water stream over rocks


Assessment and Protection Plan for the Nawiliwili Watershed

Assessment and Protection Plan for the Nawiliwili Watershed

State Health

10/01/01 - 08/31/04


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A team of researchers from the University of Hawaii's Water Resrources Research Center (WRRC) worked on an EPA/DOH-sponsored project to assess the Nawiliwili Bay watershed on Kauai for pollution sources. The project was funded under EPA's section 319 Nonpoint Source Management Program.

Section 319 Nonpoint Source Management Program:

Congress amended the Clean Water Act (CWA) in 1987 to establish the section 319 Nonpoint Source Management Program because it recognized the need for greater federal leadership to help focus State and local nonpoint source efforts. Under section 319, State, Territories, and Indian Tribes receive grant money which support a wide variety of activities including technical assistance, financial assistance, education, training, technology transfer, demonstration projects, and monitoring to assess the success of specific nonpoint source implementation projects.

Why Nawiliwili?


The Nawiliwili watershed is the most urbanized on Kauai, draining a large part of Lihue. Several of the streams that empty into Nawiliwili Bayalso wind through large areas of agricultural land (both animal pasture and sugarcane). The bay itself is fairly enclosed, owing, in part, to the presence of a long breakwater across the bay. This limits the amount of flushing with open ocean water that can occur.

Furthermore, Nawiliwili Bay is a popular and well used recreational area. Kalapaki Beach is a readily accessible, family friendly resource for the residents of the Lihue area.

In 1997, Nawiliwili Bay was included in the list of water quality limited segments (WQLS) that the state health department (DOH) based on observations of turbidity and heavy metals.

Water Quality Limited Segments*:

"Water Quality Limited Segments" are defined in Section 303 of the Clean Water Act and EPA regulations as water areas where existing water quality does not meet, and will not meet, applicable water quality standards even after effluent limitation requirements on point source discharges are applied.

Click here to review the State's process for including a water body in the list of WQLSs.

Impaired waterbodies of the State are designated in several plans: State 303(d) List, State 305(b) Report, and Clean Water Act Section 208 Water Quality Management Plans (WQMP) for all four counties.

Each coastal water segment is linked with an associated land area. Each island is divided into hydrographic areas based on surface topography. Subareas are defined by the related drainage area, stream system, geography, and coastal water segment. A coastal water quality limited segment coincides with those coastal waters that receive discharges from point and nonpoint sources located within that defined area.

The segments have been designated by the Department of Health based on common
hydrological characteristics, existing water quality, and waterquality standards.

Population distribution, sewer districts, and water distribution were also used to determine segment boundaries. Segment designation as a Water Quality Limited Segment reflects the amount of flow, type and quantity of pollutants, the degree of violation of water quality standards, and the interactive and dispersive capacity of the receiving waters. In addition, consideration is given to public health hazards, the actual uses of the receiving waters, the impediments to controlling pollutant discharges, and compliance with water quality limited and effluent limitation requirements, based on the best available data and information. In every instance, the reason a segment is designated as a Water Quality Limited Segment is due to the high pollution emissions discharged by nonpoint sources.

Section 319 was added to the Clean Water Act in 1987 specifically to addresses nonpoint sources of pollution. It requires each state to identify navigable waters which, without additional action to control nonpoint sources of pollution, cannot reasonably be expected to attain or maintain state water quality standards. Since nonpoint source pollution is the reason for designation of specific waterbodies as Water Quality Limited Segments, all waterbodies in Hawaii to be identified under the Section 319 requirement are Water Quality Limited Segments.

The Water Quality Limited Segments identified by Department of Health in 1973 to meet the requirements of Section 303(d) of the Clean Water Act were later incorporated into State of Hawaii reports required by Section 305(b) of the Clean Water Act. These biennial 305(b) reports are the mechanism by which states report on the status of their water quality. The report describes the nature and extent of state water pollution and, along with other requirements, identifies Water Quality Limited Segments. Hawaii's most recent 305(b) report (1998) identifies 18 Water Quality Limited Segments in the State (see Table 1-5 and Figure 1-1)*.

The 18 segments were selected by Department of Health from areas where the State had sufficient information to make judgments about water quality. Two levels of assessments were used: segment identification based on ambient water quality monitoring, and segment identification based on other information. Areas not identified as Water Quality Limited Segments are identified as Effluent Limited Segments and are assumed to meet or will likely meet applicable water quality standards after point source discharge controls are applied. This list is reviewed every two years as required by Section 303(d), Clean Water Act. In January 1996, the Department of Health began soliciting nominations from the public for impaired waterbodies, and conducting an assessment on each nominated waterbody."

*This information was taken from the DOH Clean Water Branch website*

Scope of the Project

Click here for the detailed scope of work

The research team developed an assessment and protection plan for the Nawiliwili watershed in three phases. In Phase 1, we sought out, validated, and documented existing environmental data. In Phase 2, we identified the sources of pollution and contamination in the Nawiliwili Watershed. In Phase 3, we prepared a watershed restoration and protection plan for the Nawiliwili watershed for submission to the state.

Project Task


  • Data Collection

As of 4/15/02, we had identified sources of data on water quality in the Bay and the streams, and getting whatever data we can from these sources. We have identified the following data sources and have extracted as much data as possible from them regarding the Nawiliwili watershed and Bay.


Source Type of Data
State Health Department bacteriological data at several sites in the Bay and streams
USEPA STORET Database various water and sediment chemistry data in the Bay and in streams
State GIS data page GIS layers of many types including streams, roads, topography, land use, and rainfall