The deadline is Monday for community input on a study being conducted to identify flood mitigation projects in Waianae.

Officials are looking into “low-cost, high-impact projects” that can be implemented by the community with the help of state and city agencies.

The U.S. Army Corps of Engineers has commissioned the $390,000 study to address flooding that occurs with rainfall of 7 inches in a 24-hour period. Identified study areas are the Mailiili Stream, including Puhawai, Lualualei Homestead and Puuhulu roads; the Maili Stream, which includes Paakea, Apana and Kaukama roads; and the Ulehawa Stream, including Hakimo, Iliili and Kuualoha roads.

Findings are expected to be published this summer, but residents are being asked to assist by submitting suggestions and feedback by Monday.

Engineers from Group 70 International, the consultant conducting the study, presented preliminary findings and suggestions at a community meeting last month with representatives from federal, state and city agencies, including the state Department of Land and Natural Resources, the Hawaii Emergency Management Agency, state Rep. Jo Jordan and state Sen. Maile Shimabukuro.

Key causes of flooding were identified as no well-defined drainage systems in agricultural areas; inadequate maintenance of private streams, ditches and culvert pipes; illegal dumping in streams and ditches; and construction and building in flood-prone areas.

Preliminary mitigation suggestions include putting in roadside ditches and swales, or channels, to collect runoff. Group 70 also plans to mail letters to property owners along the proposed project routes to inform residents and gather additional feedback.

Jordan (D, Waianae-Makaha-Makua) said community cleanups have been successful in clearing out old tires and other trash clogging drainage areas. She has also worked with agencies and volunteers to help educate residents on how to maintain and clear drainage areas on their properties.

But she said officials and the community will need to work together to come up with creative funding sources to implement the recommendations.

“Once Group 70 gets done with what they’re doing, we’re continuing on because we have a lot more work to do,” Jordan said at last month’s meeting. “What we got to do is little bites at a time. We haven’t gone away. We haven’t forgotten.”

The Lualualei drainage basin in Waianae has experienced frequent and severe flooding. The Lualualei Flood Study was completed in 2001 in response to the problems, but recommendations were not implemented due to high costs and issues with private land ownership. Additionally, $4 million of state funds were appropriated several years ago for a flood mitigation project in Lualualei Flats and the Puhawai Stream.

DLNR and the Hawaii Emergency Management Agency had asked the Army in 2012 for help in providing updated information to the 2001 study.

Public input and suggestions can be submitted to Gary Coover, a Group 70 engineer, at gcoover@group70int.com.