Sunday, September 7, 2014

The Mojave River Beaver Continues

And that is the last bit of surface flow in the Mojave River after coming off Deep Creek before it goes underground. Does not look very good for a beaver? No riparian corridor but Lawrence of Arabia amounts of sand. Until the river does something miraculous and resurfaces about 8 miles downstream at Mojave Narrows Regional Park where a confluence of geology forces the water back up. And discovering this amazing desert oasis are beavers from the nearby San Bernardino mountains where several translocations took place last century.

And they seem to like the desert.

Victorville looks like a veritable haven for beavers smack dab right in the middle of one of the most well known deserts in the world.

Look at that big body of water, the whole pond is about 750 feet long!!

You can actually back up and see the swath of riparian green - largely created by the beavers - contrasted sharply against the desert from outer space!! Beaver can attenuate waning surface flows and even more substantially increase subsurface flows.

A little bit after Victorville the river submerges underground again and the river become a wide sandy wash as pictured below.

So pretty cool little desert population of beaver. In the areas with surface flows the beaver have found them and greatly augmented the habitat for plants and wildlife, and deepened and widened the channel for more persistent year round flows and groundwater percolation. The Mojave River is a noted habitat for several endangered reptiles and amphibians - especially western pond turtles - and doubtless multitudes of bird species. Unfortunately the lone native fish - The Mojave Tui Chub - has more or less been pushed to the brink of extinction by its non - native introduced relative the Arroyo Chub. Interestingly the Mojave Tui Chub is an ice age holdover from when the Mojave river used to flow into a permanent lake so beaver would have likely benefited this fish as they prefer slow moving, lentic waters.


Friday, September 5, 2014

Why Are Rivers In Northern California Starting to Look Like Rivers In Southern California?

Ah the old southern vs northern Californian debate.... a little background from where I am coming from I have family in the Bay Area dating to the gold rush and even though I currently live in southern California and was born and raised here - I did go to school and live in northern California from 1997 to 2010. So bottom line is I feel first and foremost that I am Californian. Now you can inject any arguments and historical anecdotes that vilify southern California in terms of water usage - and truth be told southern California is and continues to be negligent both in terms of public and governmental use of water. But when it comes to bad, outdated policy and the loss of perennial flows and natural habitat both the North and South have blood on their hands. Remember for every Owens Valley there is also a Hetch Hetchy Valley.

Hetch Hetchy Valley- the "other" Yosemite, now a reservoir for Bay Area
I want to direct your attention to a YouTube clip The Eel River Has Stopped Flowing:

Now down here in socal we are used to seeing our rivers look like this, in fact this is more water than one should expect in a southern river by this time of the year. However the Eel River is not supposed to look like this. By the way it is named the Eel River for the historical abundance of lamprey that were found here - which are not true eels.

Let us see.... is there any other bad news I can throw at you? There has been the suggestion that the drought we are experiencing in California and the west may in fact be the start of a prolonged multi-decade drought or that even these rainfall patterns are the new normal. Cry me a (drying) river...

Northern and Southern California needs to get some common sense groundwater management, get rid of all the lawns, stop growing rice and nut crops, and start importing non-native beavers from Patagonia and Argentina to restore groundwater in ALL watersheds!!! Every problem is a chance for a creative solution!!!

Tuesday, August 19, 2014

England Looks In No Way Like Southern California

"You know what's remarkable is how much England looks in no way like Southern California."

Above is one of my favorite lines from Austin Powers 2: The Spy Who Shagged Me. If you need a refresher Austin is cruising the "English countryside" with Felicity Shagwell when he makes the comment. The irony of course, being that the scene and the whole movie were filmed in southern California.

Now taken as it is we have a great example of Michael Myers penchant for witty, off the cuff dialogue - the line was not scripted - and Heather Graham simply mutters "What?" in reply. But such a line, innocuous as it is, can take on some deeper meaning. For starters the native chaparral vegetation which dominates the coastal hillside of southern California and central California, along with oak savanna and coastal sage-scrub, is often featured in movies not explicitly taking place in California but filmed there due to the proximity of the film industry. Indeed the famous Hollywood sign is on a hillside of chaparral vegetation. In stands of old growth manzanita the tangle can get over 30 feet tall and by all accounts chaparral was actually some of the most productive grizzly habitat in the state. While it is true fire is part of this habitat, it has become apparent that the frequency of fire due to anthropogenic causes has increased over time to the detriment of the ecosystem. Interestingly the fire barriers created by people seeking to separate the brush from their property might be accelerating fire risk due to non-native grasses moving in and spreading fires.

