The City Council voted its approval Tuesday night of the most costly public works project in Kaysville's history - a $10 million two-year project to bring irrigation water to all of its residents.

The project has been discussed for several years but received new life during last summer's drought when residents were asked to cut back their use of culinary water, especially on lawns and gardens.The city completed a new water master plan in June 1988 that recommends irrigation or untreated water be made available to all homes and businesses not currently served by a system.

Using irrigation water for non-culinary uses such as watering lawns and gardens will ease the demand on the city's treated water supply, City Manager John Thacker said, estimating the city's existing drinking water supplies will be sufficient until 2010 at current growth rates.

The project is a joint development between Kaysville and the Davis and Weber Counties Canal Co., which owns water rights from the Weber River and serves communities from Kaysville north to Riverdale in Weber County.

Under the proposal, the canal company will build a water storage tank in south Layton and a transmission line along Fairfield Road into Kaysville. A second storage tank and transmission line will be built in east Kaysville, near the Holmes Creek detention basin.

The city will install the distribution system, Thacker said, and assume the responsibility for servicing the system and distributing the water.

Thacker said the canal company's share of the project will also serve parts of Layton and other communities and will cost between $35 million and $40 million. Kaysville's portion is estimated at $5 million, with the canal company spending a similar amount in the city.

The canal company has low-interest water development loan funds available to pay for the project, Thacker said. To repay the construction loans to the canal company, residents tapping into the system will pay a one-time hookup fee plus annual payments. The fees are on a sliding scale, based on lot size and the size of the water line connection.

Figures distributed by the city at a public hearing preceding Tuesday's council meeting show an average residence on a one-third-acre lot, will pay a one-time connection fee of $250 and an annual fee of $200 for one acre-foot of water.

The $200 annual fee includes $156 for debt service for building the system and the rest for storage and transmission costs.

A study of city water bills shows that residents could actually save money, city engineer Lee Cammack said during the hearing, attended by more than 50 residents. Using the increased culinary water rates the council approved last summer, Cammack said an average homeowner using treated water for outside use pays $326 per year.

By depending on irrigation water for watering gardens and lawns, Cammack said, he estimates most residents will drop to the city's minimum water use level of $10 per month for city water, or $120 per year.

That totals $320 annually for a combined culinary and irrigation system and stretches the city's existing drinking water resources into the next century, Cammack said.

Design work on the system is already starting and construction of the first phase could begin this summer. The first phase includes building the Layton storage tank and transmission line and city distribution lines east of I-15.

The second phase, planned for the summer of 1990, includes building the second storage tank in east Kaysville and extending distribution lines to the area west of I-15.

Thacker said Kaysville owns enough water shares in the two existing irrigation and canal companies to supply the expanded system.

Thacker also said he expects the Kaysville Irrigation Co., which supplies water to farmers, will eventually go out of business as the city's remaining agricultural areas are developed. The city will make a standing offer to buy that water, supplementing the shares it already owns, Thacker said.

By bringing in irrigation water and stretching the city's existing supply of drinking water to cover future growth, Thacker said Kaysville residents could save up to $13 million in water fees over the next two decades.