Dependable Erection

Tuesday, March 04, 2008

Drought watch

Wow. Inflows at Little River are up to almost 500 cfs. They haven't started climbing that high yet at Lake Michie, but give that a few more hours.

There's more rain in the forecast for Friday. Bet those lake levels look a lot better come Monday.

UPDATE: Inflows at Lake Michie and Little River are above 1200 cfs and 1400 cfs respectively at 1:30 am. If they stay at those levels for even half a day, we can add close to another month to the water supply.

UPDATE II: As of 7:45, inflows at Lake Michie were nearly 3300 cfs, and appear to be peaking in the next hour or two. At the Little River, they peaked last night at around 1400 cfs, and are down to just over 1000.

Still very good news for when lake levels are updated. Showers are still considered "possible" for Friday.

UPDATE III
: Lake Michie is now essentially full. With inflows still near 3000 cfs, the question is how to save that water for the future, rather than letting it all flow downstream. I assume the pumps are working to move water from Lake Michie to the Little River reservoir, which remains 13.5 feet below capacity. It doesn't look like the Teer Quarry is being filled up right now, either, although that may simply be a function of not updating the numbers as often as the other reservoirs.

So, what does this mean?

Firstly, i think, we've got the reprieve that seemed so unlikely 10 weeks ago. There's almost 8 months of water stored up now, and more on the way. So we've got some breathing space to make considered decisions, without having to panic.

Second, the move to Stage V restrictions is now out, i think, and i expect pressure to build to step back from the current Stage IV restrictions. It's likely that if we get more rain on Friday, and successfully divert excess water from Lake Michie to Little River, we could be at around 95% of our capacity by the weekend. That will make it impossible to keep Stage IV restrictions in place. So i expect a loosening to Stage III restrictions by the end of next week.

Third, there will probably be informal requests from other jurisdictions that may not have benefited from recent rainfall for Durham to reduce its usage of Jordan lake water. This will mostly be a PR move, but it's one that shouldn't be ignored.

Fourth, usage will climb back up to near last year's levels. Current demand is running about 15% below last year. That'll probably stabilize at around 8-10% below last year, especially if we get into a growing season under Stage III, which allows for some outdoor watering under certain restrictions.

The remainder of this year and next year should give us a better understanding of whether we've entered into a pattern of changed rainfall patterns, with a wet and dry season that will require better long term storage and management of water resources, or if the past few years are merely an aberration. We certainly need to plan for the former, which means better regional cooperation and more attention to development, and hope for the latter, rather than the other way round.

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2 Comments:

  • Well, if it's any consolation, if it goes over the Lake Michie dam, it just goes to Falls Lake, where it's not going anywhere (aside from the Corps of Engineers daily allowance downstream...). That helps Raleigh, which while I admit I have a perverse reaction against, is probably a good thing in the long run.

    I guess I never had much doubt that the lakes would be close to full by the end of April, unless we really entered a bizarro weather pattern. What I'm worried about now is groundwater. Last night's rain was great for the reservoirs, but did nothing for the groundwater levels, which if dry period stream flows are any indication, are still really low. The groundwater is a much more slow-changing but also much steadier form of water storage, but it only recharges substantially during very long, slow rains, or better yet, snow, when the slow melt means that over half of it soaks in.

    Last fall, fast rains like this were a great thing, because we were down to a month of water left, and needed anything in the reservoirs we could get. But now, what we need is to recharge the groundwater for the summer. If we don't, we could be back in a bad spot come September.

    Fortunately, we're entering the time when slow rains are the norm. Here's hoping they come this year.

    By Blogger Michael Bacon, at 2:20 PM  

  • This is no time for Durham to be backing away from use of Jordan Lake. Jordan has a far larger watershed than Falls, and is apparently less susceptible to drought. In fact, the pressure to use Jordan will rise so that Durham will in turn reduce its use of the Falls Lake watershed.

    This allows the Corps to avoid the inter-basin transfer of Jordan Lake water to Raleigh.

    Of course, this would mean we (Durham) would be enabling continued runaway growth in Wake County. Sometimes, the big picture really sucks.

    By Blogger Todd, at 12:36 AM  

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