A Review of Jenks Lake Bianca Patti Cara Taylor Ben Golan Bianca Patti, Historian About halfway up to Big Bear, located in the San Bernardino National Forest, lies a small recreational fishing lake named Jenks Lake. Built in the 1870’s by Captain Lorin Shaw Jenks, the lake’s original purpose was to serve as a trout pond where Captain Jenks could spawn trout and sell them for profit. Jenks Lake was built by diverting water from the Santa Ana River into the man-‐made lake bed to be used as a reservoir. Captain Jenks also built a lodge on the same area of land, but unfortunately it was shut down due to its inaccessibility; lodgers had to travel three days via burro ride just to get there. Since then Jenks Lake has been used by different groups of people for various reasons, but today it is strictly for fishing as swimming is no longer allowed. In the late 1800s, industrial logging in Southern California was on the rise; sawmills were popping up left and right and by the year 1900 there were 22 sawmills up and running throughout the Big Bear mountains. Jenks Lake is located alongside one of these old logging roads. Since 1891, national forests had been completely protected from any type of commercial exploitation, but on June 4, 1897, a bill was passed with an appropriations rider that opened the forests up for timber sales (Hanson, 1999). This industrial activity began an almost complete deforestation of the trees in the mountains and residents of Big Bear and the surrounding areas became upset about the dramatic exploitation of the land and the sheer volume of trees that were being eliminated. Protests ensued and someone even anonymously started a forest fire. The citizens petitioned to President Theodore Roosevelt to have the protected area expanded, but even after that, some of the sawmills continued to operate. The longest running sawmill finally closed down in the 1960’s. Although the intentional forest fire protest was extreme, industrial logging is much more dangerous to our forests than such fires. In fact, “logging on national forests increases the risk of forest fires more than any other human activity” (Hanson, 1999). This is due to fuel accumulation and the fact that timber harvesting alters the structure of the forest. The aftermath of sawmills continues to be present today in the form of floods, mudslides, and contaminated waters. In 1884 the Big Bear Lake Dam was built in order to provide more water for irrigation and farming in the city of Redlands. Pretty soon, the dam was unable to hold as much water as was needed to meet the increasing agricultural needs of the Redlands and Highland areas. The dam was rebuilt in 1910 and is now 250 feet downstream from where it originally stood. Because Bear Creek is the first major tributary of the Santa Ana River which was used to create Jenks Lake, the reconstruction of the dam could have had some effect on the chemistry of Jenks Lake for a brief period of time (Mitchell, 2006). As was mentioned earlier, Jenks Lake is a reservoir that overflows into Barton Creek and an article written by R.M. Baxter goes into explicit detail about the impact dams have on the environment as well as different types of bodies of water. “Because reservoirs are frequently built on streams carrying a heavy sediment load, the deposition and distribution of this material within the reservoir are often more important in reservoirs than they are in natural lakes. Therefore constraints on the nature of the developing biological community are imposed when a new reservoir is constructed” (Baxter, 1977). This suggests that not only does damming a lake effect the surrounding environment and ecosystems, but it also has an effect on the chemistry of the lake frequently, depending on the influx of stream water entering the lake. As time went by, camping around Jenks Lake became more popular and National Forest camp sites were established for the public. In 1924, a Christian summer camp, Camp La Verne opened up near the lake, and for many summers campers used the water as a recreational swimming hole (Herndon). Because the lake is a reservoir, it is possible that swimming was eventually prohibited in order to prevent serious water contamination. Aside from camping in the surrounding areas, the only real recreational activity currently available at Jenks Lake is fishing. Boats are allowed only if they are non-‐motorized. Captain Jenks started off stocking the lake with exclusively trout, but presently the fish stocked in the lake are blue gill, sunfish, largemouth bass and rainbow trout. Since the fish are not indigenous to the lake and have to be restocked by human beings, it is not difficult to imagine that there are some consequences; one of those being an impact on insect population and emergence. People do not usually think of insects right away when thinking about the environmental effects of stocking fish, but insects are crucial to the survival of many other creatures. According to a study conducted in 2008 that was examining the effects of different stocking scenarios