El Dorado Nature Center Stream Restoration Project

Construction is Done

2010-02-25T15:17:00.000-08:00

This week was spent driving willow stakes in strategic locations, cleaning up, and moving out. The photo above shows willow stakes planted through the coir fabric on the bank next to the 5th bridge. These stakes will sprout and provide both screening and bank stabilization. We weren't able to plant nearly as many of these as we would have liked. But we were able to get them into certain key spots, like adjacent to the bridges and the boulder bank treatments. The photo below shows the construction foreman loading up creosote-treated logs, some of the last of the construction debris.

Before the contractor left, all areas impacted by construction were restored to their pre-construction state. The photo above shows one of Bubalo's crew hand-finishing an area that had been used for heavy equipment access.

The photo below shows the 3rd bridge. The construction is complete, but the restoration is not. Nature Center staff and volunteers have started planting native plants along the stream. Between the construction, the planting, and time, the project team is confident that we are creating a healthy riparian corridor. Birds and fish have already started returning to the stream and the trails will be open to the public starting next week.

Opening Up the Weir

2010-02-22T16:33:00.000-08:00

A small crowd of Habitat Stewards and Nature Center staff began to gather at about 1 this afternoon to watch the dam being removed at the north lake.

Using a combination of heavy equipment and hand labor, the sandbag dam that had been keeping the north lake from flowing into the stream was removed.

The dam at the south lake had already been removed and the fall is so short between the two lakes that the stream had backed up all the way to the dam at the north lake. This made the breaching of the weir rather anticlimactic, but it was still terrific to hear the water babbling over the weir again.

Once the dam was removed, the contractor finished the boulder treatment of the west bank, placing a large boulder in the place where the dam had been. The crowd of onlookers was very impressed by the contractor's teamwork and delicate touch with the back hoe.

This is what the weir and the 1st bridge look like now. In case you don't remember or didn't ever see it, below is what the weir looked like at the start of this project. The first photo is looking downstream from the 1st bridge, the second photo is looking east across the weir.

Bioengineering

2010-02-19T11:10:00.000-08:00

One of the last pieces of the stream restoration is protecting the banks from future erosion. Due to the severely limited project budget, only the bare minimum of bioengineering techniques are being used. These photos show coir blankets being installed on the banks. Coir is a very strong and flexible mesh made of coconut fibers. It is being attached to the banks using wooden stakes and biodegradable staples (made from corn). Plants will be planted directly through the blanket and the coir will hold the banks until the plants grow large enough so that their roots can form a strong protective matrix. Coir installation is labor intensive, and the Conservation Corps of Long Beach (in the blue shirts) was brought in to assist. This provided good work experience for the Corps members and saved a little money for the project.

Coir blankets were installed along the full length of the stream (except at the boulder treatments and bridges). Unfortunately, the project budget can only afford to pay for Bubalo to plant willow stakes at key locations. Over the next few months, Nature Center staff and volunteers will be planting container plants and more willows to provide additional bank protection, riparian habitat, and visual screening.

Some EDNC regulars just can't wait

2010-02-16T14:26:00.000-08:00

This pair of ducks was enjoying the area just upstream of the 3rd bridge this morning.

Apparently, they decided to head north.

Good thinking (for a duck), as the stream was about to disappear...again.

Off they went towards the north lake.

They'll be able to swim all the way from one lake to the other soon -- just not quite yet.

The bridges are in.

2010-02-12T09:15:00.000-08:00

The bridges have all been installed and the trails approaching them have been regraded to provide smooth transitions. In some places, ramps were constructed to bring the level of the trail up to the level of the bridge. Boulders were placed on the sides of the ramps to provide stability and aesthetic appeal. The photo below shows the 1st bridge, where the stream flows out of the north lake.

In addition to creating a smooth transition between bridge and trail, the areas around the bridges were graded to direct runoff from the trails into vegetation, rather than having water flow onto the bridges or straight down the stream banks. This helps prevent erosion and creates a more pleasant walking experience in wet weather. The photo below shows bridge 2.

Below is bridge 3. In front of the bridge is a roll of coir fabric that will be unrolled and tacked to the bank next week. Behind the bridge, you can see the alder that was felled earlier in the week. You can see how close this alder is to the bridge and what a hazard it was to have a large standing dead tree so close to the trail and bridge.

