A problem in Boulder, which my geology 2 professor pointed out two semesters ago is the geographical location of the City of Boulder and it's propensity for flooding I read a great article on the topic, a little long but worth it if you are interested http://www.getboulder.com/visitors/articles_w05/flood-ready.html...
here is a little taste of one authors description of what the flood will look like if it happened today...
"a wall of water rages down Boulder Canyon, hurtling trees, cars and boulders the size of Volkswagens. Hitting the mouth of the canyon, the racing wall is carrying 30,000 cubic feet of water per second (cfs). Buildings are destroyed, bridges collapse and people are washed away, while those on high ground can do nothing but watch."
The last flood happened in the year 1894. It killed 144 people and cost 35.5 million dollars in damages. This happened at the bottom of local Thompson Canyon. However the real issue would be if the flood came out of the Boulder Canyon mouth instead. There is far more development, the Boulder Public Library, city buildings, Boulder High School, CU housing etc... an it is estimated that coming out of Boulder canyon, the destructive force would be around three times as powerful as the one that came out of Thompson, given the exact same variables.
The typical flow of the water coming out of the canyon is 10 cfs in December, in peak seasons it could run as high as 700 cfs. If the 100 year flood repeated, we would see a flow around 12,000 cfs. The scariest thing is that the 100 year flood is not even the biggest issue, it was just way to look at a perhaps near future problem. There is also a 500 year flood that is estimated to be far more destructive and there are over 5,000 private Boulderite properties within this zone.
So what should be done here? Better infrastructure, move housing and construction lines? Build a dam somewhere or create levee walls?