Mosquitoes versus our ponds

Mosquitoes are rapidly becoming intolerable again in north Galveston County, and there will likely be the usual debate as to whether they are primarily attributable to all the rain that has created standing water in local areas, or tidal impacts to saltwater marshes.

Our last significant outbreak occurred in October 2011, when Galveston County Mosquito Control (note that their URL contains an annoying buzz that you may not want resonating throughout your cube farm, if you work in one) made a PR blunder in stating that they weren't actually that bad.  In fact, they were horrible, and the ensuing recant described why. 

October's outbreak was exacerbated by the earlier effects of Tropical Storm Lee, which caused higher-than-normal tides to flood saltwater marshes, prompting mosquitoes to hatch out.   (If you remember, T.S. Lee was probably THE most expensive and devastating tropical system that Texas never had, because the winds fueled the wildfires that wiped out parts of Austin suburbia and, of course, Bastrop.)

At this point, I don't know if this latest batch of mosquitoes is primarily the result of local rainfall saturation, or salt-marsh hatch-outs.  But while basking in the outdoor air yesterday, I did receive an interesting question from a Centerpointe resident, the inquiry being punctuated by repeated slaps at arms and legs: Why isn't the retention pond behind the apartment complex (Walker Commons)  drained just as our neighborhood's own stormwater retention ponds are? 

Centerpointe's dry-bottom ponds will retain some water immediately after heavy rains, but then they go dry again, presumably minimizing the number of mosquitoes that are able to hatch out of them.  But that large pond behind the apartments is permanent - it's full of water all the time. 

Google street view looking north from League City Parkway.

This is a darned good question, and the answer is as follows: That is NOT a stormwater retention pond.  That's an old flooded sand pit (these things are also called borrow pits). 

At some point between 1943 and 1955, sandy fill was excavated from that area, almost certainly for construction purposes.  In order to illustrate the history of that pond's development, it's most useful to work backwards in time from our present-day familiar reference point:

Topographic map last updated in 2010.  You can see the distinctive pattern of Centerpointe's streets near the words "League City", and the pond toward lower right.

Same area in 1995, pond still visible.  Centerpointe's construction would not start for approximately another five years.

Same area in 1955, with the pond appearing as purple stipple, indicating that it is a new feature added since the previous map, which is shown below.  IH-45 / Hwy 75 is referred to on the map as a "freeway" for the first time.

Approximately the same area in 1943.  No pond was present at that time.  IH-45 was referred to only by its original name, which was Highway 75, indicating that it was not a "freeway" at that time.

All map grabs courtesy of www.usgs.gov.

Given that pond's location and its age, it was almost certainly used to supply fill for the original construction of the Gulf Freeway.  That history is strongly reflected in the topographic map series shown above.

And if you REALLY want some ancient history on this area, you can look at the 1929 topographic map that is available on line.  At that time, the only way to Galveston was via the original public right-of-way, what we now call "Old Galveston Road" - aka Highway 3.

You can see similar borrow pits (or "sand pits") all around greater Houston.  It costs a lot of money to transport the enormous amounts of dirt fill needed for freeway construction.  Therefore, TxDOT tends to acquire that material as close to the construction area as possible.  In some cases, the old sand pits have been used to enhance property development (e.g., the apartment complexes around the Windmill Lakes up by Almeda Road; Mammoth Lake Scuba Park about 50 miles from here in Clute is an example of an old sand pit permanently filled with groundwater and put to a productive commercial use).

That being said, this League City Parkway pond is a bit unusual in the degree to which it is fortified with fencing, signage, gates, etc.  Part of that is undoubtedly for liability reasons, as unauthorized and unsupervised use of these ponds sometimes leads to drownings, such as this one from last year.  But there's potentially another reason why security at that pond is relatively tight:  word on the street says that the pond's owners keep it stocked with some really awesome fish.  They don't want trespass leading to accidental drownings, but they also don't want people to steal their fish.  But that's just a rumor I heard on the street.
:-)

That news article cited above makes note of the fact that these pits can be up to sixty feet deep!! Hence the inability to drain them: even if they could be pumped dry, they're usually so deep that they would simply fill back up with groundwater again. 

Despite the inability to drain that pond, if you contemplate the sum total of information above, you'll realize that it is not likely a primary source of Centerpointe's mosquitoes because:

• A healthy stock of fish will keep mosquito larvae under control, and
• If it were a big mosquito-producer, we would experience heavy mosquitoes here in Centerpointe more-or-less continually, and we clearly do not. 

What DOES tend to influence our neighborhood mosquito misery is how often the nearby fields are mowed.  High grass does not produce new mosquitoes, but it gives abundant shelter to the mosquitoes that migrate out of the coastal salt marshes and into our area.  A good mowing of the fields east of Centerpointe often yields an immediate reduction in mosquito numbers here.  So if you have an urge to complain about the little buggers, you can do two things:

1. Contact Galveston County Mosquito Control at 800-842-5622 to request a spraying, and
2. Call the realtors posted on the "For Sale" signs in that field and request that the property owner have the weeds be mowed down.