Why are New Zealand Mudsnails a Problem?
- They’re tiny! Adults are about the size of a grain of rice and immature snails are even smaller.
- They’re clingy! Because they’re so small, they can sneak aboard almost anything including waders, boots, floaties, and even between the pads of a dog’s foot. If it can carry a sand grain, it can carry a mudsnail.
- They’re hardy! Mudsnails can survive out of water for days.
- It only takes one! Mudsnails reproduce asexually (i.e. cloning) so a single mudsnail can result in a colony of 40 million snails in just one year.
- They’re tenacious! Once they establish in a creek, it’s practically impossible to get rid of them.
- They’re bad news! New Zealand mudsnails can achieve densities of over 70,000 snails per square foot. They displace native aquatic insects, which fish eat, and pass through fish digestive systems without being digested. Ultimately this can result in reduced growth rates and lower populations of fish.
Help Prevent the Spread of Mudsnails
The city reminds residents – particularly anglers and dog guardians – to help protect sensitive natural areas by not accessing closure areas. If visitors or anglers access open creek areas, they should remember to:
- Brush dog paws and bellies carefully on dry land.
- Use a wire brush to remove mud and vegetation from their boots and gear immediately after stepping back onto dry ground.
- Take precautionary steps detailed by Colorado Parks and Wildlife (CPW) when they are back home or before they go to another body of water. Those measures include freezing boots and gear overnight, soaking equipment in hot water, submerging waders and other equipment in solution specified by CPW, or drying boots and gear – preferably in direct sunlight – for at least 48 hours.
- Not flush water used to clean boots or rinse equipment down storm drains.
Closures to Limit Their Spread
- Year-round: Dry Creek
- Year-round: Boulder Creek downstream of Valmont Road
- Year-Round: South Boulder Creek area near the South Mesa Trailhead
- Temporary: South Boulder Creek from South Boulder Road to Marshall Road