The photo below shows the 4th bridge, near the junction of the 1-mile and the 2-mile trails. The point bar, which is not quite finished, can be seen in the background.

Here is the 5th bridge. The high water mark on the banks is a dramatic illustration of just how much water was in the stream from the recent storms.

Residents and visitors to the Nature Center began using the bridges as soon as they were installed, as evidenced by these prints on the 4th bridge. I assume the boot print is from one of the construction workers. This bridge was installed last Friday (2/5) and this photo was taken on Monday (2/8).

T..I..M..B..E..R..!..!..!

2010-02-08T15:48:00.000-08:00

The bridge abutments are finished and the bridges are being installed. The photo above shows where the 3rd bridge will be (the bridge itself is sort of visible on the west bank). Just at the bend in the stream, you can see a large double-trunked alder. What you can't see in this photo is that the tree is tall, dead, and rotting. The project team was concerned that it could fall on the brand new bridge, something that would be both dangerous and expensive. So we decided to take it down and make it a feature instead of a liability.

The contractor first dug a large hole behind the tree so the root ball could come out more easily.

Then the contractor just pushed the tree over. This was not as simple as it looks -- it takes skill to aim a tree trunk with a back hoe.

After a bit of pushing, digging, repositioning, and pushing some more, the tree finally came down.

There is a good amount of water in the stream from last week's rains and the tree made a tremendous splash when it fell.

The tree fell exactly where the project team wanted it. To eliminate the temptation to cross the stream on this ad hoc bridge, the branches and upper trunks will be cut and hauled up into the blackberry thicket on the far side of the stream. The root wad and lower trunks will stay pretty much where they are, creating an interesting little spot in the stream. This is right next to Bridge 3, so visitors will have an excellent view of it once the trail is reopened. Be sure to look for it when you're here.

Bridges!

2010-02-05T10:50:00.000-08:00

The streambed was dry enough this week to backfill around all the bridge abutments and do almost all of the finish grading.

Many of the bridge approaches had eroded so severely that the trails approaching the bridges had to be raised a foot or more. The photo below shows the upstream approach to the 3rd bridge, an area that was chronically muddy and where the trail was crumbling into the stream. The regraded trail looks perfectly normal in this view.

But look at that same stretch of trail viewed from just downstream of the bridge in the photo below. Notice the trail marker and bench next to the bridge abutment--the bench is now below the level of the finish grade. Obviously, the bench will be removed and the area filled to bring the grade up to match the surroundings.

The biggest excitement this week was the arrival of the bridges from Alabama. They arrived very early Thursday morning and were off-loaded to the staging area near the utility towers.

The photo below shows the 5th bridge (the one closest to the south lake) being placed. Once the exact location for the bridge was determined, the contractor marked the places to drill and began the process of bolting the bridge to the abutment and making sure it was level. By the time rain stopped work on Friday, the 5th and the 4th bridges were done.

Apres le Deluge

2010-01-29T11:16:00.000-08:00

We have indeed been deluged by rain the last couple of weeks and it may not be over yet. The National Weather Service is saying we will have an El Nino February, meaning higher than normal rainfall. We need the rain, but it delays our project and increases our costs. Oh, well, water under the bridge, as they say.

On the up side, the dangerously low level of the south lake has been taken care of. Bubalo let water flow into the south lake until it was quite full, then closed up the dam again and pumped the remaining water in the streambed off to the sides of the stream.

As this photo of the dam at the south lake shows, some parts of the stream bank experienced pretty severe erosion. The project team walked the full length of the stream on Thursday to identify erosion and to make sure that those areas are properly addressed as we strengthen the banks over the next couple of weeks.

We also lost some trees in the storms. Above is the large alder that we refer to as the "bee tree." You can just see a brown bat box attached to the trunk closest to the ground (just to the right of where the upper tree crosses over the lower tree). Someone put that bat box up for bats (obviously), but the bees had a different idea. They soon took it over and it has been a bee hive for quite a while. There are so many bees around it that no one is going to remove that bat box. We'll see if the bees abandon it now that it has a new ground-level location. Cuttings from this alder will be used to help strengthen the stream bank where it fell and we expect a small alder grove to grow there in time.

Most of the work this week has been pumping water out of the stream, but Bubalo was also able to do some boulder work at the weir. The boulders being placed in the bank will provide a strong and level surface, allowing visitors to get right up to the edge of the stream without damaging the bank and causing erosion. The weir is also being reworked to allow more flow and to be more aesthetically pleasing.