Sespe Wilderness. Ventura backcountry
With its ubiquity in many of the most iconic spots in California and its export around the world via the film industry you might think native Californians would take pride in this unique biome found in only a few places on the planet. Unfortunately nothing could be further from the truth.

For the most part large swaths of the population look at chaparral as a prickly, dry, combustible, menace.  Fortunately there are lovers of chaparral - a notable example being the chaparral institute - which I encourage you to check out.

Old Growth Manzanita. San Luis Obispo county
It is for shame that California does not herald the unique chaparral biome to the extent it is does the redwood forest - or other parts of the country celebrate their native flora. I mean just check out how cool the twisted, gnarled bark of old growth manzanita looks. Now imagine all of coastal southern and central mountains dominated by stands of old growth manzanita. And this tall canopy creating shade and thermal refuge for amphibians, fungi, wildflowers, reptiles and mosses that one would not expect in such an arid climate. Grizzly bears carving out intricate mazes and centuries old foot paths through the tangle of growth.

Now to get back to what I was saying about Californians having at best an ambivalent relationship with chaparral and much of the native vegetation. This became especially obvious to me working at a retail plant nursery in the Bay Area. I would try and chide and cajole customers to the native plant section but  often time with frustrating results. People from the east coast wanted eastern Lilacs not ceanothus. Everyone insists on a lawn and water hungry annuals. About right here you can insert a discussion on planting for a drought tolerant landscape - especially in, you know, a time of drought.

Now let me dovetail this discussion into the insights gleaned by Heidi Perryman and others concerning why and how often beaver are lethally trapped in California over the last 20 months.

From Martinez Beavers
As discussed already on Martinez Beavers - Dying For Information - over 36% of complaints stem from either agriculture  (20%) or to trees/landscaping (16%). Although dealing with beaver in agricultural situations can be tricky - live trapping and relocation should be the option - it is the high number of reports of damage to trees and landscaping which resulted in 41 kills that is most distressing. And this is because it is easily remedied by a simple wire mesh around the trunk or bad tasting paint - but no plastic por favor. Or, as I would like to see, simply letting the area in question go native to the willows, cottonwood, sycamore and other trees than can coppice, resprout, and reseed in the wetland provided. Check out this cute blog Georgia Backyard Nature and the authors love/hate story of beaver felling valued trees. You can see that several of the trees the author bemoaned the loss of due to beaver actually resprouted and several other trees reseeded in the habitat made by the beaver.

But this recalcitrance to just let things go back to what is there naturally - whether it be your cities creek side park or beaver pond adjacent to your landscaped property - really speaks to the ambivalent relationship Californians have with chaparral. It is our emblematic native vegetation. In the past it provided sanctuary for grizzly in daunting chaparral mazes and today it fuels massive fires that threaten urban sprawl. In the past grizzly was seen as a challenge and menace to be eliminated by California settlers. Today fire is seen as a threat to California that needs managing. Both fire and the grizzly are intimately linked with the chaparral.

Whether it be fire, grizzly, or beaver it seems we have a tendency to try and demonize, eliminate, trap, or suppress it as opposed to understand, value, and cohabitate with it.

Santa Monica Mountains near Pt Mugu. Camarillo Springs Fire

One piece of good news is that there were no depredations for beaver in southern California during this period!!

Tuesday, August 5, 2014

Southland Beaver at the Martinez Beaver Festival!!

Just got back from my norcal trip to Martinez to host a booth at the annual Martinez Beaver Festival. It was a blast and met loads of cool people and made some nice contacts. Martinez is such a cool and funky little east bay town - when I lived in the Bay area I never got a chance to see this town but I really liked the vibe of the town.

There were over 40 booths with topics ranging from native gardening to cougars. But I noticed a common theme of grass roots, volunteer driven protection of animals and natural places. We should expect and encourage such groups in the future as governmental agencies only do so much. And CDFW, like any monolithic bureaucracy, can not pivot quickly enough to address multifaceted and quickly emerging topics in California's human mediated ecology.

The crowd was great, never too many people and the people I got a chance to really talk to seemed genuinely intrigued by the strange and little known saga of beaver in California. I did not come across anyone adverse to what I want to do and most seemed on the same page with me as far as putting more beaver in California, especially southern California (but one person wryly added do not take our northern Californian beaver). There were a lot more adults than I expected and although there were a lot of kids they did not dominate and seemed especially interested in the science. I myself brought 10 skins of birds that utilize riparian/pond habitat, my mural, and loads of photographs of beaver ponds, google earth imagery. People were impressed that beaver lived in such arid climes as the Mojave River.

