Now that the area is cleaned up, we purchased another house on the block with another neighboring lot under contract.

We are also buying more properties on the block!

(Unlike Wheat Ridge that limits them to one per owner.)No caps on the number of STRs per block/per radius, etc.

A condition of a lease that says that a landlord does not have duty to mitigate damages is void under this law."

You can see if the animal is doing any damage or making sure they are cleaning up yard waste, etc. 

I had a plumber come and assess the issue, who said that while fixing the plumbing issue might be a one day job - there was sewer water damage that I would need to worry about since it can affect the floor, sub floor, base boards, dry walls, high voltage electricity lines (because of the dryer). 

Dog outside yard, vehicle blocking, offsite dumping, dumpster diving...?

If I were you, I would let the city fix the damages when they can get to it and make temporary fixes for now. 

Some, like tings you can take out and not do major structural damage have only a 5 year life so you can write them off faster, and if you know how to do it you can take their entire cost in the first year!

Reality is that a security deposit is really just a fraction of what damage can be done, and if someone lived there for 2 decades, there is a lot of wear and tear damage I am sure.