Wildlife

2010-01-29T09:34:00.000-08:00

Thursday, 1/28, was a beautiful day in Southern California. Apparantly the blue skies and fresh air attracted a lot of wildlife, including some birds that we don't often see at the Nature Center. Here is a Green Heron enjoying the sun.

Below is a Double Crested Cormorant scanning the water for a morning snack. Just after the photo was taken, this cormorant snapped up a fish that looked to be about 4" long.

This juvenile Least Bittern didn't seem bothered by the heavy equipment moving boulders on the streambank about 30 feet away. The sun and the wealth of pollywogs in the water more than made up for the noise.

The Nature Center turtles have been hibernating in the mud around the lakes for the past couple of months and the warmer weather brought them out in droves. Dozens of turtles were floating happily in the lakes, with just their faces above the water, soaking up sun and air. Below is a River Cooter showing off the pretty yellow markings under his/her chin.

Fungus are sort of the bridge between flora and fauna and, of course, the rains have been great for the fungus population. Below is a photo that I really like, showing a very clear image of gills.

Rain of Epic Proportions

2010-01-22T10:26:00.000-08:00

Willow poles will be planted along the stream banks to prevent erosion. The half-mile long stream has a mile of banks and that means we need a lot of willow cuttings. Willows grow literally like weeds and need to be removed from waterways that serve as flood control channels. Mike Bubalo Construction has another project constructing spreading basins for the Santa Ana River, and the site is thick with willows. So they are removing willows from there and bringing them to the Nature Center to use in our bioengineering treatments. It's really a win-win situation.

Looking at the pond built to hold the willows last week, we wondered how we would keep it from drying out.

Dry willows turned out to be the least of our concerns this week as torrential rains drenched Southern California. The lakes in El Dorado Regional Park are connected, with overflow from the first lake south of Carson flowing to the lake north of Wardlow, then under Wardlow to the lake south of Wardlow, then to Horseshoe Lake, finally flowing into the north lake at the Nature Center. The photo above shows the overflowing Horseshoe Lake just north of Spring Street in the Regional Park. The photo below shows the overflow draining towards the culvert under Spring Street, on its way to the Nature Center.

The north lake quickly overtopped the dam above the weir and water flowed into the streambed. The dam at the south lake was intentionally breached to allow storm water to drain from the stream and into the south lake. Overflow from the south lake drains into Coyote Creek and then into the San Gabriel River and on to the Pacific Ocean.

While the rains will delay the project a little bit, they also give us the opportunity to check where bank erosion is the most severe. Next week we'll be making sure that our bank treatments are focused on the places that most need protection.

3 Abutments Down, 2 to Go

2010-01-15T09:30:00.000-08:00

The foundations for the bridge abutments were poured last Friday (1/8). Above is a photo of the foundation for the east abutment for Bridge 2. On Wednesday, 1/13, the abutments were poured for Bridges 1, 3, and 4. The abutments for Bridges 2 and 5 are scheduled for later this morning. The photo below shows the pour of the west abutment for Bridge 3.

After the concrete is poured and vibrated, it has to be smoothed and finished. This work looks really easy, but the material is heavy and it takes a skilled hand and eye to do a good job quickly.

Once the concrete has set enough, the forms are removed. In about 2 weeks, the concrete will be fully set. The pre-fabricated bridges will arrive and will be placed atop these abutments. The area around the abutment will be back-filled and boulders will be placed aesthetically around the abutment and streambank for erosion protection. The path will be graded to provide a smooth transition between path and bridge. Above is the east abutment for Bridge 1. I thought it looked like an upright piano, so I gathered up wood chips for the black keys and asked Terry to play us a little tune. The sound from this thing is awful, but how often do you get to play a concrete piano while standing in a dry streambed?

Pouring the Foundations

2010-01-12T09:33:00.000-08:00

On Friday, 1/8, the foundations for the bridge abutments were poured. Access to the location of the 1st bridge was the most difficult and concrete had to be brought in with a skip loader. But even the skip loader could only get to the abutment on the east side of the stream.

Access is so limited on the west side that the only thing small enough is a Bobcat. The Bobcat scooped concrete from the skip loader and took it to the other side of the streambed. Doesn't it look like a baby bird being fed by its mommy or daddy?

And here is the Bobcat putting concrete into the form for the west abutment for the 1st pedestrian bridge.

