View source for Log pond

{{Short description|Body of water for storage of wooden logs}}
[[File:Sugar Pine Mill Log Pond Full Deck.jpg|thumb|A "full deck" of logs awaiting the mill.]]
A '''log [[pond]]''' is a small natural [[lake]] or [[reservoir]] used for storage of [[wooden log]]s in readiness for milling at a [[sawmill]].  Although some [[mill pond]]s served this purpose for water-powered sawmills, steam-powered sawmills used log ponds for transportation of logs near the mill; and did not require the elevation drop of [[watermill]] reservoirs.
==Background==
[[File:American sawmill, circa 1920.jpg|thumb|upright|Log being hoisted from a log pond into the sawmill.]]
The earliest mechanized sawmills of the industrial revolution were built on navigable [[river]]s, lakes, or [[estuaries]] where logs could be floated to the sawmill and [[lumber]] could be carried to markets aboard [[ship]]s or [[barge]]s.  Early steam sawmills included a [[hoist (device)|hoist]] to lift logs out of the water onto a carriage which moved the log past a stationary powered saw.  Men could relatively easily push floating logs into position to be lifted by the hoist.  [[Forest]]s distant from navigable water became accessible with the development of [[railroad]]s.  Sawmills adjacent to navigable waters were termed cargo mills, in contrast to interior rail mills relying upon railroad transportation of logs and lumber.  Until [[tractor]]s powered by [[internal combustion engine]]s were powerful enough to move logs, ponds were required to simplify movement of logs from storage to the sawmill hoist.  Storage of logs in water has the additional advantages of minimizing fire risks, washing away dirt which could dull saws, and preventing splitting of logs which might otherwise dry prior to milling.  Cargo mills typically used a system of floating [[log boom]]s to contain stored logs from delivery until milling.<ref>Oakleaf pp.8,12&17</ref>
==Log pond operation==
Rail mills were built adjacent to small ponds when possible, but log ponds were often constructed by building a dam on a small [[stream]] where no suitable natural pond was available.  Risks of periodic flood damage discouraged use of larger rivers for log ponds, but water might be diverted or pumped from a larger river to maintain water levels in an adjacent log pond.<ref>Oakleaf pp.12&17</ref>  A railway spur would be built to a {{vanchor|log dump}} where logs might be rolled or hoisted off [[flat car]]s into the pond.<ref>Carranco pp.120&171</ref>  Log ponds were constructed with surface area allowing floating storage of the inventory of logs required to maintain sawmill production through periods when [[logging]] or rail deliveries might be interrupted.<ref>Oakleaf p.8</ref><ref>{{cite book |last=Johnston |first=Hank |date=1968 |title=Thunder in the Mountains: The Life and Times of Madera Sugar Pine |page=11  |publisher=Trans-Anglo Books |isbn=0-87046-017-X}}</ref>
Log ponds are convenient water reservoirs for [[firefighting]] at sawmills; and for routine cooling and lubrication of saw blades and other mill machinery.  [[Stormwater]] runoff from the mill yard and [[wastewater]] generated within the sawmill often flow into the log pond as the lowest point adjacent to the sawmill.  [[Boiler blowdown]], [[kiln#Wood-drying kiln|lumber drying kiln]] condensate, and exhaust steam from sawmill machinery sometimes kept a log pond from freezing during cold weather.<ref>Oakleaf pp.10,12&17</ref>
<gallery class="center">
Sugar Pine Mill Log Pond.jpg|A log pond supplied by railway in [[Sugar Pine, California]] around 1920.
Leona, Oregon.jpg|Splash of logs being dumped into a log pond
</gallery>
==Environmental considerations==
Log ponds are convenient reservoirs for water recycling in applications including [[hydraulic debarker]]s or [[dust suppression]].  Log ponds offer some wastewater treatment similar to a [[settling basin]] and [[facultative lagoon]].  Log pond overflow during [[Precipitation (meteorology)|rainfall]] and [[snowmelt]] may contain floating pieces of wood and bark, dissolved organic compounds leached from wood, and suspended particles of sawdust and soil.  The [[United States Environmental Protection Agency]] published wet storage category effluent limitations in the 1970s prohibiting discharge of floating woody debris and requiring log pond overflow pH to be between 6 and 9.<ref>[http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=b26610351b9ea26a417a7f7aed953490&rgn=div5&view=text&node=40:31.0.1.1.5&idno=40 40CFR429.100] {{Webarchive|url=https://web.archive.org/web/20100621232438/http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=ad6ede56e58f4c393417779ae901b4a3&rgn=div5&view=text&node=40:31.0.1.1.5&idno=40 |date=2010-06-21 }} Accessed 2012-09-17</ref>
==Sources==
* Carranco, Lynwood ''Redwood Lumber Industry'' Golden West Books, San Marino, California (1982) {{ISBN|0-87095-084-3}}
* Oakleaf, H.B. ''Lumber Manufacture in the Douglas Fir Region'' Commercial Journal Company, Chicago
==Notes==
{{reflist}}
==External links==
*[https://www.youtube.com/watch?v=_-0lHyYImf8 The Finlaystone Timber Ponds on the River Clyde.Video footage]
{{pond}}
[[Category:Ponds]]
[[Category:Sawmill technology]]