Based on the Chicago pattern we have adopted average rates of population growth for Harris County for the next five census decades approximating as follows: 4.25, 3.4, 3.1, 1.6, and 0.8 percent. These rates of growth result in an estimated population for Harris County of 4,900,000 in 2010, 53 years after Harris County reached a population of 1,157,000. The Chicago metropolitan district reached a population of approximately 4,900,000 in 53 years after it had a population of 1,157,000.

It is believed that the growth factors applicable to the Chicago metropolitan district are much more similar to those applicable to Harris County than is the case with the larger cities on the eastern seaboard of the United States. Houston's population has already surpassed or is fast approaching the populations of Cleveland, Pittsburgh, St. Louis, and San Francisco. The only urban centers, other than Chicago, which could be of any guidance in estimating the future population of Harris County are Los Angeles County and the Detroit metropolitan district. Except for the depression years, 1930-40, the growth pattern of the Detroit metropolitan district since it reached Harris County's present population is very similar to that of the Chicago metropolitan district. If the population growth of Harris County should follow that of Los Angeles County after the latter reached a population of 1,170,000, Harris County will have a population of 5 million by about 1990. These various rates of population growth are shown graphically on the chart with the heading, "Harris County Population."

The per capita domestic water use in Harris County was almost exactly 100 gallons per day in 1957 and, on an average, has been increasing annually at a somewhat faster rate than 1 gallon per day. We estimate that the per capita domestic use of water in Harris County will continue to increase annually at not less than 1 gallon per day until such use reaches 155 gallons per day in 2010. Based on the foregoing considerations, we therefore estimate the domestic water use in Harris County as follows:

6. Industrial use of domestic quality water in Harris County

A part of the industrial water is distributed through the municipal distribution systems together with the water for domestic use. Practically all of the industrial consumption of fresh water in Harris County, which cannot be fed from separate industrial water canals, must come from wells and from the municipal supply canals and domestic water distribution systems. This practice is followed in practically all of the larger cities of the United States even though they be located adjacent to large supplies of water. The Chicago industries within reach of the municipal water distribution system take their industrial water consumption from the municipal distribution system. This is true at St. Louis, the only substantial exception being the use of well water by the breweries. The consumptive use of industrial water at New Orleans comes from the municipal distribution system where the industries are in reach of such system and, in small part, from wells.

By and large the municipal water distribution systems in Harris County cover or will cover the areas within the city limits of the municipalities in Harris County, the present limits of the municipalities being indicated on the accompanying map of water use areas in Houston vicinity.

In estimating the future industrial water demand in Harris County which must come from wells or from the domestic water supply and distribution systems, it would not be safe to assume that the well supply and the domestic surface supply will not be called on for all of the industrial water use in Harris County except for the industrial use in southeastern Harris County which can be supplied from canals and raw water distribution systems separate and apart from the domestic water supply system.

Presently, Harris County industries are using approximately 100 million gallons per day from private wells. It is assumed that such well water use by industries will continue indefinitely into the future and will continue to be a charge against the overall supply of domestic quality water available to Harris County.

The city of Houston is supplying some 50 million gallons per day of untreated San Jacinto River water from the end of its Lake Houston canal through a 60inch conduit and tunnel (two 30-inch pipes in tunnel) under the ship channel to the industrial water distribution system of certain industries on the south side of the ship channel. (See accompanying map.) The city has contracted to supply up to 75 million gallons of water per day to these industries. One of the large users of this water is a paper manufacturing plant, the nature of whose operations will probably continue to require domestic quality water from wells and from the San Jacinto River supply. It is assumed that the water requirements of the existing industries along the south side of the ship channel will continue to be furnished from wells and from the San Jacinto River up to 75 million gallons per day. The future additional industrial water requirements of this area could be backed in through the cities of Deer Park and Pasadena from a separate canal system.

The San Jacinto River Authority has assumed the responsibility for delivering the surface water requirements of the San Jacinto River Basin east of the San Jacinto River as well as the surface water requirements of the San Jacinto River watershed above Lake Houston. It has contracted to furnish the Humble refinery with 25 MGD (million gallons per day) and presently has a surplus of 25 MGD of firm supply immediately available for sale in the Baytown area. The authority has had prepared preliminary plans for a gravity canal from its Highlands Reservoir to Cedar Point, with a capacity of 50 MGD, and has offered water for the use of a proposed Cedar Point steelmill at approximately the same price at which water is now being sold the Humble refinery by the authority.

The Humble refinery has not found it necessary to clarify or otherwise treat the San Jacinto River water delivered to it through the unlined canal although some trouble has been caused by turbidity, evidently caused by fish stirring up mud in the Highlands Reservoir. The authority expects to line with concrete its main canal from Lake Houston to the Humble refinery and to provide a bypass around the Highlands Reservoir at such time as it becomes necessary to enlarge the capacity of its main canal.