The other bridges are MUCH more accessible, and the cement mixer was able to drive down the stream corridor and pour straight into the forms. The photo above shows concrete being poured into the form for the east abutment for bridge #5. The crew member on the right is vibrating the concrete so it will fill the form evenly and bond strongly to the rebar. The photo below shows the mason getting the concrete smooth and level.

Getting Ready to Pour

2010-01-08T09:24:00.000-08:00

The pits have been dug and the rebar placed for the footings for all the bridge abutments. The inspector from the City's Department of Development Services was out on Thursday to check it all out, and the concrete is scheduled to be poured later today. The photos above are at the location of the 1st pedestrian bridge -- where the stream flows out of the north lake and over the weir.

The 2 photos above show the locations of the 2nd and 4th bridges. You can see the rebar sticking up out of the holes, ready for concrete to be poured around it. The bridges are being manufactured in Alabama and trucked to Long Beach ready to be secured to the abutments. The only bridge construction that has to be done on-site is attaching the hand rails. The weathering steel of the bridges will add a beautiful rustic flair, while proving secure crossings and clear views of the stream--a big improvement over the crumbling, slippery, and wobbly original bridges.

The Hard Stuff

2009-12-30T14:32:00.000-08:00

The bridges are being manufactured and the poured-in-place concrete abutments for the 5 new bridges have been approved by the City. The longer the concrete allowed to sit, the stronger the abutment will be. So the contractor is taking advantage of the holiday lull to get ready to pour concrete. The photo above shows crew members marking out where the abutments will go.

The point bar is starting to take shape as cobbles are brought in and placed.

There are a few places along the stream where we want to let visitors get right up to the water, but we also need to provide some extra-strong protection for the bank. In those places, the contractor has placed large, angular boulders that lock together to form a solid structure. There is no grout or concrete holding the boulders together, just gravity and friction--two things that will outlast the strongest grout.

Bioengineering 101

2009-12-22T09:23:00.000-08:00

On Friday (12/18/09), Drew Goetting, Principal designer at Restoration Design Group, came down from Berkeley to give us all a lesson in bioengineering. First, dig a 3-4" deep trench at the toe of the bank slope. Toss the dirt from the trench upslope to make it easier to fill the wattle.

Next, lay out the coir fabric so the edge extends a few inches upslope past the lip of the trench. Secure the fabric to the soil with biodegradable staples (in this case, Bio-Stakes made from corn).

Shovel some of the soil from the trench over the coir fabric, then place willow pieces (branches, twigs, and leaves) over the soil. Add more willows and more soil, making sure that the willows are generally oriented along the streambank and no branches are sticking out perpendicular to the direction of the water flow. More willows and more soil, until the whole thing is the right height (see below for what "right" means).

Next, imagine that you are making a giant California roll, using the coir fabric as your sushi mat and the willows and dirt as your rice, crab (or krab), and avocado. Kick and push the mixture into place--it is pretty rugged and will withstand some rough treatment. The goal is an evenly compacted roll whose top is fairly level. The finished top of the willow wattle should be above the water surface when the stream is flowing.

Pull the coir fabric fairly tightly over the soil and willows. Secure the edge of the coir fabric with more biodegradable staples.

Pound some willow stakes straight through the entire thing. The stakes should go at least a couple of feet into the ground under the wattle.

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The result is a willow wattle. The fabric will hold the soil and protect the bank on a temporary basis. Meanwhile, some of the willows inside the wattle and some of the willow stakes will sprout and their roots will grow to hold the streambank. After a while, the coir fabric and the staples will biodegrade and all that will be left will be willows, creating a sustainable streambank and a vegetative screen of riparian habitat.

Fine Grading

2009-12-17T15:37:00.000-08:00

About half of the stream has dried out enough so that heavy equipment can go back in. The contractor is doing the fine grading, getting the elevation of the streambed just right and contouring the banks so they are ready for installation of the bioengineering bank strengthening. The contractor has also installed a couple of areas of boulder reinforcement like what is shown in the photo above. The stream restoration consultants will come in tomorrow to look at this boulder reinforcement to make sure it is properly done. Once the restoration consultant is satisfied with the contractor's work, this bank treatment will be replicated at a few more locations along the stream. The boulder treatment is being used at spots where erosion potential is greatest--immediately upstream and downstream of the pedestrian bridges, and at a couple of places where the walking trail comes very close to the stream. The restoration consultant will also be giving the contractor detailed instructions in planting willow poles and stakes, installing coir logs, and building willow wattles. Some of the willows will even be harvested from within the Nature Center itself.