After the festival I got a chance to explore Alhambra Creek and hopefully check out the beavers. I had it on good word that they usually start coming out around 6:30 so I had some down time to photograph and hang out at the local tavern. I had long known of the tidal influence from the nearby delta on this creek but was impressed by how much of it there was.

Above is the secondary dam before high tide. At high tide this dam was completely submerged and the beaver do a little maintenance after every high tide cycle evidently. Me and several other beaver watchers hung around for the nightly beaver watch. I myself was dead set on seeing a beaver as I have never seen a live, wild beaver (hark hark insert beaver pun of your choice here) and I was promised that the Alhambra beavers are pretty people friendly. At about 6:30, like promised, things started happening. A ripple here, a splash here I watched from the bridge overlooking one of the most active bank burrows. And then I did some counter surveillance at the main dam. And finally there was a beaver in the water - just lazing along. Me and several others were treated to quite a show at the main dam as one fairly big beaver - the good for nothing uncle some people claimed - made several up close appearances. My photos are all out of focus and wacky but hey - whatevs.

I though it was really cool how the beaver utilized the rising tide to get to vegetation normally out of reach. They especially liked the black berry bushes!!

Anyways blogger is not letting me link to youtube videos but if you want to check out my videos go to my youtube channel at Duane Nash.

I also got some nice shots of a pond turtle.

Anyways had a blast, thanks Heidi, Cheryl and everyone else involved!!

Tuesday, July 29, 2014

Odds N' Ends

Ok so I have not posted for a while but that does not mean I don't have a lot of stuff that I want to talk about. So I am going to use this post as a catch all for a whole slew of stuff that could easily be 3 or 4 posts.

First things first I have realized I need help in getting southland beaver up to the next level. I work two jobs, have another blog (antediluvian salad) that I like to update at least once a week, as well as you know, just life... so I am asking for help. If jump starting a nonprofit centered around beaver advocacy, protection, and reintroduction in southern/central California strikes your fancy please contact me @ Or if you are just curious and want to brainstorm ideas that is fine as well. If you are good at organizing things/paperwork/bureaucracy those skills would be especially handy as they are not my strong suits.

I have been busy though prepping for the Martinez Beaver festival where I will have a booth. As you can see I have designed a new banner for the site, color pencils btw and it took several months (but relatively short sessions each time). I also have been sending emails concerning the prospects of beaver in California watersheds. I plastered various staff at the CA department of Fish and Wildlife; deer people, small game people, fish people, bird people, just about any department I could find got an email from yours truly. Below is a copy of what I wrote.

Hello my name is Duane Nash and I want to draw your attention to a recent paper published by the California Department of Fish and Wildlife titled The Historical Range of Beaver (Castor canadensis) in Coastal California: A Review of the Evidence by Lanman et. al. found online here
This thorough review of the distribution of beaver in California extends their accepted range to include coastal southern California, the Sierra, and all of Northern California. Evidence for beaver in southern California includes biological specimens (collected from Sespe River 1906), ethnographic evidence including native American place names, words for beaver, beaver artifacts and beaver ceremonial customs including Chumash, and historical accounts from European colonization. It is likely that much of the beaver population in California, especially southern California, was eradicated prior to the gold rush by fur trappers - especially through the use of steel traps.  

Reintroduction, protection, and expansion of existing beaver populations in southern California dating from translocations performed by the department of fish and game in the early 20th century offer a pragmatic tool to enhance watershed health. Beaver have been documented to raise local water tables through their damming, creating year round flows and pools in creeks that formerly went dry such as in Susie Creek, Nevada. The diversity and extent of riparian habitat that beaver provide create abundant habitat for riparian organisms as well as secondary benefits to all animals in arid climates due to more dependable and consistent water regimes. Notable endangered, threatened, and species of concern that beaver benefit in southern California watersheds include southern steelhead (beaver ponds creating ideal feeding habitats for young fish and refugia for oversummering ocean run adults), pacific lamprey, tidewater goby, unarmored three-spine stickleback, western pond turtle, red-legged frog, least bell’s vireo, and willow flycatcher. Additionally beaver habitat provides habitat for numerous other non-threatened but declining birds, fish, reptiles, amphibians and others. Finally the woody debris that beaver transport into a watershed kickstart detrital food chains ultimately creating more abundant invertebtrate communites which benefits species higher up on the food chain, including humans that eat fish.

