those on pages 24 through 26 of this guide for Central and Eastern Oregon gardens. Those native plants that are perennial and have strong root systems are preferable. Although mentioned on other pages of this guide, Kinnickinnick (p. 14) and the ornamental grasses (pp. 22 and 23) are types of plants that have substantial root systems that secure the slope, and have no need for supplemental water once established.
Second, you might want to consider the lowly sword fern, which is very hardy and great for slope erosion control, as explained in this OSU Extension article. Although not a ground cover, its root system is great for slowing down the floods.
Finally, you might also have to do some 'hardscaping' and this publication from the USDA has some ideas for slowing down the runoff, especially before your new plants have a chance to secure the soil with their roots.
I hope these resources are helpful for you. If you still need help, you might consult the Baker County Extension Office (2600 East St., Baker City; 541-523-6418.) Good luck!