in mountain lakes noted that, “Sport fish such as rainbow trout and brook trout are often top predators in aquatic systems and feed heavily on larval and emerging insects. These fishes have been introduced to many formerly fishless lakes and streams throughout the world for recreation. Where trout are introduced, a proportion of the biomass that formerly would have emerged and supported terrestrial life is diverted to trout” (Lawler, Piovia-‐Scott, Pope, 2008). The multiple species of fish in Jenks Lake do not necessarily eat the same insects and this could potentially cause problems for the land creatures surrounding the lake. Upon visiting the lake, it was much smaller and much cleaner than I had expected it to be. I hadn’t expected it to be dirty necessarily, but when we were conducting our tests, the water was impressively clear. Plants and even a fish swimming around were visible from the dock looking down into the water and the surrounding area of the lake appeared to be very well-‐maintained. There was a gentleman fishing on the dock and several others around the shore, but it was by no means crowded. It seemed like a very relaxing place to spend a quiet afternoon and I may have to visit again at some point. During the research stage of this process it was unclear as to where exactly the camp sites were, but when we got there it was clear that there was no camping directly on the shore of the lake. The campsites were a bit of a walking distance away and the only amenities directly surrounding the shore were a few benches and tables and a restroom up the stair case to the parking lot. This probably helps to contribute to the cleanliness of the lake by preventing opportunities for contamination. There is also a biking trail that surrounds a portion of the lake. I did not observe many insects that I can remember specifically, but there were a good amount of lizards and squirrels running around. I wonder if the lack of insect presence has anything to do with the information presented earlier about fish stocking and insect population. The lake was in a pretty heavily wooded area and it made me appreciative that the logging industry was put to an end long ago before any more of the beautiful trees could be cut down. Although it was small and not too exciting, our group had an enjoyable overall experience at the lake and the results of our testing indicate that the water is pretty clean. However, I do believe if we had a non-‐motorized boat, we could have collected more data in order to compare the different test sites of the lake because of the sediment deposits that may be variable throughout the water. Bianca’s Bibliography Baxter, R.M. Annual Review of Ecology and Systematics 1977, 8, 255-‐283. Hanson, Chad. Earth Island Journal 1999, 14, 1-‐16. Herndon, Summer. http://www.camplaverne.org/History.html (accessed November 2014). Mitchell, Patrick. Wilderness Press 2006, 10. Pope, Karen L.; Piovia-‐Scott, Jonah; Lawler, Sharon P. Freshwater Biology 2008, 54, 982-‐993. Cara Taylor, GIS Specialist Jenks Lake is a recreational lake site. This is proven in the numerous campgrounds surrounding the lake, the popularity of fishing, and the trail heads surrounding the lake. It is also proven in the lack of industry and residential population. The lake is a fair distance from any major cities (the nearest being Big Bear Lake, CA and Redlands, CA located about 27 miles from Jenks). There are also no residential housing areas—only a few scattered privates homes. In the map below, I’ve highlighted the recreational uses of the lake. The green push-‐pin at the top left of the map reveals that the land around Jenks Lake is a part of San Bernardino National Forest. It is one of Southern California’s largest and most frequented national forests due to the abundance of trails, campgrounds, fishing, and more. I considered this factoid important because Jenks Lake being located within a national forest proves its proximity to recreation and its likelihood of having higher foot traffic than lakes in less known regions. The blue and white tent icon adjacent to the green push-‐pin mentioned above, highlights the use of camping in the area surrounding Jenks. It is the Barton Flats Campground, which is one of the larger campgrounds located in the Barton Flats plain. This plain occupies a large portion of the land around Jenks Lake, and is home to more than 25 campgrounds (the densest collection of campgrounds in any national forest). These campgrounds include: San Gorgonio Capground, Camp Pine Mountain, Camp Nawakwa, Camp Edwards, Camp Tulakes, and more. This plain welcomes approximately 30,000 children per year for camping (Harris p. 121-‐122). The other two tent icons are to show more campgrounds. Just above the left corner of the lake that has grass and a wooden sign in front of a tree is the trailhead icon. It marks the trailhead nearest to the lake that extends NE and NW. It is one of many trails that surround the lake. As mentioned before, Jenks is in San Bernardino National Forest, a region packed with more