Saturday, March 19, 2016

The problem with ditches

About 3 weeks ago ("Taro isn't Maui's future, either," February 27), I explained why restoring the streams of East Maui and Na Wai Eha will not produce much increase in taro production. The other end of that problem is the ditches.

Who will maintain them, and why?

Recently the debate over extending the leases of East Maui Irrigation has heated up in the Legislature. Whatever happens, EMI owns at least the parts of the ditches on its own land. If it loses the leases, what reason would it have to continue to maintain the ditches in the watershed which are on public land?

I suppose whoever obtains the water leases could contract EMI to look after the ditches. It is the only entity with knowledge to do so.

Where the money would come from is a puzzle. This puzzle will require solving soonest with Wailuku Water Delivery, which does own most of its ditches but has no income except delivering water.

It has 2 big customers, King Kamehameha Golf Courses and HC&S. HC&S will soon drop out.

In East Maui, the puzzle may lie unsolved for years but will someday have to be handled.

Money will be the least of the problems.

EMI can harvest 200 million gallons a day when it’s wet. (The total flow in a storm is 10 to 100 times bigger. This week I saw a taro farmer claim that a mixture of fresh with ocean water is necessary to the health of the nearshore ecosystem. Restoring stream flow will have very little effect on overall flow of freshwater into the ocean, although by raising the minimum amounts it might perhaps have some discernible effects on the limu.)

In the dry season, EMI gets as little as 7 to 8 mgd (back in the ‘70s), although since I have been on Maui the minimums have stayed above 12 mgd.

By contract, the Department of Water Supply can take 12 mgd, although (and Mayor Arakawa should be made to explain this), it physically can accept only about 8 mgd – 7 mgd for Makawao-Pukalani-Kula and 1 mgd for the Kula Ag Park.

After new farming ventures in the valley fail – as they all will – the total demand from EMI ditches will fall to some quite small figure. I don’t know exactly what, but let’s say 25 mgd.

Nobody is going to maintain a 200-mgd capacity system (that averages about 160 mgd) to supply a maximum of 25 mgd. The system will shrink to fit.

This will happen whether or not the water commission imposes returns to the streams. Which it will, eventually.

Let’s say the 200-mgd system shrinks to 50-mgd. In a drought, the minimum will no longer be 12 mgd. It will be less – maybe less than 7 mgd.

Then people at the farther ends of the mid-level system will turn their faucets and nothing will come out.

In the ‘70s, the county put tankers at spots in Kula and people could draw water, like in Flint today. The county no longer has tankers, and the population is much bigger.

So that won’t work again.

The same problem should not arise in Na Wai Eha since the water department is taking all the surface water it can get. The former Brewer ditches will not feel any pressure to contract through lack of demand.

The threat there is lack of management of the watershed, owned by Wailuku Water, which does not have the resources to protect it. If miconia gets loose there, then Maui is in trouble.

The watershed is for sale and should be in public hands. Arakawa outsmarted himself by trying to buy just the intakes and got nothing.

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