Hi Michael, we're so sorry we weren't able to respond to your question in a timelier fashion! You didn't mention the exact composition of your sourdough starter, however with its thirstier whole grain elements and your dry environment, you may find that increasing the hydration of the starter a bit will help with rising; you may find that increasing the hydration by just 10% makes a difference. If you're concerned about the chlorine in your water, try allowing a pitcher of water to remain open on the counter overnight, which will help dissipate some of the chemicals. When it comes to making sourdough bread, increasing the hydration of the dough a bit may also be necessary. Also, you may find that allowing the shaped rise to occur overnight in the refrigerator makes the final proof a bit easier and less stressful. For more tips on high-altitude sourdough baking, check out Maurizio Leo's article on this subject. He lives at high altitude and bakes beautiful sourdough breads, so he's an expert!

• Reply