1.0 DCPLUS 20260729 20055000 20260729 20055000 https://www.arcgis.com/home/item.html?id=e5e8ab3d7d93427cb3a37b810d733479 e5e8ab3d7d93427cb3a37b810d733479 Feature Service https://services.arcgis.com/Ej0PsM5Aw677QF1W/arcgis/rest/services/NZMS_attribute_table_2026-07-29/FeatureServer https://www.arcgis.com/sharing/rest/content/items/e5e8ab3d7d93427cb3a37b810d733479/info/thumbnail/thumbnail1785422597519.png NZMS_attribute_table_2026-07-29 New Zealand mudsnailPotamopyrgus antipodarumKing Countyfreshwaternon-native speciesmonitoringbenthicinvertebrateinvasive speciessnail This layer illustrates where New Zealand mudsnails (Potamopyrgus antipodarum) have been found in benthic samples collected from streams throughout King County, and their most recent recorded relative abundance (in percent) at each site. Layer reflects information from samples collected through 2025. -122.622 -120.999 47.901 47.062 1 <span style='display:inline !important; float:none; font-style:normal; font-variant-caps:normal; font-variant-ligatures:normal; font-weight:400; letter-spacing:normal; text-align:start; text-decoration-color:initial; text-decoration-style:initial; text-indent:0px; text-transform:none; word-spacing:0px;'>The layer contains points where non-native New Zealand mudsnails (NZMS) have been collected in and around King County streams. Within King County, NZMS were first detected in Thornton Creek in 2009, and have since colonized over thirty streams throughout the County. The map includes data from samples collected by King County, as part of King County’s Freshwater Benthic Macroinvertebrate Monitoring Program Benthic macroinvertebrate monitoring program - King County, Washington, as well as samples from other agencies. The map shows sites where NZMS have been detected, and displays a recent relative abundance, calculated as the percent of the sample that was identified as New Zealand mudsnails. Alongside points indicating where NZMS have been collected, this map also includes sites where snails have been collected, but were only able to be identified to the superfamily of NZMS (Truncatelloidea) which also contains native freshwater snails. The data for this map were downloaded from the Puget Sound Stream Benthos database (https://pugetsoundstreambenthos.org/) in April 2026 and reflect samples processed through 2025.<span style='display:inline !important; float:none; font-style:normal; font-variant-caps:normal; font-variant-ligatures:normal; font-weight:400; letter-spacing:normal; text-align:start; text-decoration-color:initial; text-decoration-style:initial; text-indent:0px; text-transform:none; word-spacing:0px;'>King County data are made available with the understanding that they shall be used exclusively by the obtainer or his/her authorized agents. Digital products may not be reproduced or redistributed in any form or by any means without the express written authorization of King County.King County, Puget Sound Stream Benthos Project e5e8ab3d7d93427cb3a37b810d733479 https://services.arcgis.com/Ej0PsM5Aw677QF1W/arcgis/rest/services/NZMS_attribute_table_2026-07-29/FeatureServer Feature Service EPSG 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