KAILUA — Windward waterways, wetlands and ocean waters could be enhanced under a bill in the Legislature.

House Bill 1898 would address water quality and other issues facing Kailua waterways. It calls for restoring water flow from Kawai Nui Marsh to Kawai Nui Stream, studying the effectiveness of opening the stream mouth at the ocean and reducing polluted runoff into Ka'elepulu Pond.

The bill was introduced by Rep. Pono Chong, D-49th (Maunawili, Olomana, Enchanted Lake, Kane'ohe), and is the result of a three-year effort to study and improve the quality of the water that flows from the land to the sea, Chong said.

The Senate Water and Land Committee has scheduled a hearing on the bill at 3:15 p.m. today in Capitol conference room 224.

The measure looks at two water systems that both have consequences at Kailua Beach Park.

The first is Kawai Nui Stream, which flows from Kawai Nui Marsh and empties at Kailua Beach Park. The second is the Keopu flood control basin that collects water from Norfolk, Keolu Hills and Enchanted Lake in the privately owned Ka'elepulu Pond, which then outlets through Ka'elepulu Stream.

"The problem is ... both the city and the state dump runoff in (the pond) that leads into the public system of the Kailua waterways," Chong said.

Problems mounted as the result of the development of Enchanted Lake subdivision and a flood control dike between the marsh and Kailua homes in the 1960s.

Ka'elepulu Pond was once a 400-acre, 3-foot-deep wetland and was shrunk to a 100-acre, 12- to 18-foot-deep lake, said Bob Bourke, an Enchanted Lake Residents Association board member and environmental scientist at Oceanit. In order to get the permit for the Enchanted Lake project, the developer agreed to allow the city to drain into the lake, which was then owned by Bishop Estate.

Silt and debris have been filling the pond for 50 years. Major runoff from Norfolk, Keolu Hills and Enchanted Lake drain to the Keopu flood control basin that flows into the lake. In addition, there are 37 other city drains sending water there.

HB 1898 would initiate three of 11 recommendations from a study that evaluated Kailua waterways. First, it asks the state Department of Land and Natural Resources to modify the basin to have it capture silt and pollution before they can flow into the lake, Bourke said.

"I've got pictures showing 50 tons of rock coming down a single drain in a single storm event," he said. "It's like a double garage full of rock."

In some places, islands have formed in the lake and vegetation is growing. Parts of the lake are too shallow for boats, and the fear is that one day the area, where endangered Hawaiian water birds nest, will be lost.

The second initiative would hire an engineer to figure how best to restore water flow from Kawai Nui Marsh to Kawai Nui Stream. The flood control dike blocked the natural flow from the marsh to the stream, which now dead-ends at Kaha Street, Bourke said. The stream flows behind homes on Kihapai Street through Hamakua Marsh, behind homes on Papalani Street to Ka'elepulu Stream and out to the ocean at Kailua Beach Park.

Often the ocean end is also blocked by sand buildup, creating stagnation and poor water quality, said Bourke, who measured oxygen levels in the stream and found zero oxygen halfway down the stream.

"That entire branch of Kawai Nui Stream is a dead-end sump," Bourke said. "Unless it rains and water comes into it from street drains, it doesn't flow at all. The water becomes stagnant. It's highly nutrified from runoff, and basically things get in there and they rot."

The third initiative in the bill asks the DLNR and the Department of Health to help the city find a more effective means of opening the stream mouth at Kailua Beach Park and for DOH to spend money to study the public health aspect of having stream water flowing out on the beach.

Ka'elepulu Pond residents have sought government help with the lake for decades, arguing that it channels runoff into the water system, bringing siltation and debris from hillsides, streets and neighboring property.

"City storm drains all flow into the lake and into the stream and are responsible for the mess on the beach," said Kathy Kelly, president of the Enchanted Lake Residents Association. "We have to get mutual agreement that just because the lake is private property does not mean that we have to be responsible for everything flowing into it."

Reach Eloise Aguiar at eaguiar@honoluluadvertiser.com.