alleviation plans Following public consultation in 2014, design work was due, as of 2016, on a plan focused on excess water storage options, primarily at Tymon Park, and the use of flood walls. In 2020 there were public meetings about the resulting Flood Alleviation Scheme, a planning application was submitted to An Bord Pleanala by the two local authorities together, and a further submission prepared in response to a request for further information by An Bord. The final flood alleviation scheme has as main features: design to manage a 100-year flood, with 40–60% culvert obstruction, embanking in both divisions of Tymon Park, including a flood interception area in the eastern division, and a flow control device at the outlet from Tymon Lake, formation of an Integrated Constructed Wetland near Tymon Lake, flood wall construction in multiple locations, water capture engineering in one park in the Kimmage area near Crumlin, channel realignment in Whitehall Park, manhole upgrading and potentially sealing in multiple locations, including near South Circular Road and within Temple Bar. Nature The river rises at an altitude of c. 92m, passes through Tymon Park at around 60m, and runs steadily downhill to sea level before the Grand Canal, after which it flows on to the Liffey at that level. Despite its historical importance, it is not one of the larger volume tributaries of the Liffey, which has over 100 watercourses in its system, excluding the tributaries of the Dodder, but it is one of the best-known of the more than 135 rivers and streams within the historic County Dublin. The majority of the Poddle's flow comes from storm and surface water drainage. Historically, in addition to the partial capture of the Dodder flow, there was potential for snowmelt or storm "bursts" in the Dodder feed, but this possibility is now cut off. The river's catchment area is around 16.4 square kilometres, most of which is urbanised. The bedrock over most of the Poddle's catchment is a mix of limestone and shale, with some aquifer capacity, covered by limestone-derived till and gravel, and then by various gravels, alluvium and human-activity-derived soils. The river, due to limited flow, long-term issues with pollution, and barriers at the Liffey end, and the syphon under the Grand Canal, has no significant persistent fish population, and also lacked sensitive invertebrate species. Specifically, there are no salmon-like species, and no other fish of fisheries interest and