Quagga mussels are invading AZ waterways. They are related to zebra mussels that have taken over mid-west waterways.
The US spends between $500 million to $5 billion to fight this problem. These mussels clog waterways & pipes. They filter food from the water, decreasing the food source for native fish species. By clearing the water, weeds can now grow in 20' of water where they couldn't before. Again raising costs. You will eventually be paying these costs. There is very little public funding or coordinated funding in AZ to deal with this problem. AZ Invasive Species council has no funding.
Great presentation at SW Veg Mgmt by Tom McMahon, AZ Game & Fish. Here is a photo of what the quagga mussels do to pipes. This pipe from Lake Pleasant, AZ.