<i>A large algae bloom in Lake Erie. <a href="https://www.flickr.com/photos/noaa_glerl/36546206732/in/photolist-XFsS1C-XkvfrJ-oqsFDK-4pfcWa-YQNyWV-BM9gvS-YNcv1b-M4yYWb-bhwCfp-XFsPd3-XPCjTv-ogeW1R-YNcvbS-XPCknX-YLCHj5-YQLmVq-YNcuqU-XkvfMy-XPCkdi-XPCjnR-XFsPnS-XN73EW-2982JJC-YSDTWZ-XPCkkc-BLLW2U-YscCo5-YT9MYz-XN73aY-YNDdp7-BLLQuG-YBok15-25EA72N-XRCQDa-ceGTDw-BLLUhS-XPCkwK-26rxTWQ-akvpGa-M4yV1L-YNcvTy-6jM5MN-7Gjz91-a25Y5X-j4CDGU-5HNi39-fob58e-27GV5rY-6rs4ZD-9gtSWX">NOAA Great Lakes/Flickr</a></i>

A large algae bloom in Lake Erie. NOAA Great Lakes/Flickr

We’ve already talked about safety in the D.M.V.’s natural waterways this summer. We mentioned algae then, but it’s in the news now – blue-green algae, also known as cyanobacteria, has been confirmed present in two Montgomery County lakes. It exists in natural bodies of water throughout the United States, and it’s dangerous to humans and pets alike; three dogs died within hours of exposure to the algae in North Carolina last week.

We’ll sit down a with Montgomery County official to tell you where the algae is, how to avoid it, and why.

Produced by Maura Currie


  • Matt Harper Principal Natural Resources Specialist at the Montgomery County Parks Department


  • 12:00:02

    KOJO NNAMDIYou're tuned in to "The Kojo Nnamdi Show" on WAMU 88.5. Welcome. Later in the broadcast, the Georgetown Metro myth. As the story goes, during the early stages of Metro's planning, Georgetown residents blocked the construction of a Metro station in the neighborhood to remain separate from the rest of the District. But just how true is that story? However, first, this summer, we talked about the dangerous bacteria that can lurk in the DMV's rivers. And now, there's concern in Maryland about algae. Cyanobacteria, more commonly known as blue-green algae, has been confirmed in a number of lakes. Algae might not sound scary, but it should be, especially if you have pets who enjoy the water with you. This algae is linked to the deaths of six dogs in Texas, North Carolina and Georgia in the past few weeks. Here to tell you what you need to know is Matt Harper. He is the Principal Natural Resources Specialist at the Montgomery County Parks Department. Matt Harper, thank you for joining us.

  • 12:00:59

    MATT HARPERThanks for having me.

  • 12:01:00

    NNAMDISo, Matt, where are these algae blooms?

  • 12:01:03

    HARPERSo, we have observed these algae blooms isolated to lakes in Montgomery County, within our park system. And the conditions that support the algae that produced this toxin that we're discussing are a byproduct of the algae that needs certain conditions, such as deep water, slow moving water, and then the right time of year will possibly support the conditions for a bloom, which would then create a larger concentrations of the microcystin toxin that creates this concern.

  • 12:01:43

    NNAMDIThis algae has proven dangerous for people, and potentially fatal for pets. What does it do that's so harmful?

  • 12:01:49

    HARPERSo, microcystin is a hepatotoxin, which means that it would affect the function of the liver. So, if ingested in large quantities, then it could affect liver function and be dangerous in that way.

  • 12:02:07

    NNAMDIWe want to note, however, than prolonged exposure shouldn't be an issue under most circumstances in Montgomery County. Can you explain that?

  • 12:02:15

    HARPERYeah. So, you know, since 2009, we've been testing both Lake Needwood and Lake Frank, which are two waterbodies found in Montgomery County Parks, for this toxin. And it is something that has been found since 2009. And, as a result, the thresholds for concern for water recreation activities set by the World Health Organization -- and that's 10 parts per billion. So, if we find concentrations higher than that, then we suggest to patrons that if they do come in contact with the water to wash their hands thoroughly, or whatever body part comes in contact. But it's more prolonged exposure, and even prolonged exposure is not necessarily considered an extreme threat. It's more the ingestion that is the primary concern.

  • 12:03:10

    NNAMDISo, why are dogs the ones we need to be concerned about, here?

  • 12:03:14

    HARPERDogs are traditionally the ones we're concerned with, because they are not as, you know, restrictive in what water they would drink. And they are often -- if they were off leash and unsupervised, they could end up in an area with one of these algae blooms and, you know, potentially ingest and drink the water or spend significant amount of times in an area where concentrations are high where a human may otherwise think, you know, the smell or the color may not seem as appealing.