Beaver benefits to humans include, besides the above mentioned restored natural habitats which serve as a cognitive restorative tool for humans, an ability to both replenish aquifers and buffer against floods. A series of beaver dams works as a veritable series of speed bumps on flowing water helping to slow and spread the sometimes torrential downpours in arid regions. Unlike human made dams, water diversions, and spreading grounds to recharge aquifers beavers perform the same function but allow ecological connectivity. Fish can pass through, around, or over dams during high flows. In especially high flows dams will blow out. Finally beaver offer added economic incentive by attracting nature lovers, fishers, and bird watchers to impoverished communities.

It is my hope that you consider beaver a useful, pragmatic, and necessary tool in watershed health for these and other reasons. I believe it would be most fortuitous and timely for your organization to team up with beaver and embrace the most important keystone species on the North American continent.

Duane Nash

 I think it covers the bases nicely, no? But for my efforts, I emailed over 50 members of CDFW and got '0' replies. A big nada. Zilch. Now I know people are busy and yada, yada how dare I consider publicly funded branches of the government to, you know, respond to the public. But come on now just maybe one reply? Anyways the web address to wildlife programs at CDFW is
and if a few souls out there happen to read this and send staff more emails about beaver in California well that would just make my day. Constant pressure, constantly applied. 

Also if you like my letter feel free to copy and post it if you feel inspired to start petitioning your local agencies about beaver.

On a positive note I did get a reply and a meeting from a local, very powerful environmental ally. Can't apply for funding yet as I don't have non-profit status but if I could get them as beaver allies it could prove very fruitful. Let's just say they are very opposed to man-made dams but not necessarily beaver made dams.

1 Billion Dollars for the L.A. River?!?

Maybe you did not know L.A. had a river, much less 1 billion dollars to help restore it. But never the less this might just happen.

Personally I have mixed feelings about this. Much of the river, as you probably know, is channelized. Plans include widening parts of the river and amending recreational corridors along the river. Although there is a claim to return it to its 'wild state' this is doubtful because historically the L.A. River meandered all over the floodplain and I doubt that the Staples Center is going to be relocated for a properly meandering river. But it is encouraging that there is some type of energy building up for watershed health. But I would much rather have seen the money go to the Santa Clara River which is unchannelized and still has some of its native fish, unlike the L.A. river which has no native fish left and plenty of invasives. Oh yeah, invasive species and beaver are a recurring theme here. The L.A. River has no beaver as well - can't blame the beaver for this one now can we? BTW the angeleno chumash had a word for beaver and wore beaver pelts. Would be nice if a little bit of that 1 billion was used for a beaver feasibility study in the L.A. river...

But it is still over all great that this appears to be happening and a lot of people worked long and hard for this river. Even if 80% of the flow is treated effluent.

Heres a nice video of it:

Beaver in the Huffington Post!!!!

This is a good article and very positive towards beaver - and rightly negative towards cattle. As usual Heidi Perryman beat me to the comments section - that lady is on it!! But this is big exposure for beaver and it roundly criticizes the horrible water policies out west, especially when it come to cattle. I actually wrote about the cowbow mythos a while back on my other blog antediluvian salad, cowboys and dinosaurs. Essentially, contrary to what cattle ranchers would like you to believe, cattle are not desert animals nor did much of the land cattle are put on in the west ever support native bison. Where do cattle do best? Riverine forests, just the habitat their wild progenitor the auroch preferred. Georgia and Alabama are actually superior cattle range than Nevada and Texas!!

The Drought Rages On: But Does the Average Californian Know or Care About Where Their Water Comes From?

500$ fine for wasting water in California, or end up like the guy below.

Yep it is pretty hot out there, and pretty dry. I recently went down to check on the closest beaver population to me at the Santa Ynez River in Santa Barbara county. Let's just say it was so dry that the cottonwoods and willows were shedding their leaves like it was October. Not good. I don't know what happened to the beavers in the stretch of the river I go to. Did they flee to local golf ponds? Move up or down river? Let's hope they have the ecological flexibility to find a safe haven as I did not see any fresh beaver sign in an area usually brimming with beaver sign and the only pool of water was a decrepit pool full of trapped bull frog tadpoles. Anyways kind of depressing but I believe in just laying the ugly truth out there...

