{{Short description|Marsh in Sonoma County, California, United States}} '''Ledson Marsh''' is a {{convert|30|acre|km2|1|adj=on}} freshwater marsh in Annadel State Park east of Santa Rosa in Sonoma County, California, United States. Located on the east flank of Bennett Mountain, it drains into Schultz Creek, a tributary of Yulupa Creek.
thumb|200px|A remnant of Ledson Marsh near the end of the dry season ==Earthen dam== The marsh was formed by an earthen embankment dam about {{convert|300|ft|m}} long, constructed in 1930 by a former landowner. The dam is about {{convert|6|ft|m|0}} high and {{convert|4|ft|m|1}} wide at its crest. Over the years, the dam deteriorated, allowing water to seep through it and causing the marsh to dry out in the autumn and refill during the winter rains. The deterioration was partly due to rodent holes and partly due to stumps left by the felling of eucalyptus trees that were planted on both sides of the embankment.<ref name=IRWMP>{{cite web|url=http://bairwmp.watershedportal.net/doc_import/WM-HPR/1_High%20Priority/Ledson_Marsh_Restoration_Annadel_State_%20Park_IRWMP.doc|title=Ledson Marsh Restoration: Annadel State Park (draft)|accessdate=2009-02-01|archive-url=https://web.archive.org/web/20110724124651/http://bairwmp.watershedportal.net/doc_import/WM-HPR/1_High%20Priority/Ledson_Marsh_Restoration_Annadel_State_%20Park_IRWMP.doc|archive-date=2011-07-24|url-status=dead}}</ref>
There was concern over the dam's safety. A catastrophic dam failure would destroy the marsh habitat and clog various Sonoma Creek tributaries with sediment. The California Department of Parks and Recreation therefore repaired the dam in such a way as to preserve the marsh's seasonality. <ref name=IRWMP/>
;California red-legged frogs Because of its seasonality, the marsh was colonized by California red-legged frogs (''Rana draytonii''), a federal- and state-listed threatened species. Government agencies grew concerned that if the marsh did not dry out every year, bullfrogs might establish themselves in the marsh, displacing the red-legged frogs. <ref name=IRWMP/>
thumb|right|Ledson Marsh in 2006
==Recreation== The marsh is a picnicking and bird-watching spot, and also used for mountain bicyclists, hikers, joggers, and equestrians.<ref>{{cite book|title=Mountain Biking the San Francisco Bay Area: A Guide to the Bay Area's Greatest Off-Road Bicycle Rides|last1=Jackson|first1=Lorene|year=2004|publisher=Globe Pequot|isbn=0-7627-2715-2|page=62}}</ref>
{{Coord|38.4085|N|122.5997|W|source:gnis-1799538_region:US-CA_type:waterbody|display=title|notes=<ref>{{Cite gnis|1799538|Ledson Marsh}}</ref>}}
==See also== *Annadel State Park *Lake Ilsanjo
==References== {{reflist}}
==External links== {{commonscat|Annadel State Park}} * [http://jackhines.com/Annadel_Frogs.htm Sound recording of California Red-legged Frog chorus at Ledson Marsh] * [http://www.bioone.org/doi/full/10.1655/0018-0831(2007)63%5B430%3AMUOTCR%5D2.0.CO%3B2 Microhabitat use of the California Red-Legged Frog and introduced bullfrog in a seasonal marsh]
Category:Marshes of California Category:Landforms of Sonoma County, California Category:Wetlands of the San Francisco Bay Area