And the rains came...

2009-12-14T16:16:00.000-08:00

The weekend rains put quite a bit of water into the streambed. The contractor's crew was wading through water and mud today pumping the water out. Once the water is gone, it will take another couple of days for the streambed to dry out enough to take equipment back in. Hopefully, we won't lose too many more days to rain.

In Spite of the Rain

2009-12-11T10:25:00.000-08:00

It's been a rainy week at the Nature Center, but work continues on the stream. Last week I posted a photo of the point bar cobble mock-up. You can see the mock-up in the center-right of this photo. This week the exact location for the cobbles was defined and graded. The cobbles will be about one foot deep, so the slope needs to be lowered by that amount to allow for a smooth transition between the surrounding grade and the cobbles.

The stream grading is almost finished, with just a small area upstream of the south lake remaining. When the muck was dredged out of the stream, the contractor spread it in an unused part of the Nature Center south of Willow Street. The material was turned periodically, enabling it to dry out. The contractor has used that dried out dredge material mixed with clean soil (yes, we tested it) to build up the streambed to the specifications on the plans. The photos below show the big pile of material that was taken out of the streambed in October (left) and what that pile looks like now (right). The woman with the muck in her hand is Jessica Hall from Restoration Design Group.

Mocking up the Point Bar

2009-12-08T10:04:00.000-08:00

The contractor mocked up a small section of cobbles so we could get an idea of how the point bar area will look. The area will use cobbles that are approximately 6" in diameter, with coarse sand spread between them for stability. The mock-up shown above used materials on hand rather than the materials we want in the final product, so is has road sub-base instead of sand. This worked well enough, but didn't look very good. Even with the larger sub-base material, the field of cobbles was quite stable. The area will be uneven to maintain a natural look, but will be fairly easy to walk on (though not for those in high heels or toddlers just learning to walk).

Field Design

2009-12-04T09:59:00.000-08:00

Because the exact condition of the stream could not be determined in advance, this project is being done as a design-build. The contractor is working from 30% construction plans with frequent input from the designers and City staff. Here, the project team is discussing when and how to remove willows that lean over the trail. These willows will be cut where the orange line has been painted across the trunk. The trunks, branches, and leaves will be used for staking and in willow wattles; the root ball will be used for further bank stabilization and to give the stream a more natural look.

Surveying

2009-12-01T11:07:00.000-08:00

The surveyors are out today, establishing the elevations for the stream from the north lake to the south lake. In concert with the stream restoration consultants, we will determine exactly how much to raise the elevation of the north lake. The decision will balance improving the stream flow with innundating the edges of the north lake.

Entwined No More

2009-12-01T10:56:00.000-08:00

On Nov. 5, I posted a photo of a sycamore and pepper tree twisted together and seemingly forming a single hybrid tree. Above is another "before" shot, and below is the same tree today. You can see a small bit of the pepper that was left attached to the sycamore -- to have removed that would have damaged the sycamore unnecessarily. The sycamore is kind of spindly and leggy right now, but it likely will fill out and regain a more healthy shape now that the pepper has been removed and the sycamore has access to light and air.

Dredging and Vegetation Removal Completed

2009-11-25T15:00:00.000-08:00

The stream has been dredged and non-native vegetation has been removed. A swath ranging from 10 feet wide to 40+ feet wide has been cleared on either side of the stream bed. This photo is looking downstream from a spot between the 5th bridge and the south lake. The next step is a detailed survey to establish the exact elevation of the stream channel at approximately 35 locations between the north and south lakes. This is a critical step as the flow of the stream depends on the elevation falling between the two lakes. Before this project began, the north lake was only 1 foot higher than the south lake. That meant that the stream only had 1 foot of fall over its entire half-mile length. This project includes replacing the weir where the stream comes out of the north lake. The new weir will raise the elevation of the north lake by approximately 1 foot, effectively doubling the amount of fall as the stream flows to the south lake.