Yes, that is the most janky duck blind ever... and completely bone dry in an area with usually some water.

Dried up cattails in a beaver pond. Beaver can help keep areas wetter, but if the faucet at Cachuma reservoir is completely shut off and local farmers aggressively pump out every last trickle of groundwater,,, not much left for the wildlife.

To the left along the bank are a series of beaver bank burrows. Did not see any recent activity. Where do they go?

This is the freshest beaver sign I saw, a chewed stump. Hard to gage when it was cut... maybe a couple of weeks?

If you want to see what this river looks like during a water release when it is full of water check out this post: Beaver Safari on the Santa Ynez River

Friday, July 11, 2014

Southern California's Santa Margarita River: Undammed by Man, But Not Beaver

One of the more astonishing things I come across when I talk to people about beaver in arid southern California is that not only have they never thought about beaver here - they are shocked to learn Castor canadensis is already here!! From just a few males and females translocated by some a very prescient California Department of Fish and Game (now wildlife) officers these founding beavers, perhaps even mating with remnant populations of beaver in southern California have created stable and increasing beaver populations in several watersheds in southern California as well as the rest of the state. Kate Lundquist of Occidental Arts and Ecology Center ( kindly furnished me with the below map as well as additional detailed listings of the several hundred beaver translocations that took place in the early to mid 20th century.

Of course one should take note of the now outdated "original range map of beaver" as interpreted by Grinnel. New date has come to light showing that the historical range of beaver in California is best reflected by the map below per the work of Lanman et. al. 2013.

Now for this post I want to focus on a little heralded population of southern beavers represented by the stippled red dots on the river second from the bottom on the coast of California. That little river, better described as a creek in all actuality, is the Santa Margarita River. It's only about 30 miles long and like all rivers in socal is best described as intermittent. Formed by the confluence of Temecula and Murrieta Creeks, there are several well known beaver dams at the confluence. Now I have actually never visted this river but with the magic of google maps one can easily enough find the dams, from outer space!!

Hopefully you can see where I have measured this pond at about 47 meters (152 feet). Pretty nice litle beaver pond. Now I only recently started spending significant time tracing river/stream courses looking for beaver ponds and it is very fun I must admit. In fact I would suggest doing so is the best teaching tool for looking from a landscape perspective at where, how, and to what extent beaver do their work. I highly suggest it!!

Look at this big pond above over 140 meters (462 feet long) !! This might actually be an old dam, you can see it is not too well maintained. Or it might be a naturally occurring pool but the vegetated downstream section makes me thing mud was piled up there at one point.

Here is a pic of a series of dams that stretches over 357 meters long, for us Americans that is over 1170 feet long!! That has got to be a good amount of water storage. In fact a series of step dams seems to be a common style of dam in these low water volume watersheds. As you can see it is in a bit of a valley bottom. This is what beavers like, they are looking for alluvial - that means sediment bottomed - valleys at relatively low gradients. Along the coast range in southern California such a style of river/creek bottom is rare, but present in all watersheds. Although socal has a lot of high gradient, rocky bottomed creeks - they eventually plateau out in either wide bottomed valleys or the coastal floodplain.

Above is another example of a beaver pond at over 264 meters (868 feet long) in a broad, alluvial valley. Remember, having that alluvium, i.e. mud, to play around with allows the emergent vegetation and the riparian layer to develop that beaver need. This is why bedrock bottomed creeks/slot canyons are not so great for beaver dams. Hard for the vegetation to get a toehold.

Look at the dams above. You can see that vegetation is filling in the ponds. Chances are if beaver were not along this stretch of the river it would be completely dry. But beaver activity, I suspect deepening of the pools by beaver allows year round refugia. And this is a common theme looking at beaver activity along southern California streams/rivers. Long stretches of no water, followed by a gradual increase of vegetation and some surface flows and then you start to see hints of beaver activity and them voila active beaver ponds. Did the beaver seek out the springs of water or did they over time create them? You get into a little bit of a chicken vs egg conundrum. I am reminded of the Chumash oral tradition

Timbrook (2007:180) relates
a Chumash story where “a willow stick that had been cut by a beaver was thought to have
the power to bring water. The Chumash would treat the stick with ‘ayip (a ritually powerful
substance made from alum) and then plant it in the ground to create a permanent spring of

Now that is a very powerful and eloquent parable for the beaver in southern California. In fact that story is more potent and powerful than just about anything I have came up with on this blog!!

