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Water Planning in the Climate Change Era

Juliet Christian-Smith, a climate scientist with the Union of Concerned Scientists, talked to Water Deeply about the two things we need to ensure a reliable water supply in the future. And she explained why the best climate science should guide our water resources planning.

Written by Tara Lohan Published on Read time Approx. 6 minutes

California’s Water Commission is in the process of creating regulations for how to spend $2.7 billion that taxpayers approved to fund new surface and groundwater storage projects. This was part of Proposition 1, a water bond, passed in 2014.

It’s a chance to set the stage for a new era of water management and infrastructure in California and Dr. Juliet Christian-Smith wants to be sure the state is using the best climate science when considering the criteria for which projects to green-light.

It makes sense. If you’re planning to build a project that lasts a century you should be using climate modeling that considers what the world will look like in a hundred years. Except so far, that’s easier said than done. But Christian-Smith hopes that is about to change, because this year is looking like it will be a crucial year in deciding the future of California’s water.

Christian-Smith talked to Water Deeply this week about why 2016 is a tipping point for water in California and how the drought has tested the limits of our 20th-century water management system.

Water Deeply: What should Californians be most concerned about when it comes to the impacts that climate change will have on our water resources?

Juliet Christian-Smith: The top issue that really should be changing the way we manage the water system is the shift away from snowpack – the impacts to our snowmelt-fed reservoirs, rivers and streams. Historically, that has been supplying a third of our water supply and we know that there is consensus across all climate models that the warming temperatures mean that we are getting more precipitation as rain rather than snow. And that the snow we have is melting sooner. That means water is not available when we need it the most, in the hotter months. So the water availability is out of phase with water demand.

A lot of times the way people define drought is a lack of precipitation but I think a more holistic definition of drought is when supply isn’t able to meet demand. There are a lot of ways our demand is outstripping supply already but climate change is exacerbating that.

Water Deeply: Considering the climate models, how should water managers and state officials be planning 50 years or longer down the road?

Juliet Christian-Smith: When we think about 50 years into the future, which we are doing right now as we are on the precipice of giving out the Proposition 1 water bond funds, it would be for infrastructure that would last a century or more.

That kind of infrastructure would be around through a period that looks very different from historical averages. We can’t use historical data or hydrology to design the systems. Trying to incorporate climate science and climate projections into designing the water system of the future is still a very novel concept. It presents a challenge to policy-makers and decision-makers because it hasn’t been done very often.

Water Deeply: Has it not been done much because we’re not used to considering climate models in this type of planning or because those doing the planning are not confident in the climate models?

Juliet Christian-Smith: The issue of uncertainty comes up a lot when we’re talking about climate change. And yet when you look at any kind of decision you’d be making about how to use land, what crops to plant, how you think about water rights changes and legal disputes – every decision we make in the water sphere – there is great uncertainty.

Will the infrastructure of the state be the same 100 years from now? Will we have delta tunnels? Will we be protecting the same endangered species? Will we be protecting new species? Will we have the same amount of irrigated agriculture? Will we have larger cities and where will they be? The uncertainty abounds and many times planners will be very nervous about uncertainty about climate change projections and not really consider the uncertainties that exist in all these other dimensions.

When we look at the climate change projections, there is actually a lot of certainty around changes to snowpack, there is a lot of certainty around the changes for temperature.

Water Deeply: How can we ensure that the best science is being used when we are considering large infrastructure like potentially building new dams or conveyance systems?

Juliet Christian-Smith: We have to first include climate change as a factor that we are analyzing in our policies. Then the next step is to create some common metrics and a common approach to quantifying and evaluating climate resiliency. How we assess how resilient a particular project is to climate change is an emerging area of policy.

What we are really looking for is the use of the best available science and that the science used matches the project lifetime. If the project is going to have a lifetime until 2110, then that analysis of the climate impacts should match that same timeline.

Water Deeply: You’ve written that 2016 is a tipping point for water in California. Can you explain why?

Juliet Christian-Smith: We think 2016 is a year when a lot of big changes are going to begin.

This year for the first time ever, well logs became public. Gov. Brown and the legislature allowed these records of where groundwater wells are drilled and how deep they are drilled to become accessible to the public. This is an extremely useful amount of information in terms of just understanding half of the water cycle – where we are pulling from, how deep our aquifers go, which wells might be jeopardized by lowering groundwater tables, the direction that groundwater is flowing between basins.

Politically there is a series of important decisions being made about the Sustainable Groundwater Management Act in terms of how we actually take the act and translate it into meaningful on-the-ground action. The regulations that set the bar for what sustainability means in practice are coming out later this month.

Then there are the $2.7 billion in water bond funds – they are writing the criteria about how that funding will be distributed to create the water system of the future.

And the state Water Board announced how it’s going to implement Senate Bill 88, the new requirement that all surface water users report the water they are diverting or using. We had a very unclear picture of how the water that fell in the state of California was being distributed and we didn’t have a very clear understanding of who was taking surface water.

We are entering an era, I think, of better information and we are also faced with some really important decisions around what we want the future to look like.

Water Deeply: It looks like this year is shaping up to be a wet one. How can we keep people focused on the big picture of climate change and its long-term impacts?

Juliet Christian-Smith: I think people were struck by that image from 2015 of that completely dry meadow where we typically do the snow surveys and I think it was a wake-up call that we really are testing the limits of our 20th-century water management system.

This wet year is not going to refill all surface water reservoirs and there is no way it could ever refill the groundwater aquifers that we have not just tapped out but we have drawn down into negative territory for decades. It’s a shame in many ways that people can’t see the empty reservoirs that are underneath our feet because they tell a story about a long-term drought. The groundwater tells us a story of a system that is in a structural deficit.

The story is kind of just beginning in terms of how we start to deal with a changing system. There are a lot of really good ideas on how to start capturing and using the water that we have – stormwater, recycled water, floodwater, wastewater – in a better way. It really will require a lot of effort and a lot of public attention. Those are the hardest things, the public attention and the political will. If we can continue to elicit those things we have a chance of having a reliable water supply in the future.

Top image: In this aerial photo taken Tuesday, April 28, 2015, a spillway sits more than a 100 yards (90m) away from the water level of Lake McClure in Mariposa County northeast of Merced, California. (Rich Pedroncelli, Associated Press)

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