The San Jacinto River Authority proposes to furnish water in the CrosbyBaytown-Cedar Point area suitable for domestic use after filtration as well as industrial water with a minimum of dissolved solids, hardness, and turbidity.

In order to estimate the future industrial use of domestic quality water in Harris County, it is therefore necessary to break down the estimated total industrial water requirements into well water use and into areas of use of surface water. The Houston Chamber of Commerce has already made practical estimates of the industrial water demand in the Houston area (see outline on accompanying map of Houston area as defined by the chamber of commerce) through 1975, the surface water requirements being broken down into use in the Houston-Pasadena area, use in the Baytown-La Porte area, and use by new industries. The Bureau of Business Research of the University of Texas has also made estimates of industrial use, through 2010, by types of industries in the Houston node (Harris County less precincts 5, 6, and 7 in northwestern Harris County plus Chambers County precinct 5 which lies west of the Trinity River). We have made corresponding estimates of industrial water demand by applying, to the hereinabove estimated Harris County populations, a per capita industrial water use which gradually increases from the present 150 gallons per day to 210 gallons per day in 2010. The three estimates are given in the tabulation below.

It is to be noted that, after correcting the chamber of commerce estimates by the 30 MGD lag (estimated 1957 use less actual 1957 use), the three estimates for the year 1975 are almost exactly the same, and that the two estimates which run to 2010 are approximately the same for the year 2010.

For the purposes of this study, we are adopting the chamber of commerce estimates of industrial water use through 1975 after deducting the 30 MGD lag in use and are adopting the Bureau of Business Research estimates after 1975. The various estimates of industrial water use are given in the tabulation on the following page together with our breakdown into (a) well water use and surface water use by areas of use and (b) sources. The breakdowns follow as closely as possible the chamber of commerce's more general breakdown.

Estimates of industrial water demand in Houston area-Annual daily average in million gallons

Houston Chamber of Commerce estimate does not extend beyond 1975.

2 Adopted totals.

7. Water use in upper San Jacinto River watershed

It is anticipated that as Houston and Harris County grow there will also be a substantial increase in population and water use in the upper San Jacinto River watershed particularly in the Conroe-Cleveland-Huntsville area adjacent to the proposed reservoirs in the upper watershed. The Cleveland and Huntsville precincts and Montgomery County, including Conroe, had a population of approximately 52,000 as of 1957, or 42 percent of the Harris County population. This percentage is expected to increase in the future as Harris County becomes more saturated from a population standpoint.

It is assumed that the main centers of water consumption will be in the vicinities of Conroe, Cleveland, and Huntsville which had a combined population of approximately 29,200 in 1957. The average annual increase in the combined population of the three towns has been 4.33 percent for the 47 years, 1910-57, and 5.64 percent for the 17 years, 1940-57. Although the annual growth rates of large central metropolitan cities tend to decrease, the satellite towns tend to keep on growing at a uniform annual rate of increase until they too reach a point of population saturation. Water should be provided to permit of a continued population growth in the three towns at an annual rate of some 5 percent per annum. This results in an estimated combined population in the vicinities of the three towns of 388,000 in 2010 or somewhat less than 8 percent of the estimated Harris County population of 4,900,000 in 2010.

The per capita use of water in the three towns averaged approximately 105 GPD (gallons per day) in 1957 of which some 80 GPD were probably nonindustrial use. We estimate that this per capita use of nonindustrial water will probably increase at the rate of one GPD per annum. With the provision of an ample supply of high quality surface water it is believed that the towns will find it advisable by about 1965 to switch from well water to surface water in order to supply treated surface water to industries in the vicinities of the three towns. Also, with the provision of ample supplies of lake water, it is believed that industries may be attracted to the area to the extent of a per capita use of at least 100 GPD as compared with a 1957 per capita use of industrial water in Harris County of 150 GPD. Allowance should be made for an annual increase in per capita use or industrial water of one GPD.

Mr. Roy Seaburg has permits for and is using 1.4 MGD for irrigation purposes. We have included 2.0 MGD for this use and riparian uses in the estimates of uses in the upper watershed.

Based on the foregoing considerations the estimated water demand in the upper watershed is given in the following table:

8. Summary of requirements for domestic quality water The various estimated requirements for water of domestic quality in the San Jacinto River Basin, both from well and surface sources, are summarized in the following tabulation and are shown graphically, together with the historical water use in the Houston area since 1935, on the accompanying chart, "Estimated Demand Curves for Domestic Quality Water in San Jacinto River Basin."