The following words and terms, when used in this chapter, shall have the following meanings, unless the context clearly indicates otherwise:

1. (1) Dam--Any barrier, including one for flood detention, designed to impound liquid volumes and which has a height of dam greater than six feet. This does not include highway, railroad, or other roadway embankments, including low water crossings that may temporarily detain floodwater, levees designed to prevent inundation by floodwater, closed dikes designed to temporarily impound liquids in the event of emergencies, or off-channel impoundments authorized by the commission in accordance with the Texas Water Code, Chapter 26, or the Texas Solid Waste Disposal Act, Texas Civil Statutes, Article 4477-7.
2. (2) Effective crest of the dam--The elevation of the lowest point on the crest of the dam excluding spillways.

3. (3) Existing dam--

   1. (A) any dam constructed in accordance with necessary authorizations of the commission;
   2. (B) any existing dam exempt under the Texas Water Code, §11.142.
4. (4) Height of dam--The vertical distance from the effective crest of the dam to the lowest elevation on the centerline or downstream toe of the dam, including the natural stream channel.
5. (5) Maximum storage capacity--The volume of the impoundment created by the dam at the effective crest of the dam, usually expressed in acre-feet.
6. (6) Normal storage capacity--The volume of the impoundment created by the dam, at the lowest uncontrolled spillway crest, usually expressed in acre-feet.
7. (7) Probable maximum flood (PMF)--The flood magnitude that may be expected from the most critical combination of meteorologic and hydrologic conditions that are reasonably possible for a given watershed.
8. (8) Probable maximum precipitation (PMP)--Theoretically, the greatest depth of precipitation for a given duration that is physically possible over a given size storm area at a particular geographical location at a certain time of the year.
9. (9) Proposed dam--Any dam, constructed or to be constructed, which is not included in the definition of existing dam.
10. (10) Spillway design flood (SDF)--The flood criteria that needs to be considered in the design of a proposed project.
11. (11) Spillway evaluation flood (SEF)--The flood criteria that needs to be considered in the hydrologic evaluation of an existing structure.

Source Note:The provisions of this §299.1 adopted to be effective May 13, 1986, 11 TexReg 1978.