  • 12:03:48

    NNAMDISo, with the enhanced risks from this algae, are there plans to more aggressively enforce these rules about not swimming and allowing dogs off leash?

  • 12:03:57

    HARPERWell, that's an important note that our park rules and regulations do restrict swimming in waterbodies, and dogs are always meant to be kept on leash. So, if those rules and regulations are followed, then there are no real risks to patrons at these parks.

  • 12:04:16

    NNAMDIWho does that enforcement?

  • 12:04:19

    HARPERWe do actually have a, you know, a series of a number of staff -- maintenance staff and park managers who are in the region, as well as the park police are patrolling throughout. But, again, these are large areas meant for recreating, and there's a number of -- there's an extensive trail network associated with both Lake Frank and Lake Needwood. So, there are a number of people around and, you know, we're never going to have the numbers to be very strictly enforcing this. But, you know, that's why we have posted signs throughout both park systems. At trail heads, we have sort of a media outreach campaign, as well as social media, where we're notifying patrons of this risk.

  • 12:05:00

    NNAMDIOur guest is Matt Harper. He is the Principal Natural Resources Specialist at the Montgomery County Parks Department. We're talking about toxic algae found in lakes in Montgomery County. Marybeth left us a Facebook comment, "Any testing being done right now on other lakes?"

  • 12:05:15

    HARPERSo. No, we have not tested any other lakes this year. We limit our testing to areas where we visually observe these blooms occurring, because that is a correlation to the higher concentrations of this toxin. And, you know, I think it's important to note, too, there a number of different algae species that are found in fresh water systems throughout Maryland. And not all of them are toxic. Even some of these species that we're observing in Lake Frank and Lake Needwood, you know, different strains can be toxic, or have more toxicity than other strains. And we can even go as far as to say that from what we know, you know, individual populations can test toxic one day and not toxic the next. So, just because you're seeing algae does not mean there's a necessarily a threat of toxicity.

  • 12:06:08

    NNAMDIHave these blooms always been in the water? Why is it news when we do identify them?

  • 12:06:13

    HARPERSo, again, this is sort of a seasonal occurrence. The species of algae that we have identified in both of these lakes, it's the primary producer of microcystin is always there. It's a naturally occurring cyanobacteria. And it is only during the warmer summer months when, you know, temperatures reach a certain threshold in the water and, you know, conditions are just right from a precipitation standpoint, as well as the nutrients available in these systems that we actually see the blooms. And this can be hard to predict, and it changes from year to year, and it all depends on what, you know, what the exact conditions are. But it's typically something that we have been observing since 2009, sort of later in the summer then. You know, sort of extends a little bit into the cooler months. But, typically, in the fall is when we see these blooms fall back down.

  • 12:07:15

    NNAMDIYeah. Because a spokesperson for the Maryland Department of the Environment told us that there are four-six advisories for blue-green algae every year. There have been two this year, so far. One in July in Anne Arundel County, and yours in Montgomery County. As you were saying, is this a season issue?

  • 12:07:30

    HARPERYes, typically. These algae are competing with a number of other different species of algae, and it's really this later summer where these can flourish.

  • 12:07:41

    NNAMDIHere now is Susan, in Wheaton. Susan, you're on the air. Go ahead, please.

  • 12:07:46

    SUSANYes. Hi, good morning. I called the Parks Department a couple of days ago when I first heard on one of the national news programs, and they basically said, "Well, we have some information on our website." And I was, like, "Well, I hope you're posting where the lakes are, so people who are going there can see it." The woman I spoke to seemed unaware of the problem. But be that as it may, I did go to your website, and the concern I have is that it does not mention that this can be fatal to dogs. It says it can affect the liver of humans and dogs. And, of course, for dogs, it's much more serious. And every other news story I've seen mentions it, you know, "fatal to dogs." So, I would urge to really be clear in your warnings, both on your website and on the signs you have posted at the lakes. Just quickly, secondly, I live in Wheaton. And when I called I asked -- when I called the Parks Department, I asked, "Well, what about Wheaton Regional Park?" And they said, "Well, that's not our jurisdiction." There's a big lake, Pine Lake, there.

  • 12:08:45

    SUSANThere's another lake at the Martin Luther King Recreation Center. And as for the gentleman stating that they just do a visual inspection, the news stories I've seen about this state that you cannot always even see the algae. So, I would really -- I think there's issue of concern about possibly all the waters in this area. And, specifically, I'm not clear on what you all will be doing about addition body -- you know, lakes that you're not currently monitoring.

