The Valley Island is cleaning up today after being slammed Tuesday night by a persistent rain storm that flooded highways, caused landslides, and forced some evacuations.

The National Weather Service reported that the highest amount of rainfall — 5.47 inches — was reported by automated rain gauges during a six-hour period at Puu Kukui in Upcountry Maui, followed by 4.82 inches at Hana Airport. Waikapu Country Club in Wailuku reported 2.17 inches, followed by 2.12 inches in West Wailuaiki in Keanae.

Maui remains under a flash flood watch through Thursday afternoon, the National Weather Service said today. A flash flood watch means that conditions may develop that lead to flooding.

Tuesday night, county officials said police and fire crews evacuated 11 residents out of Iao Valley tonight due to flooding. More residents may have self-evacuated from Happy Valley, officials said.

Heavy rain and overflowing streams shut down Hana Highway and Honoapiilani Highway in several areas due to landslide.

Maui County activated the Civil Defense Emergency Operations Center and opened three emergency shelters: the Lahaina Civic Center, War Memorial Gymnasium and Hana High School, with 15 people sleeping overnight at Hana High and eight people staying overnight at War Memorial Gymnasium. There were no overnight stays at the Lahaina Civic Center shelter. All shelters were closed this morning.

Maui Red Cross volunteers worked at the shelter and are canvassing the hardest hit areas today to assess damage, officials said.

This morning, Maui’s Department of Water Supply recommended customers in the Central and South Maui areas boil water before consumption due to possible contamination from flooding. Affected areas include Kahului, Wailuku, Paia, Spreckelsville, Puunene, Kihei, Wailea, Makena and Maalaea.

The advisory is a precautionary measure since there are no water quality violations, county officials said. Maui residents were advised to boil water three minutes prior to consumption or use, or use bottled water.

Maui county water supply personnel are flushing water lines to ensure clean water. Laboratory personnel will take samples today to verify water quality, officials said.

The county also asked residents and businesses in the Lahaina, Wailuku and Kahului areas to conserve water and to avoid any unnecessary water use until further notice. Heavy rain forced the closure of the Lahaina Water Treatment Plant, officials reported.

The state’s Clean Water Branch issued a brown water advisory for the island, advising the public “to stay out of flood waters and storm water runoff due to possible overflowing cesspools, sewer manholes, pesticides, animal fecal matter, dead animals, pathogens, chemicals, and associated flood debris.”

The Maui Department of Parks and Recreation closed Papalaua Wayside Park, Baldwin Beach Park and Kepaniwai Park in Iao Valley due to bad weather and safety concerns. Heavy flow from Iao Stream partially collapsed part of the parking lot at the park. Mudslides also covered the area with debris.

The state closed Iao State Park and Mala Ramp in Lahaina due to debris from Kahoma Stream runoff.