than 200 hiking trails. I found the presence of a trailhead so close to the lake important because it is a recreational site and a site that will lead travelers to the beautiful lake. Visitors of the lake can find picnic tables to rest and eat at. These are marked by the rest area icon (an image of a wooden picnic table in front of a tree). This is just another representation of the recreational use of the lake. Finally, I wanted to point out the main attraction to the lake itself: fishing. The green stickpin located some distance into the water on the map shows the location of the dock at Jenks Lake. This dock extends from the soil to about the center of the length of the lake. It’s a wooden dock that has a hole in the center. Both the center hole and the outer portion of the dock are ideal spots for fishing and/or taking in the view of the lake. There are no motor boats allowed on the water, therefore a lot of deep water fishing happens at the dock, and there was a man fishing from it when we visited. Kayaks and canoes are permitted but we didn’t see any on the water when we visited the lake. Fishing is a large industry in the region at both Jenks Lake and the nearby Santa Ana River. Blue-‐gill, sunfish, large-‐mouth bass, and rainbow trout can be found in the lake. There is no swimming allowed in the lake, and while I was unable to find an explanation for it, I can assume that it’s a way to keep pollutants from sunscreen and other chemicals on human bodies that might harm the almost pristine chemistry of the lake. The map above is showing the points at which we took our data on the day we visited the lake, as well as possible sites of pollution. The sampling site on the far left was chosen when we arrived at the lake because it had a high concentration of plants and a green film on the water’s surface. It was also the site of a large log that extended almost across the lake to the other side. We found this spot to be important because of the plant life and murkiness, considering the majority of the lake was very clear, we wanted to sample in an area that had somewhat differing qualities. Moving from left to right, the next sampling site is at the edge of the dock. We used this spot to take out deep water sample. Since we did not have a boat, we could not make it to the center of the lake, and decided to take our deep water sample at a walkable spot. The importance of taking a deep water sample is to find out how much of a temperature drop occurs and to see the possible affects of plant and fish life deeper down. the next point was taken at that point just to collect data at a point far from the previous ones. The opposite side of the lake potentially may have presented different results due to wind direction, pollutants, etc. The last point was taken right near a tributary (Frog Creek). We wanted to take a sample at this point to see if the inflow of water from another source would affect the chemistry. However, I believe at this time Frog Creek is fairly dry from drought and might not have had a significant impact on our data. Despite our thorough consideration of where to collect data, the numbers we received did not range too drastically. I think this might have been due to the cleanliness and consistency of the lake. It’s a oligotrophic lake and is therefore very clear and mostly free of particulate matter that would affect the chemistry. In green I highlighted the parking lot and Jenks Lake Rd. W. (the green box and line). The green line leading off the map is that road that leads from highway CA-‐38 to the parking lot for Jenks. The highway is a source of pollution due to the NOx gases being emitted from car engines. However, the highway is further from the actual lake, and Jenks Lake Rd. is a more secluded lower traffic road. The parking lot is also not very large, and is located on a hill, and you have to walk down a staircase to get to the lake. All of this means that the lake is fairly sheltered from car emissions, which would be the main pollutant in the general area. There are almost no homes and no industry in the area. Also, the prohibition of motorized boats and swimming eliminates even more pollutants. The one thing that is not monitored as well at this lake is trash. So, there are very few sources polluting this lake, which is seen in this map by the seclusion of the lake from sources of pollution such as highways, factories, etc. I found it important to show this on a map because Jenks is a place with limed information about it. Seeing the layout of the lake helps someone that does not know much (and cannot find information) about the lake. Below are two images that display important environmental behaviors of the area surrounding Jenks Lake. As mentioned before, the lake is not polluted by much. However, there does exist some interesting information about the physical environment around the lake. The first is an imagery map that shows the soil albedo of the land. The albedo, or reflective power of a surface, is measured on a low-‐to-‐