  • 12:09:11

    NNAMDIMatt Harper.

  • 12:09:14

    HARPERYeah. So, we do have a number of lakes in our system. And, again, the conditions that these potentially toxic blue-green algae thrive in are very unique, and they require both the nutrients, the nitrogen and phosphorus inputs that are common in more developed areas, as well as the certain depth requirements that create stratification within the lakes, and as well as the temperature and sunlight requirements that, you know, we have seen to be ideal in areas within Lake Frank and Lake Needwood. So, we obviously do have eyes on a number of other lakes in our park system. And we are managing those closely. If we see any indications of these blooms occurring there or any sort of suspicious-looking bloom, we certainly would follow the same protocol to take water samples.

  • 12:10:11

    HARPERWe send them off to the Maryland Department of Environment for laboratory testing, which is the only way you can actually determine whether these blooms are toxic or not. And then, you know, post and notify, as necessary.

  • 12:10:25

    NNAMDIShe mentioned Wheaton Regional Park. And, apparently, you don't have jurisdiction over the lakes and ponds there?

  • 12:10:32

    HARPERNo, we do.

  • 12:10:33


  • 12:10:34

    HARPERWe do. Wheaton Regional Park is one of our most highly visited and well-loved parks in the park system.

  • 12:10:41

    NNAMDIIf you're not a nature scientist, how can you identify this algae? What should you look for and what should you avoid?

  • 12:10:47

    HARPERWell, they come in a number of different forms. So, you know, I think the main thing is that if you see discolored water, it's probably best not to recreate within it, or at least swim in it. The standards that are still set by the World Health Organization are for activities that would potentially create ingestion of the water. No permissible activities are allowed on any of our waterbodies that would really create those sorts of conditions. But out of an abundance of caution, we do post and just notify people that it's not safe to do so, if you do choose to do so. So, I think we have boating and fishing that's sort of the main recreation associated with water at Lake Needwood. And at Lake Frank, there's fishing, both of which, you know, you should not be at risk in ingesting the water.

  • 12:11:46

    NNAMDIWhat does the algae look like?

  • 12:11:47

    HARPERSo, what we've seen from our waterbodies is a species called microcystis originosa, and that one is relatively bright green, and in its bloom, will sort create sort of a scum-green coloration towards the top of the water.

  • 12:12:09

    NNAMDIHere now is Leslie in Rockville, Maryland. Leslie, you're on the air. Go ahead, please.

  • 12:12:14

    LESLIEHi. I remember going to Lake Needwood a few years back, and the sign there actually even said, "Don't even touch the water." So, we left there, concerned. We had a small, little thing in our backyard. And we had a little bit of fish in it, as well. And it would get tons of algae. And we would actually just grab the algae with our hands and throw it out. And after going to Lake Needwood, we got very concerned. So, how do we know that -- and we closed it up. But how do we know that there's none of this bloom, this dangerous toxic algae in our backyard, in a little thing for fish?

  • 12:12:53


  • 12:12:54

    HARPERSo, I would say, as I mentioned before, the only way to truly test is need to send samples to the laboratory. But I would also note that the species that produce toxins are typically only found in larger bodies of water with a depth of greater than four feet, and areas were excess nutrients are sort of draining into it. So, a pond in your backyard would not necessarily be getting the same sort of runoff that one of these regional lakes gets from the surrounding area. So, even if you did have it or found it in small concentrations, it's not an issue. It's really only when it's in its bloom form, you know, when you see these algae blooms, that it becomes a hazard. And I think even if anybody who have been around these lakes has seen one of these blooms, they're often -- these are large bodies of water, and the blooms occur in very isolated areas in small spots.

  • 12:13:54

    HARPERSo, if you're on one side of the lake, you may, you know, be in an area where there's no microcystin present, whereas another area where you're seeing some discoloration. You might see higher concentrations.

  • 12:14:05

    NNAMDIDo we know of any algae-related illnesses or deaths that have ever occurred in Maryland?

  • 12:14:12

    HARPERI am not the expert on that, so I wouldn't really feel comfortable speaking to that.

  • 12:14:20

    NNAMDIIf pet dogs are at such risk from this, what's the expected impact on wildlife?

  • 12:14:26

    HARPERSo, there is the possibility that, you know, aquatic organisms within the lake would be exposed to this toxin. So, fish and macroinvertebrates and birds that might be eating the fish could potentially be exposed to the toxin. We have not noted any major illnesses or deaths of wildlife. But it's certainly possible. And I think the likelihood is low, though, because of the size of the lakes and, like I said, the sort of localized existence of these blooms. But we will be monitoring this over the long term.

