so sea walls let's keep talking about them here's stone steps right if you go down to stone steps and you walk north you're going to see a variety of sea walls right here here's one sea wall believe it or not there's an owner of a house that lives up here and they built a staircase through all these trees comes through here it's got a nice deck and then the staircase goes down behind this wall and this door opens from top down and has like a ladder that they walk down right so obviously they got a ton of money it's something that they got a chance to build it i mean it's it's an amazing fortress if you will but what it's causing is extra erosion of the beach right really quick side question for you is this a wintertime beach or is it a summertime beach can you tell yup this is a wintertime beach because look at all the cobbles on the beach right this would be all sand in the summer but it's all cobbles in the winter this is a wintertime beach another side topic where is this water coming from where is that water coming from that's right all that water is coming from this homeowner watering their garden watering all their plants that probably aren't native to this area therefore they need a ton of water and it's making its way through the ground it's also water from yep you guessed it leaky pipes right water pipes sewage pipes all sorts of pipes leaky pipes now that groundwater comes down and it gets released right here right into the ocean which i get to go swim and surf in yay right you get to too no it's not that cool right it's not very cool so um back to sea walls let's get back into it sorry i ranted there for a moment but um if you look here's a spot without a sea wall right check out the notch that it creates at the base and this cliff is going to collapse here's a sea wall they built um and it has a different look to it right it's smaller and it's more natural looking than this right i mean this looks like we're ready for war this looks like oh they just built like a stabilization thing and it's got a funny kind of texture to it looks almost like the cliff i'm going to tell you that in 1994 the california coastal commission mandated that anything built sea wall style after 1994 had to look more naturalistic like the cliff so this has been built after 1994. this was built pre-1994 now you know when things were built if you go see a sea wall and it doesn't look very naturalistic with this texture on it then you know that it was built before 1994. now because of the fact that all that sand now is uh it's gone right it's gone from uh the rivers because that used to be 90 percent right of where our our our beach was coming from what we have to do is we have to dredge sand right it's a very expensive process in which we take boats that go out to submarine canyons we talked about those right that's where all our sand ends up in the beach compartment that's step number three we dredge that back up and then bring it all the way back to shore and pump it right onto the beach does that cost a lot of money you're darn right it costs a lot of money okay so sources of sand well it'd be nice if we could remove the dams uh it'd be nice if we dredged nearby sources um and it'd be nice if we restored the wetlands so i'm gonna have you watch this video right it's called putting more sand on carlsbad's carl's bad speeches i uh i want you to watch it and think critically about it and we're going to discuss this video afterwards okay you know now this is what i want to to to hit you with okay you know now that the rivers have been damned so we don't get sand from that anymore you also know that the homeowners are building sea walls which increases the rate at which beaches get eroded away uh you didn't know this yet but there was a study done at ucsd down at scripps institution of oceanography by a professor i know driscoll and hoss actually and what they found is that the amount of sand that we have on our beaches naturally comes a lot from cliff erosion right so clip erosion actually adds up to about 50 percent of the sand that we have on our beaches so if we go back this erosion of this cliff all this every day slowly but surely eroding away you go down there you can you can watch it's starting to erode away 50 percent of our sand comes from cliff erosion the way they did this is they looked at the mineralogy of the sand and what they found is that the quartz grains that originate in the cliff they they call those they're clear okay and the and the quartz grains that come from dredge sand or from rivers are frosted meaning they're all scratched up so they can actually figure out the sources and if you look at sand on the beach you could actually determine the percentage of quartz grains that are clear or frosted and therefore they figured out fifty percent of the sand comes from cliff erosion but guess what happens when you build a sea wall like this you don't get any more sand from the cliff erosion so effectively we've got no more sand from the rivers no more sand from cliff erosion all we have is sand replenishment from dredging okay and that costs a lot of money so let's take a look at this video and we'll go from there right take a look [Music] the city of carlsbad is doing its part to make sure there's plenty of sand on local beaches my name is steve janz with the city of carlsbad did you know that the beaches are not owned by the city but are owned and managed by the california parks and recreation department and to keep the beaches healthy and full of clean sand the city and the state worked together with local agencies to replenish the sand from three different partnership projects changes in the natural environment have reduced the amount of sand that makes it to our beaches the beaches also lose sand during winter storms when waves carry much of the sand back out to the ocean floor that means we need to add more sand to our beaches to keep them from eroding here's how we work with local agencies to make sure our beaches are full of sand [Music] we are part of a regional effort to bring sand to our beach the san diego association of governments known as sandag works with coastal cities and other agencies to develop and pay for this important regional project a large dredge vessel collects the sand from underwater valleys and then pumps that sand onto the local beaches about every two years the western basin of the agua hadiana lagoon is dredged by the power plant a dredge vessel collects the sand from the mouth of the lagoon which then pumps the sand onto the beach keeping the mouth of the lagoon clear of sand allows more water to reach the encina power station which uses sea water to cool their large gas-fired boilers this project could bring up to a half a million cubic yards of sand to carlsbad beaches [Music] and the bataquetas lagoon is also dredged every few years as needed to ensure the lagoon is healthy for fish and wildlife and this provides sand to the south carlsbad beaches the process includes dredging the bottom of the lagoon to keep it deep enough to allow the tides to keep the lagoon free from silt another benefit of the dredging is that it improves natural nesting areas for many endangered birds and fish species the city of carlsbad works on this project with the california department of fish and game which pays for this project so the next time you visit carlsbad beaches you'll know the sand is there in part because of mother nature and in part because the strong partnership between the city of carlsbad and other agencies to learn more about carlsbad beaches check the city's website thanks for watching