high scale of 0-‐1. This layer is shown on the map with white and gray. White is a 1 on the scale, and gray is a 0. The soil at Jenks has an albedo of approximately 0.21, or less than 25% (fairly low), and is shown by the gray color on the map. This means that the soil absorbs a lot of sunlight and reflects very little. The next image shows the USA Wildland Fire Potential layer on the imagery map. It’s a measurement of the area’s potential for wildfires. The scale that measures this potential is low-‐to-‐high from 1-‐7. Each number has a color associated with it. On the map below, a large portion of the immediate land around the lake is red, and further out is yellow. Red is a 5/7 on the scale and yellow is a 3/7. According to the map layer’s calculations, the fire potential in the area is at a 5/7 which is very high. As you can see on the map, the area surrounding Jenks Lake has a high concentration of trees (the main species being Canyon Live Oak). All trees absorb sunlight, and such a large number of trees results in a large amount of heat absorption. Also, as shown earlier, the low albedo of the soil causes a lot of sunlight (heat) to be absorbed by the land. From the information I’ve gathered this past semester, I know that if an area of land is absorbing a lot of heat, it is prone to catching fire. While there have not been any major fires in this area, I’ve learned that the Earth is getting warmer as a result of a weaker stratosphere that is not stopping radiation from reaching Earth’s surface that it used to. More sunlight touching the surface is going to increasingly put areas like Jenks in danger of serious fires, and destruction. So, while there are very few pollutants affecting Jenks Lake at the moment—pollution globally is causing the land around Jenks to be warmer and more susceptible to damaging fires. Ben Golan, Environmental Consultant When one pictures Southern California, one imagines beaches, clubs, celebrities and big cities. Tourists flock in from around the world to visit Hollywood in hopes of seeing a movie star. Or they come to see the beaches and swim in the warm Pacific Ocean. Or they come for the nightlife to drink and dance. Or they come for all three. However, many of the tourists miss out on a major attraction: The San Bernardino National Forest. Although Southern California is not widely known for its forests, the San Bernardino National forest is quite large, taking up 818,250 acres of the San Bernardino and San Jacinto Mountain Ranges (8). This forest was designated a national forest in 1907 after a significant amount of mining, timber and grazing had taken a severe toll on the well-‐being of the forest, soil, wildlife and bodies of water (8). The land was felled and overgrazed by gold-‐miners, the timber industry and the growing citrus industry (8). However, despite it’s battered past, the forest’s bruises are fading and it has become a public land set aside for the conservation of natural resources. (10) As one can see in the map provided, this forest offers many natural resources including trees, water, minerals, livestock range, recreation and wildlife (8). The San Bernardino National Forest is a temperate coniferous forest; characterized by warm summers, cool winters and precipitation year round (4). It is home to thousands of plant species and 440 (recorded) wildlife species, 156 of which are endangered (8). This forest with its abundant resources is a mainstay of Southern California and should be a bigger attraction to tourists and SoCal inhabitants alike. However, even lesser known and less admired than the San Bernardino National Forest itself is a small lake nestled within the forest: Jenks Lake. Jenks Lake is located to the Southeast of Big Bear Lake, right next to Highway 38 (34.164 degrees North, 116.882 degrees West) (1). It is an endorheic lake located at an elevation of 6,739 feet (2,054 meters) (4 and 1). As mentioned before, it is located within a temperate coniferous forest so Jenks Lake is subject to warm summers, cool winters and precipitation year round (4). On the day of our visit, October 16th, we tested three sites along the lake and found: The average air temperature was 20.3 degrees Celsius The average water temperature was 16.8 degrees Celsius The average pH level was 8.1 The average amount of dissolved oxygen was 8.5 mg/L The average amount of phosphorous was 28.8 ppm And there was very little to no nitrogen present in the water Based on the data collected, we have concluded that Jenks Lake is eutrophic. This is evidenced by the basic 8.1 pH level of the lake proving that there is a high amount of photosynthesis occurring in the lake (10). It is further evidenced by the amount of dissolved oxygen and the high amount of phosphorous present (6 and 10). And it is evidenced when one observes the lake first hand. There is a large amount of life present in small Jenks Lake. The water is murky and the lake houses many aquatic plants and fish (including bass, catfish, bluegill and rainbow trout) (7). There are also ducks, small rodents/mammals and a few large mammals that use