Now the Santa Margarita has several good things going for it. Its in a relatively remote section bordering San Diego, Riverside, and Los Angeles counties and parts of it go through an ecological preserve of UC San Diego and Camp Pendleton both sites of which beaver are on. Military bases and environmental conservation make for strange bedfellows but you would be surprised. Also the Nature Conservancy has invested in the river. And no dams. Unfortunately non-native beasties have heavily infiltrated the system. And as is usually the case beaver - not humans as should logically be the conclusion - are posited as responsible for the spread of invasives. From a paper Status and Distribution of Fishes in the Santa Margarita River USGS May 2000 available online:

While the presence of beaver ponds to slow the water flow (thereby locally 
reducing the gradient) could be interpreted as favorable to stickleback, this would only be 
the case if the exotics were absent.  In addition, the beaver dams cause increased water 
temperatures that would be detrimental to the stickleback.  Threespine stickleback have 
thermal requirements higher that rainbow trout but lower than arroyo chub (Swift 1989) 
and would do better in the cooler flowing waters of the natural stream.  Stickleback were 
undoubtedly numerous in the large slowly flowing, algae filled pools in the gorge before 
the advent of exotic species.  In any case the necessity to limit or exclude beaver ponds as 
favoring exotic predatory exotic species overrides any consideration of possibly 
increasing habitat for stickleback that do now currently inhabit the drainage. 

Now they only assert the beaver ponds are raising water temperatures - they actually do not measure them. How the ponds affect water temperature depends on how much hyporheic exchange is going on - as well as how deep the pond is.

three-spined stickleback

Of the four originally native species to the river steelhead, pacific lamprey, arroyo chub, and threespine stickleback only arroyo chub was found in their survey. Interestingly striped mullet, an estuarine fish, went pretty far upriver. And as you can see from the list of exotics, it is  a system dominated by them. How are we to say with or without beaver that the natives would not be in trouble? I mean this is the situation on the Santa Clara River where there are no beaver but plenty of non-natives.

Nope I consider blaming beaver for the spread of invasives a bit of a logical fallacy - if you want to blame something blame humans - we put them there.

A big dilemma with non-natives and something that I think should be iterated is that many of the species in question are from the east coast of America. So beaver dams are not anything new to the ecology of these species. Furthermore if you are a green sunfish or a largemouth bass you do not really care if you are in a beaver pond, an irrigation ditch, or an oxbow - you found a good home. And secondly these east coast fish evolved in more competitive, diverse assemblages of fish than western species. So when push comes to shove they are just a bit more pugnacious, aggressive, and voracious than native fish. Holds true for bullfrogs and Louisiana swamp crawfish.

Fishing for Beaver Pond Bass - it's a thing

In fact in the case of bass there is a little bit of fisherman's cult emerging concerning bass and beaver ponds. Turns out, surprise surprise, the prized game fish just loves to hole up in beaver ponds and especially likes all the woody debris in the dam to hide out in during the day.

The way I see it the issue of invasives in California/arid watersheds is as such:

1) Do nothing. Admit they are too widespread and numerous to control. The new fish fauna is an alien fish fauna and this is the new normal. This is what seems to be happening anyways and is pretty much the default solution based on what I have seen. All those man made dams and reservoirs are stocked with non-native species for fishing purposes. Whenever there is a flood or water release the downstream river from the reservoir is inoculated with non-natives.

2) Do everything. Massive campaigns of eradication including hand capture, fishing, electroshock netting to eradicate non-natives. Several complete sweeps of entire watersheds necessary. Stringent laws enacted to penalize intentional release of non-natives. Somehow eradicate founding populations of non-natives from lakes and reservoirs. Likelihood virtually nil considering the scope, magnitude and prices involved. Would require a seismic shift in societal attitude.

3) Mitigation. Find ways for natives and non-natives to coexist. Electroshock areas and clean out non-natives but leave natives. Encourage restoration of native predatory birds, mammals, and reptiles to hold non-natives in check. Probably the best and most practical option for maintaining native populations.

As I have discussed before beaver ponds can be utilized as a tool for trapping out non-natives. If we know such and such non-native species is utilizing beaver ponds preferentially that species can be targeted at beaver ponds. Hand capture, netting, electroshock can be utilized to clean out the unwanted but leave in the wanted. Encourage the return of native predators to hold aliens species at check. Beaver ponds are easily found via google maps and can thus be cleaned occasionally of non-natives.