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Mill |
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Monetary cost and billing unit used by utilities; equal to 1/1000 of U.S. dollar (equivalent to 1/10 of one cent). |
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Million acre-feet |
maf |
The volume of water that would cover 1 million acres to a depth of 1 foot |
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Millisecond delay |
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A type of delay cap with a definite but extremely short interval between initiation and explosion |
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Minimum flow |
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Negotiated lowest flow in a regulated stream that will sustain an aquatic population of agreed-upon levels. Flow may vary seasonally. |
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Mitigation |
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Action taken to avoid, reduce the severity of, or eliminate an adverse impact. |
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Modification/Repair Type |
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A data field used to summarize the type of modification (change to a dam) or repair (work performed to remedy damage that occurred to a dam or its apputenances) that was implemented. |
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Modified homogeneous earthfill dam |
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A homogeneous earthfill dam that uses pervious material specially placed in the embankment to control seepage. See embankment dam.
Modified Mercalli scale. An earthquake intensity scale which has twelve divisions |
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Modified Mercalli scale |
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An earthquake intensity scale which has twelve divisions ranging from I (not felt by people) to XII (nearly total damage). For more information on the modified Mercalli scale, visit the U.S. Geological Survey National Earthquake Information Center. |
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Moisture content |
water content |
The ratio of the weight of water in a soil sample to the weight of the dry soil, expressed as a percentage. See optimum moisture content. |
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Monomictic lakes |
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Warm- water lakes which turn over annually, usually in winter, and where the temperature never falls below 4 degrees C. |
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Morning glory spillway |
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A circular or glory hole form of a drop inlet spillway. Usually free standing in the reservoir and so called because of its resemblance to the morning glory flower. |
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MS connectors |
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Surface delays for use when shooting with detonating cord. |
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Multiple arch dam |
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A buttress dam, the upstream part of which comprises a series of arches. |
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Multiple-purpose reservoir |
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A reservoir planned to operate for more than one purpose. |
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Multipurpose dam |
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A dam constructed for two or more purposes (e.g. storage, flood control, navigation, power generation, or recreation.) |
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Nameplate |
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Power generation capacity of a generator that can be guaranteed under continuous operation. |
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NATDAM ID |
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Identification number assigned to a dam in the U.S. National Inventory of Dams. |
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National Weather Service |
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Please visit the website:
http://www.nws.noaa.gov |
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Natural frequency |
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The natural frequencies of a structure are the frequencies of free vibration. Free vibration is vibration that occurs in the absence of forced vibration. In a structure undergoing vibration, a mode of vibration is a characteristic pattern (shape) assumed by the structure in which the motion of every particle is simple harmonic motion with the same frequency. The fundamental mode of vibration of a structure is the mode having the lowest natural frequency |
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Natural period of vibration |
T |
The period of vibration of a a structure is the time required for one cycle of the simple harmonic motion in one of these characteristic patterns (shapes). T = 1/f. |
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Naturalness |
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Area which generally appears to have been affected primarily by the forces of nature, with the imprint of man's work substantially unnoticeable. |
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Neatlines (of structure) |
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A line which defines the limits of work, such as an excavation, cut stone, etc. Also, the true face line of a building regardless of the projections of the stones; a line back of, or inside of, incidental projections. Any material removed beyond the neat line is overbreak. |
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Neotropic migrant |
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A bird that migrates to tropical regions during the winter. |
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Net economic benefits |
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Economic benefits less economic costs. |
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NID Core Type |
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The watertight or impermeable part of a dam.
Types include: Bituminous Concrete, Concrete, Earth, Metal, Plastic, Unlisted/unknown.
Core positions include: Upstream Facing, Homogenous Dam, Core, Unlisted/unknown.
Core certainty is listed as Known or Estimated. |
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Non-reimbursable |
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Cost of constructing, operating, or maintaining a Reclamation project that is borne by the Federal taxpayer and is not reimbursed by any other individual, entity, or organization. |
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Non-uniform flow |
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The velocity varies with position. |
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Non-utility generators |
NUG's |
Facilities for generating electricity that are not owned exclusively by an electric utility and which operate connected to an electric utility system. |
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Nonconsumptive water uses |
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Water uses that do not substantially deplete water supplies, including swimming, boating, waterskiing, fishing, maintenance of stream related fish and wildlife habitat, and hydropower generation. |
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Nonfirm power |
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Power that is not available continuously and may be interruptible. This power may be marketed on a short-term basis. |