Boulders

2009-11-25T14:43:00.000-08:00

Boulders will be placed in strategic locations to protect the stream banks from future erosion. The boulders have to lock together to effectively hold the bank. If they don't, the water will slowly edge the boulders away from each other, slowly gaining access to the soil behind, and eventually washing the soil away, leaving individual boulders where the bank used to be. Previous failed attempts at boulder treatment used rocks that were too round and so didn't lock together. Since we don't have a source for angular boulders, the contractor broke very large round boulders into smaller pieces. As this photo shows, the resulting pieces have lots of sharp edges--perfect for locking.

2009-11-20T11:56:00.000-08:00

Last week I posted photos of this spot just upstream of the 4th bridge. This area is going to be a "point bar," where the cobbled bank will slope gently down to the water. The point bar will let visitors get right up to the water. In addition, it will allow the stream to spread out during heavy rains, reducing flooding and erosion along the rest of the stream. To create the space for the point bar, the trail is being realigned farther away from the stream. If you know where this drinking fountain is, you can get an idea of the new trail alignment.

This photo shows the current view from the junction of the one- and two-mile trails. As you can see, the whole area has been dramatically opened up. These beautiful sycamores that used to be almost invisible in the thicket of peppers and privet can now be seen in all their glory. You can see the caution tape that the contractor has tied around the trees that are being preserved. Mike Bubalo Construction Company is doing an excellent job of surgically removing the non-native species and leaving the natives--even in some places where they have to literally untangle the invasive species from around and between the natives. A few non-natives are being preserved, like the large palm in the above photo (only the trunk is visible). Even though it is not native, this palm helps stabilize the streambank and removing it would be difficult and costly. Besides, palms are not particularly invasive, so there is little harm in leaving it.

2009-11-12T15:05:00.000-08:00

This is what the area between the 3rd and 4th pedestrian bridges looked like on 10/20/2009. Preliminary clearing had been done to allow equipment access through the stream corridor so the contractor could start removing the muck from the streambed.

And this is what the area looks like today. A tremendous amount of vegetation has been removed from the banks. All debris* is being chipped and the mulch spread on-site. Vegetation has been cleared from the north lake as far downstream as the 4th pedestrian bridge (or rather, where the 4th bridge used to be and will be again). The contractor is being very careful to protect the native vegetation as the exotics and invasives are being removed. The whole stream is being opened up to air and sunlight. The claustrophobic feeling of being choked by the overgrown vegetation is gone.

* One streamside tree was covered with an unknown fungus. As a precaution, that tree was taken to the area south of Willow Street, rather than chipping it up and spreading a fungus that was potentially harmful.

Room to breathe

2009-11-05T14:00:00.001-08:00

You can almost hear these sycamores saying "ahhhh" now that the Brazilian peppers and other invasive species that were crowding around them have been removed. With the other vegetation gone, the magnificent structure of these beautiful trees can be seen.

Some of the trees were so crowded together that they had actually grown into and through each other. It almost looks as if these two trees have created a hybrid, a sort of "Western Brazilian sycamore." It will be interesting to see what the sycamore looks like once the pepper is removed.

Wow!

2009-10-30T13:32:00.000-07:00

The contractor has started removing vegetation from the sides of the stream and the effect is stunning. Removing a patch of overgrown shrubs opens up a whole area to sunlight and opens vistas that no one has seen in years (maybe decades). In consultation with City staff and the project landscape architect, non-native and selected native vegetation is being removed. As you can see in the photo, natives to be preserved in the midst of exotics to be removed are tagged so the heavy equipment operators can easily see what is what. Some natives have to be removed due to their condition or location, but the vast majority of removals are exotic invasives (privet and pepper). We will be re-using all of the vegetation that is being removed--some tree trunks will be used in or around the stream and everything else is being chipped to use as mulch around the Nature Center.

Getting Ready to Remove Vegetation

2009-10-26T11:57:00.000-07:00

Today City staff, the contractor, and the construction manager walked the reach of the stream between the weir and the first place the trail crosses the stream downstream of the weir, talking in detail about vegetation removal. The contractor now knows what vegetation is to be removed and what is to remain. To let the equipment operators easily see what is to be done, bright paint was sprayed on trees that are coming out. In addition to removing a lot of non-natives (mostly Brazilian pepper and privet), these removals will open up the stream to sunlight, making it possible to grow shrubs below the tree canopy and further strengthening the stream banks.

