As Hurricane Beta traversed northward across the Gulf of Mexico in late September, outgoing swell propagated into the lower Texas coastal waters on September 20th through the 22nd. This swell was powerful enough to push water into the dunes across South Padre Island around high tide, which occurred at 7:30 PM CDT on the 20th and 9:37 PM CDT on the 21st. The highest level that was reported was 2.42 feet above Mean Higher-High Water (MHHW; or the level above normally dry ground at the shoreline) at 3:24 AM CDT on the 21st and 2.54 feet above MHHW at 11:24 PM CDT also on the 21st. Levels remained above 1.25 feet MHHW for several hours surrounding the occurrence of high tide on both evenings of September 20th through the 21st and again on the 21st through the 22nd. This activity was enough to cause some coastal erosion.
Farther up the coast, similar wave action and minor coastal flooding was likely - but there were no comparative measurements based on MHHW.

Storm Surge/Tide in COASTAL CAMERON, TEXAS
From 19-SEP-20 14:30:00 to 20-SEP-20 06:00:00 (CST-6)
Crop damage: 0.00K
Reported by: NWS Employee

An NWS survey of tidal run-up and overwash on South Padre Island found significant dune erosion at many of City and County beach access points between Isla Blanca Park and Clayton's Beach Bar.  Beta's water eroded more dunes that began with run-up associated with Hurricane Laura in late August. Though water levels during the time of the run-up (through the high tide cycle) were above 1.5 feet above Mean Higher High Water (MHHW), the strongest push of wave energy occurred at this time (high combined seas and long period swell from the east).

Storm Surge/Tide in COASTAL CAMERON, TEXAS
From 20-SEP-20 17:30:00 to 21-SEP-20 07:00:00 (CST-6)
Crop damage: 0.00K
Reported by: NWS Employee

An NWS survey of tidal run-up and overwash on South Padre Island found a second day of significant dune erosion at many of City and County beach access points between Isla Blanca Park and Clayton's Beach Bar.  Beta's water eroded more dunes that began with run-up associated with Hurricane Laura in late August. Water levels on this day peaked just below the highest for the event, reaching 2.42 feet above Mean Higher High Water (MHHW) at 218-224 AM CST on the 21st. Run-up was similar to that from late on the 19th/early on the 20th as landward push of sea water was slightly less.

Storm Surge/Tide in COASTAL CAMERON, TEXAS
From 21-SEP-20 18:00:00 to 22-SEP-20 01:45:00 (CST-6)
Crop damage: 0.00K
Reported by: C-MAN Station

The NOAA tide gage at Brazos Santiago recorded a peak value  of 2.54 feet above Mean Higher High Water (MHHW) at 10:24 PM CST on September 21st.  However, notably less landward push of sea water caused only minimal erosion and run-up toward the dunes during this particularly high tide.  Nearby gages at Port Isabel and South Padre Island Coast Guard Station, along the western bay shore and eastern bay shore of Laguna Madre, recorded 2.59 feet (11 PM CST) and 2.5 feet (10:36 PM CST) above MHHW; the Realitos Peninsula location at the mouth of the Arroyo Colorado in Laguna Madre recorded 2.52 feet (12:42 AM, September 21). within an hour or two of the report at Port Isabel.

Storm Surge/Tide in COASTAL WILLACY, TEXAS
From 20-SEP-20 21:00:00 to 21-SEP-20 00:00:00 (CST-6)
Crop damage: 0.00K
Reported by: C-MAN Station

A tide gage at Port Mansfield (inside Laguna Madre) recorded a peak value of 1.61 feet above Mean Sea Level (MSL) at 10:06 PM CST on September 20th.  This mini-high tide corresponded closely to high tide times along the coast farther south, and it is assumed that minor coastal flooding in the form of tidal run-up slightly into the dunes of the Willacy County Beaches near Port Mansfield occurred at this time. It is unknown exactly how much water moved into, or calved, the dunes (which had been previously eroded from Hanna in late July and Laura in late August).

Storm Surge/Tide in COASTAL WILLACY, TEXAS
From 19-SEP-20 15:30:00 to 20-SEP-20 07:00:00 (CST-6)
Crop damage: 0.00K
Reported by: C-MAN Station

A tide gage at Port Mansfield (inside Laguna Madre) recorded a peak value of 1.39 feet above Mean Sea Level (MSL) at 7 AM CST on September 20th.  However, the location inside Laguna Madre was likely unrepresentative of conditions along the barrier island farther south, down to the Cameron County line.  An NWS survey on South Padre Island found significant beach erosion during the high tide cycle during the evening of the 19th, a result of strong landward push of high seas and swell. Therefore, times listed here are a proxy to similar impacts just 10 to 20 miles farther south on September 19th.

Storm Surge/Tide in COASTAL WILLACY, TEXAS
From 21-SEP-20 17:30:00 to 22-SEP-20 23:59:00 (CST-6)
Crop damage: 0.00K
Reported by: C-MAN Station

A tide gage at Port Mansfield (inside Laguna Madre) rose above 1.5 feet above Mean Sea Level (MSL) around 6:30 PM September 21, and continued well above 1.5 feet through the 23rd, peaking at 1.80 MSL at 3:24 PM on the 22nd. Though tide levels inside Laguna Madre remained high through the 23rd, the lack of landward push of water from Beta that day as the cyclone had already made landfall on the 22nd along the central Texas coast, well north of Port Mansfield, suggested that landward push of water had ended much earlier.  An NWS survey on South Padre Island found significant beach erosion during the high tide cycle during the evening of the 20th, a result of continuing strong landward push of high seas and swell. It was likely that additional minor erosion affected the northern coast of Willacy County into the high tide over September 21/22.

Storm Surge/Tide in COASTAL KENEDY COUNTY, TEXAS
From 21-SEP-20 00:00:00 to 23-SEP-20 17:00:00 (CST-6)
Crop damage: 0.00K
Reported by: C-MAN Station

A tide gage at Baffin Bay, just north of the Kenedy/Kleberg County line, peaked at 2.34 feet above Mean Sea Level (MSL) around 8 PM CST September 21, and continued above 2 feet above MSL through 5 PM CST on the 23rd. Though tide levels inside Laguna Madre remained high through the 23rd, the lack of landward push of water from Beta that day as the cyclone had already made landfall on the 22nd along the central Texas coast, well north of Port Mansfield, suggested that the push may have ended earlier. However, since northern Kenedy County was much closer to the outswell from slow-moving Beta for several days, it's possible that additional run-up to or just into the dunes occurred for two or more day period.