Section 830. Surface water sources; quantity; quality; development structures

A. A surface water source includes all tributary streams and drainage basins, natural lakes, and artificial reservoirs or impoundments above the point of water supply intake.

1. The quantity of water at the source shall:

a. Be adequate to supply the water demand of the service area;

b. Provide a reasonable surplus for anticipated growth; and

c. Be adequate to compensate for all losses, including evaporation, seepage, flow-by requirements, etc.

2. The safe yield of the source shall be determined as follows:

a. Simple intake (free-flowing stream). The safe yield is defined as the minimum withdrawal rate available during a day and recurring every 30 years (30 year - one day low flow). To generate the report for this, data is to be used to illustrate the worst drought of record in Virginia since 1930. If actual gauge records are not available for this, gauges are to be correlated from similar watersheds and numbers are to be synthesized; and

b. Complex intake (impoundments in conjunction with streams). The safe yield is defined as the minimum withdrawal rate available to withstand the worst drought of record in Virginia since 1930. If actual gauge records are not available, correlation is to be made with a similar watershed and numbers synthesized in order to develop the report.

Note: Local governments may request this aid from the State Water Control Board (SWCB) by contacting either the Health Department's Office of Water Programs or the SWCB's headquarters office in Richmond.

B. The owner shall conduct, or have conducted, a sanitary survey and a study of the factors, both natural and man-made, which will affect the quality of the water at the source. The results of the sanitary survey shall be submitted to the division. Such survey and study shall include, but shall not be limited to:

1. Obtaining samples over a sufficient period of time to assess the bacteriological, physical, chemical, and radiological characteristics of the water;

2. Determining future uses and effects of impoundments or reservoirs;

3. Determining the degree of control over the watershed that may be exercised by the owner; and

4. Assessing degree of hazard to the source by possible spillage of materials that may be toxic, harmful, or detrimental to treatment processes.

C. Intake structures shall provide for:

1. Withdrawal of water from at least three levels in impoundments or reservoirs. Withdrawal of water from more than one level may be required in run-of-the stream intakes if the quality varies with depth;

2. Separate facilities for release of less desirable water held in storage;

3. Screens on intake ports with provisions for adequate cleaning;

4. Prevention of flooding of access walkways and control valves of intakes on multiple purpose reservoirs; and

5. Velocity of flow through inlet structure such that frazil ice will be held to a minimum.

D. A detention reservoir is a structure into which water is stored for pretreatment to improve water quality prior to other treatment. Where a detention reservoir is required, the development shall assure that:

1. Water quality is protected by controlling runoff into reservoir;

2. Dikes are structurally sound and protected against wind action and erosion;

3. Point of influent flow is separated from the point of withdrawal; and

4. Sufficient detention time is provided in the reservoir as recommended by the designer and approved by the division.

E. In order to protect the public health and guarantee a supply of pure water, terminal reservoirs shall not be utilized for body contact recreation and boats powered by gasoline engines. Large terminal reservoirs may be used for body contact recreation and boats powered by gasoline engines provided a buffer zone acceptable to the division and water purveyor is furnished. Site preparation shall include but not be limited to the removal of brush and trees to the high water elevation, and protection from floods during construction.

Historical Notes

Derived from VR355-18-008.02 § 3.20, eff. August 1, 1991; amended, Volume 09, Issue 17, eff. June 23, 1993.

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.