2005 New HUC Reports

From early 2005 to early 2006, New Zealand mudsnails were reported in 8 new western HUCs (cataloging units). This is not always based on new data, only on new reports to the database here. Note: the Little Bighorn cataloging unit in Montana is not positive. It was temporarily indicated as positive due to bum location data in the database. Of the 8 new HUCs, only 2 could be natural range expansion. Two of the new HUCs appear to represent large jumps by the snails, likely with human assistance. The 4 remaining HUCs are smaller jumps and 3 of these are coastal rivers. Click on the map for a larger version. The new HUCs include:

1. The Upper Missouri-Dearborn (Montana): The snails moved downstream in the Missouri River, but they have still not developed large populations here.
2. Bruneau (Idaho): The snails moved upstream from the Snake River, but only a short distance and in small numbers.
3. Lower Deschutes (Oregon): The snails jumped a fair distance to get into this central Oregon tailwater river. Populations were low when first discovered.
4. Umpqua (Oregon): The snails jumped into another coastal river. The population is already very large here.
5. Coos (Oregon): The snails jumped into another coastal river. They are already abundant here and occur in the intertidal zone of the river.
6. Lower Rogue (Oregon): The snails jumped into yet another coastal river. This population was known for several years before getting into the database here. The snails can be abundant here.
7. Mono Lake (California): The snails jumped a short distance (at least) into the lake headwaters. The population is at least moderate when discovered.
8. Santa Clara (California): The snails made a large jump into this southern California tailwater river. The population was small when first discovered.