Hi! I'm Henry and I study fish, dams, reservoirs, and river systems. Rehabilitating aging reservoirs from a habitat viewpoint can be challenging financially and biologically. But what do we do when the dams that create these reservoirs also succumb to aging? 1/10 #HydroFish2020

Oroville Dam in California holds back the 2nd largest reservoir in the state and was on the brink of failure in 2017. This forced 180,000 people to evacuate and has cost over 1 billion USD in repairs. The dam is only 52 years old. 2/10 #HydroFish2020

There are approximately 50,000 dams over the age of 50 in the USA. Nationwide our dams have a D rating with 17% having a high hazard potential. Learning from our reservoirs, being proactive in addressing these issues is key to reaching ideal outcomes. 3/10 #HydroFish2020

Conceptually the relationship between our dams and reservoirs is inherently linked. The aging that occurs in the reservoirs and our responses operate on faster time scales than the dams. Ultimately, what happens with the dam dictates the future ecosystem 4/10 #HydroFish2020

We present a starting point on how we can proactively address aging dams and reservoirs. Our emphasis is that every action we undertake will likely be expensive and have complex tradeoffs. Unless the dam is removed we will always be managing against aging. 5/10 #HydroFish2020

We are already seeing the costs of not being proactive in our management. In the great plains alone we have encountered the full spectrum of risks associated with a reactive management mentality. 6/10 #HydroFish2020

Bonny Reservoir and Dam are a "good" reactive scenario in that action was driven for legal reasons and thus there was a low safety risk. But it was transformative from an economic and ecological point of view. Here I show how the ecosystem has transitioned. 7/10 #HydroFish2020

Red Willow Dam is a "bad" reactive scenario since emergency actions were needed and corrective measures took years to finalize and implement. Lack of clarity of future outcomes and challenges to find funding are opportunities to improve on. 8/10 #HydroFish2020

Spencer Dam is an "ugly" reactive scenario since no actions were able to save the dam and cost over 1.4 billion USD worth of damage. Such a drastic outcome has untold ecological, economic, and social costs both short and long term. We need better outcomes. 9/10 #HydroFish2020

New dams are being constructed throughout the world and will inevitably face the consequences of aging. How do we achieve ideal outcomes for aging dams and reservoirs in a proactive manner? Read the article for our take on the issue - https://link.springer.com/article/10.1007/s00027-019-0679-3 10/10 #HydroFish2020