Fatal car crashes on Hawaii island have increased 20 percent this year over the same period last year.

There have been 12 fatal crashes resulting in 13 fatalities this year, the Hawaii County Police Department said Tuesday.

That compares with 10 fatal crashes — two of which involved multiple deaths — resulting in 13 fatalities during the same period last year.

In the week ending Sunday, Hawaii County police arrested 15 motorists on suspicion of driving under the influence of an intoxicant. Four were involved in crashes. Two were under age 21.

This year, there have been 620 DUI arrests, compared with 589 during the same period last year, an increase of 5.3 percent.

Also, there have been 826 major accidents so far this year, compared with 890 during the same period last year, a decrease of 7.2 percent.

Waterfall work will improve native habitat

Work on the Waihee Ditch waterfall on Maui will improve the habitat and migratory routes of native stream animals, including oopu (gobies), opae (shrimp) and hihiwai (snails), the state said Wednesday.

While those animals can climb wet rocks, an overhanging concrete lip at the top of the waterfall limits their movements. On Monday, workers will begin to replace the overhang with grouted rocks from the stream.

The Commission on Water Resource Management also asked Wailuku Water Co. to reduce the amount of water going into the Wailuku River. The project is expected to wrap up in about two weeks.