the lake. One of which are humans. The human use of Jenks Lake and the San Bernardino National Forest has been extensive to say the least. As mentioned before, an unsustainable amount of mining, timbering and grazing took place in this area during the 17th century (8). Today, the national park is not as exploited as it once was; however, the public still continues to use the land in other ways (8): Roads and Trail Mileage Pacific Crest Trail Motorized Trails Non-‐motorized Trails Unpaved Roads Cultural and Historic Features Prehistoric Archaeological Sites Historical Archaeological Sites Multi-‐Component Sites Facilities Visitor Centers Family Campgrounds Group Campgrounds Picnic Areas Equestrian Campgrounds Accessible Fishing Piers Staging Areas For Motorized Trails Trailering Sites For Motorized Trails 160 38 414 1,270 616 330 43 3 25 20 13 4 2 2 8 Special Uses Recreation Residences Organization Camps Winter Recreation Resorts Target Shooting Ranges 769 26 4 3 These recreational activities take place throughout the entire San Bernardino National Forest. But more specific to Jenks Lake is fishing and canoeing (canoes can be rented). Although not many visit Jenks Lake, the few that do are mostly fishing. Because this lake has no tributaries, and therefore no “upstream influences”, this is the biggest anthropogenic influence. But this is not to say that this is the only anthropogenic influence. Litter can be found around the shore of Jenks, showing evidence of neglect and feeding the wildlife. And although these anthropogenic influences do not seem to seriously impact the state of Jenks Lake, they could become a problem in the future. As of right now, the management of Jenks Lake has been implemented by the Endangered Species Act and the Forest Reserve Act of 1891, putting the US Fish and Wildlife Service and the Forestry Service in charge of Jenks Lake and its surrounding environment (2). I personally believe that these services are doing a good job of maintaining and protecting this national park and its bodies of water. Jenks Lake is in a healthy state with healthy levels of dissolved oxygen, phosphorous, pH levels and biodiversity. And although the surrounding forest contains roads, trails, buildings and designated recreational areas, the forest seems to be healthy and able to properly house wildlife. The only consistent problem that we noticed was the litter. It was not a serious issue but it was an issue nonetheless, and if not treated properly it can become a bigger issue. More trashcans around the perimeter of the lake and a stricter no littering policy along with better enforcement and clean up strategies could easily solve this problem. This would not take a lot of money or effort on the part of the US Fish and Wildlife Service or the Forestry Service and could save this healthy eutrophic lake from becoming an unhealthy hypereutrophic lake. Although this lake is small and provides little influence on the San Bernardino Forest ecosystem, it still provides nourishment and shelter to many species. It provides a priceless aesthetic value and a monetary value in the form of jobs. The maintenance of such a small lake is simple and is certainly worth all it has to offer. A small gem nonetheless, Jenks lake is still a gem. Ben’s Citations: (1) Google Maps. Jenks Lake. https://www.google.com/maps/place/Jenks+Lake,+San+Bernardino+National+For
est,+California+92305/@34. 643373,-‐
116.8818314,306m/data=!3m1!1e3!4m2!3m1!1s0x80db4b65a97d5651:0xad3958f
a90d8402a (accessed November 10, 2014). (2) Minnich, R. A.; Barbour, M. G.; Burk, J. H.; Fernau, R. F. Sixty Years of Change in Californian Conifer Forests of the San Bernardino Mountains. Conservation Biology. 1995, 9, 902-‐914. (3) NCSU Water Quality Group. Phosphorous. http://www.water.ncsu.edu/watershedss/info/phos.html (accessed October 16, 2014). (4) Reynolds, S.; Rohli, R.; Johnson, J.; Waylen, P.; Francek, M. Exploring Physical Geography; McGraw-‐Hill: New York, 2014. (5) Rogora, M.; Mosello, R.; Arisci, S. The Effect of Climate Warming on the Hydrochemistry of Alpine Lakes. Water, Air, and Soil Pollution. 2003, 148, 347-‐361. (6) State of Washington Department of Ecology. A Citizen’s Guide to Understanding and Monitoring Lakes and Streams. http://www.ecy.wa.gov/programs/wq/plants/management/joysmanual/ph.html (accessed October 16, 2014). (7) United States Department of Agriculture’s Forest Service. Lake Jenks Day Use Area. http://www.fs.usda.gov/recarea/sbnf/recarea/?recid=26537 (accessed September 17, 2014). (8) United States Department of Agriculture’s Forest Service. San Bernardino National Forest Inventory. http://www.fs.usda.gov/main/sbnf/about-‐forest (accessed September 17, 2014) (9) United States Department of Agriculture’s Forest Service. Recreation Fee Areas and Sites. http://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5259563.html (accessed November 10, 2014). (10) Water Encyclopedia: Science and Issues. Lake Health, Assessing. http://www.waterencyclopedia.com/Hy-‐La/Lake-‐Health-‐Assessing.html (accessed October 16, 2014).