The Curious Case of Lake Mead

25 06 2015

Another post from Mark Cochrane…..

For the drought in the western US, Lake Mead is a bellwether of the situation since it is a major water source for several states and it shows such a convenient bathtub ring around its edge as the water level drops. The lake is currently more than 140 feet lower than it would be at full capacity, holding 37.1% of what it would at ‘Full Pool’.

In recent weeks the lake level has been dropping by an average of 0.08 ft/day (e.g. 1 inch/day) but for the last week it treated the lake level of 1075 (elevation) like a resistance level on a stock chart by suddenly slowing to an average drop rate of 0.01 ft/day (1/8 inch). Last night it reverted to the mean though and dropped an inch to land its level at 1074.99. It also broke through the bottom of this dynamically updated chart of the last three years of lake levels, forcing it to add a new low of 1070 (yesterday the chart ended at 1075). Who imagined it would get this bad…

The 1075 level is more than just a psychological barrier, it is one where rationing kicks in. It doesn’t start today but in a somewhat arcane manner, if the projections for the lake’s January 1st levels are below 1075 as of mid August.

What happens? Arizona takes the main hit, losing 320,000 acre-feet (AF) of water for its agricultural lands and Nevada is ‘curtailed’ by another 13,000 AF. California has senior water rights and doesn’t face ‘curtailment’ of water for its agricultural lands but the rationing will hit metropolitan areas. Since 2007, there has been a program whereby these areas could sock away water in Lake Mead using Intentionally Created Surplus (ICS) accounts. Basically by conserving water and drawing less than their maximum allowed water rights they got a credit that they could draw on at a later date. However, once the 1075 level is breached those accounts are frozen. A water-bank holiday. Not being completely clueless, metropolitan areas that saw the 1075 level looming have been making a run on their ICS accounts in the last year or more. Ultimately though, the end of ICS availability will mean that the cities will have to use less water, which likely means higher prices, quotas or similar tools to ratchet down water use further. It is possible that the lake will drop below 1060 ft this year, and highly likely this will occur next year. When this happens the last access points on Lake Mead will become inoperable – translation, no boating/tourism. In addition, power costs for energy created at the Hoover Dam will go up substantially. At 1075 feet hydropower costs will roughly double, they triple at 1050 ft, quadruple at 1025 ft, and keep rising right up until power generation ceases at around 1015 feet. Note, Hoover customers are bound by contract to have to purchase Hoover power until 2067 (link). The price of air conditioning is going up.

Just over a month ago it looked like 2016 was going to definitely be a year of reckoning for all states in the US and Mexico that rely on the Colorado River for water but ‘miracle May’ could potentially forestall things by another year. The massive flooding from unprecedented soaking rains that occurred along the upper river basin are now partially replenishing Lake Powell which sits up river of Lake Mead. Lake Powell has filled by over 20 ft in the last 6 weeks and is now filling by over half a foot a day. This has only raised it to 52.5% of capacity but it could be enough to ensure that Lake Mead can be managed to be above 1075 ft come Jan 1, 2016. Extend and pretend of the water supply can probably be finagled for another year but barring a new ‘miracle’ the pain of less water and higher energy costs for the region are likely coming in the next few years. The one hope for a temporary stay of execution in the region is if the current El Nino conditions get very strong, since those conditions are often associated with wet conditions in the drought affected areas. Of course, if that happens, there will be a lot of other problems around the world where El Nino isn’t as kind. Even if this drought abates for a while, chances are that we will witness growing tensions over water use and access in the coming decades as this is the reality of the new climates that we are forcing on the planet.