Getting the Muck Out

2009-10-22T16:26:00.001-07:00

I promised to write more about the muck, so today's post is all about muck. The first order of business in restoring the stream is to remove all the material that has accumulated on the bottom so we can create a more natural stream bed. If you have pulled out a branch that was stuck in this muck, you know that the stuff is sticky, gooey, and often smelly. The smell is from the decomposition that happens in an environment without oxygen (anaerobic decomposition). While there is some oxygen in the water, there wasn't much in the muck. But as I mentioned the other day, the muck doesn't smell. We let it dry out for a few days before we started removing it, and it appears that the drying got enough oxygen into the material to stop the anaerobic decomposition. This was really good news and has made this phase much more pleasant than it otherwise might have been.

We are spreading the muck in the undeveloped part of the Nature Center south of Willow Street. You can see it as you drive by from the eastbound lanes. The pile is about 4 feet high and covers about a half of an acre (as of this writing). Unless my math is bad, that's nearly 1,000 cubic yards. Later on, some of this might be mixed with sandy soil and recycled into the new stream banks.

What does the streambed look like without the water?

2009-10-21T10:37:00.000-07:00

Now that the water has been drained out, a lot of the streambed looks like a wide, flat road. As the silt and muck has accumulated over the years, it has filled in all the nooks and crannies that were once there. What is left has almost no variation--no places for water to eddy or swirl, no places for fish to hide, no places where the water can speed up, no places for anything other than the shallow and slow flow from the north lake to the south lake. With no water covering it up, the evenness of the bed is remarkable.

I'm surprised that the muck doesn't smell really bad. After 30 years of anaerobic decomposition under the water, I was prepared for some pretty nasty odors. So far, the material that is being dredged out of the streambed just smells like mud. That's a relief!

Calling all mycologists

2009-10-21T10:21:00.000-07:00

Here are some more examples of fungus found near the stream restoration construction site. Post IDs if you know what these are.

Name that Fungus

2009-10-13T15:06:00.000-07:00

What is this? I assume it is a fungus of some sort. This photo was taken inside the construction area, downstream from the dam separating the stream from the lake, on the streamward side of the walking trail. The whole thing is about 1 foot in diameter.

Please Respect the Trail Closures

2009-10-13T09:05:00.000-07:00

After years of planning and preparation, the Nature Center Stream Restoration is finally under construction. That means that the stream is now a construction site, and, as such, must be closed to the public. Rather than closing the entire Nature Center for the duration, we have closed only those trails that are within the construction area. We have put fencing across the trails at the closure points and put up maps showing which trails are open during construction. For everyone's safety, please respect these closures. When you are out walking the trails and you see a fence blocking the trail, please don't work your way around the fence to continue on the trail, even if other people clearly have done so. It costs us time and money to keep putting the fences back when patrons move them.

We can't put a fence all the way around the stream to cordon off the entire zone--too difficult, too expensive, and would damage too much of the vegetation. Instead, we are counting on every Nature Center visitor to cooperate with the trail closures and stay out of the construction zone.

So when you are out enjoying the beautiful natural environment, please keep your eyes open for construction signs and help us complete the stream restoration on time and within budget.

Critter Patrol

2009-10-08T16:53:00.000-07:00

The stream has been draining since Monday. As it drains, we are doing everything that we can to make sure that no wildlife gets trapped by the receding waters. City of Long Beach staff, construction staff, and Nature Center volunteers have kept sharp eyes on the streambed for the telltale signs that animals may be in danger of getting stuck. A ripple on the water's surface might indicate a fish in a shallow pool. A small movement in the mud could be a crawfish working its way out. A tiny, muddy flip-flop could be a pollywog. All of these signs send the watchers reaching for their nets and buckets, to catch the animals and deliver them to the nearest lake. Hundreds of fish have been rescued, along with dozens of pollywogs, quite a few crawfish, and one turtle.

The rest of the stream water should be out by the end of the day on Friday. Then we will let the muck dry for a few days before the contractor begins taking it out. More about the muck in a future post.

Construction has begun!

2009-10-07T11:53:00.000-07:00

Bright and early on the morning of Monday, October 5, 2009, the crew from Mike Bubalo Construction and PRM staff gathered at the Nature Center to start construction. The first order of business was to identify exactly where the trail closure fencing would go. Once those locations had been determined, Bubalo sandbagged the weir at the north end of the stream and built a dam at the south end to keep water from the lakes out of the stream. Later in the afternoon, Bubalo began pumping water out of the stream, over the dam, and into the south lake.