  • 12:15:08

    NNAMDIIs it therefore safe to eat the fish you catch in the lake, for example?

  • 12:15:12

    HARPERIt is safe to eat properly cooked mussel meat of fish that are --

  • 12:15:16

    NNAMDINot raw? You don't want to it that.

  • 12:15:18

    HARPERNot raw, and especially not the liver of these organs. That's sort of where the toxin would be accumulating.

  • 12:15:25

    NNAMDIHere's Gary in Sterling, Virginia. Gary, you're on the air. Go ahead, please.

  • 12:15:29

    GARYThank you very much. I was curious. Have you all ever thought of using something like yeast or a bacterial digestant, something like Ridd X, you know, what you put in your septic tank? Because I've sprayed that stuff on flooded basements where we had mildew, and it consumed all the mildew. Didn't have any smell.

  • 12:15:58

    NNAMDIWhether it's yeast or not, are there plans to treat these blooms, say, chemically? Or do we just have to wait it out?

  • 12:16:04

    HARPERSo, this is difficult question, and one that we've given a lot of thought. It's very difficult to treat this holistically when you have a number of different other algae species and organisms living in these waterbodies. So, whatever is done needs to be done very carefully, so as not to affect -- or negatively affect the other organisms that live in there. You know, these algae species are primary producers, and they are an important part of the food chain. Even the ones that are producing the harmful toxins. So, you know, we have to keep that in mind because the organisms do -- there are a number of organisms that do rely upon them. And they are producing oxygen as they fix CO2. You know, that's part of the food chain. So, it's a very difficult thing. There's a lot of research going on as to how to do that in larger natural areas.

  • 12:17:03

    HARPERThere's biological controls being looked at. Some researchers have found some success with the use of barley straw. But a lot of the chemical treatment is sort of reserved for bodies of water that are being used as water supplies, and there are a number of chemical treatments that can be used for treating water that will be used for drinking.

  • 12:17:25

    NNAMDIHow worried should people be about this? Should they avoid the lakes altogether?

  • 12:17:29

    HARPERI would say no. I think these are both beautiful areas to recreate, and, you know, they're very nice this time of year. So, we suggest that you can -- as long as you're following the rules and regulations of the park system, which are in place year-round, you will continue to enjoy these areas, and enjoy the natural beauty that they provide.

  • 12:17:50

    NNAMDIHere's Susan in Alexandria, Virginia. Susan, your turn.

  • 12:17:53

    SUSANHi, Kojo. Thank you for this conversation. I am a consumer of an edible type of blue-green algae -- another type, not the one that grows in Maryland. It's called a Aphanizomenon flos-aquae, and many, many health-conscious consumers have been eating this for many, many years. And I just -- I called because some people might have some people might have the question, "Oh, am I getting a kind of algae that's not safe?"

  • 12:18:23

    NNAMDIWhat's the one that you eat called, again?

  • 12:18:26

    SUSANAphanizomenon flos-aquae. It's from --

  • 12:18:30

    NNAMDISay that quickly three times, Matt. Go ahead.

  • 12:18:32

    HARPERYeah. Please, no. All right, so, yeah, there's -- I think it's tricky, because there are a number of different species of blue-green algae and, you know, there are species of Aphanizomenon that are toxin-producing. But, again, not all of them are. And the conditions that create that toxicity are not known at this point and time, are not very well-known. So, there's a lot of research going on to sort of make those differentiations. But we use, you know, we, as people, use all sorts of different types of algae in our everyday lives and, you know, most of the vast majority of it is not of concern. But there are, you know, situations where these toxins can be produced. And, again, most of the time, these are naturally occurring. So, most of the time, these things are around, and small amounts are being produced. But it's when the blooms occur in these unique situations that their concern arises.

  • 12:19:32

    NNAMDIIf someone is worried about having come into contact with this particular algae bloom, what should they do?

  • 12:19:39

    HARPERWell, we suggest if it's just sort of skin contact to wash your hands thoroughly or your body part thoroughly, if ingestion occurs, then I would suggest seeing a healthcare provider.

  • 12:19:51

    NNAMDIMatt Harper is the Principal Natural Resources Specialist at the Montgomery County Parks Department. Thank you so much for joining us.

  • 12:19:57

    HARPERThanks for having me.

  • 12:19:58

    NNAMDIGoing to take a short break. When we come back, we'll look into the Georgetown Metro myth. I'm Kojo Nnamdi.

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