Activity 1: Construct 8-10 vetiver and native plant sediment traps in kickouts in the middle and lower-middle areas of the Honokōwai watershed (Fig. 1).

Method 1:  Sediment trap rows will be planted along contours using a combination of vetiver slips and native species. All vetiver/native-species sediment traps installed within kickouts will be constructed to trap large volumes of sediment between rows.

Outcome 1A: An additional 30,000-40,000 lbs of sediment captured and stored annually. 

Outcome 1B: When completed, this project, along with sediment traps in 10 additional kickouts that will be constructed through a recent NOAA CRCP award, will bring the total number of kickouts addressed in the Honokōwai watershed to ~50. This represents over 60 percent of all kickouts needing attention in the whole watershed (50 out of approximately 80 kickouts total). 

Activity 2: Monitor 4-6 representative kickouts for sediment deposition within the sediment traps.

Method 2: Retention of sediment is the primary goal of each sediment trap installed. To monitor the effectiveness and to analyze in-situ efficiency, sediment posts will be installed in sediment traps within 4-6 kickouts constructed during this project. Sediment depth will be monitored and measured.

Outcome 2: Enhanced collection of sediment accumulation data will provide location-specific information on the performance of vetiver/native species sediment traps. This can used to estimate sediment capture for additional 8-10 sediment traps installed (Activity 1), and used to inform sediment trap construction in future projects.

Activity 3: Maintenance will be performed as needed on the ~30 existing vetiver/native species sediment traps already installed in kickouts in the Honokōwai watershed.

Method 3: An adaptive management approach will be utilized to prioritize maintenance operations.

Maintenance operations will include trimming vetiver plants to stimulate prolific root growth as well as the repair and replacement of plants in gaps that may have formed within the sediment traps. 

Outcome 3: Improved performance of existing vetiver and native species sediment traps. Measurable increases in sediment retention and holding capacity within existing kickouts. 

Activity 4: Coordination with West Maui R2R and Natural Resources Conservation Service on funding activities (PL-566) for the orifice retrofit at Honokōwai Dam #8. Objective: the dam can retain fine clay and silt from being transported to the reefs in West Maui. 

Method 4: Ridge to Reefs and partners have already completed a 60% partial design through coordination with Maui County and Hawaii Department of Lands and Natural Resources (DLNR) Dam Safety. With support from R2R and Ridge to Reefs, NRCS has completed an internal proposal through (PL-566) for permitting and full design which will inform the total project cost and next steps. RTR will continue to provide technical support and assistance to ensure the project’s timely progression.

Outcome 4: When completed, this activity will result in a “shovel-ready” project for the Honokōwai Dam #8 Retrofit as well as a full understanding of the total costs involved.